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Our objective was to determine the effects of temperature and protein concentration on viscosity increase and gelation of liquid micellar casein concentrate (MCC) at protein concentrations from 6 to 20% during refrigerated storage. Skim milk (~350 kg) was pasteurized (72°C for 16 s) and filtered through a ceramic microfiltration system to make MCC and replicated 3 times. The liquid MCC was immediately concentrated via a plate ultrafiltration system to 18% protein (wt/wt). The MCC was then diluted to various protein concentrations (6–18%, wt/wt). The highest protein concentrations of MCC formed gels almost immediately on cooling to 4°C, whereas lower concentrations of MCC were viscous liquids. Apparent viscosity (AV) determination using a rotational viscometer, gel strength using a compression test, and protein analysis of supernatants from ultracentrifugation by the Kjeldahl method were performed. The AV data were collected from MCC (6.54, 8.75, 10.66, and 13.21% protein) at 4, 20, and 37°C, and compression force test data were collected for MCC (15.6, 17.9, and 20.3% protein) over a period of 2-wk storage at 4°C. The maximum compressive load was compared at each time point to determine the changes in gel strength over time. Supernatants from MCC of 6.96 and 11.61% protein were collected after ultracentrifugation (100,605 × g for 2 h at 4, 20, and 37°C) and the nitrogen distributions (total, noncasein, casein, and nonprotein nitrogen) were determined. The protein and casein as a percent of true protein concentration in the liquid phase around casein micelles in MCC increased with increasing total MCC protein concentration and with decreasing temperature. Casein as a percent of true protein at 4°C in the liquid phase around casein micelles increased from about 16% for skim milk to about 78% for an MCC containing 11.6% protein. This increase was larger than expected, and this may promote increased viscosity. The AV of MCC solutions in the range of 6 to 13% casein increased with increasing casein concentration and decreasing temperature. We observed a temperature by protein concentration interaction, with AV increasing more rapidly with decreasing temperature at high protein concentration. The increase in AV with decreasing temperature may be due to the increase in protein concentration in the aqueous phase around the casein micelles. The MCC containing about 16 and 18% casein gelled upon cooling to form a gel that was likely a particle jamming gel. These gels increased in strength over 10 d of storage at 4°C, likely due either to the migration of casein (CN) out of the micelles and interaction of the nonmicellar CN to form a network that further strengthened the random loose jamming gel structure or to a gradual increase in voluminosity of the casein micelles during storage at 4°C.

The oil and carbohydrates contained in the Moringa oleifera seeds (MO) are two parameters that inhibit its coagulant potential. Oil extraction and protein purification are therefore necessary to im...

The spectrophotometric method for measuring protein content can be used to evaluate the degree of proteolysis in cheeses. At a wavelength of 280 nm, tryptophan and tyrosine are absorbed, a high amount of them is found in casein, the main protein of cheese mass. It was found that the value of the absorbance coefficient of the solution of proteins extracted from flavoring additives with cheese flavor (FA) and cheeses depends on the degree of proteolysis of proteins in the cheese mass and differs in FA and different types of cheeses. The highest absorbance coefficient is observed in the FA samples A1%1cm = 10.30, in which from 65 to 81% of the protein is converted into a soluble state. In cheeses, the degree of proteolysis is from 23 to 33%, and the absorbance coefficient of solution is from 1.1 to 2.4 (with the exception of Cheddar cheese), which indicates an incomplete transition of amino acids absorbing radiation at 280 nm into the extract released from cheeses. Using the spectrophotometric method, the results of measuring the content of soluble protein in cheeses and FA, strictly correlating with the results achieved by the Kjeldahl method (R2 > 0.81), can be obtained. To get reliable results of evaluating the content of water-soluble protein in cheeses, it is necessary to carry out measurements on a sample of cheeses belonging to the same species group, having the same specificity of proteolysis and slightly different absorbance coefficient between samples within the instance.

espanolEl objetivo de este estudio fue evaluar el proceso de diafiltracion (DF) para la obtencion de un concentrado de proteina a base de lactosuero dulce. Para la evaluacion del proceso, se uso un proceso de diafiltracion en modo de ultrafiltracion considerando dos parametros de operacion: relacion volumetrica (RV) y numero de ciclos (NC). Se utilizo un sistema de separacion por membranas bajo el modulo de operacion de ultrafiltracion (UF) del tipo espiral polietersulfona con un tamano de corte de 10 kDa. Durante las evaluaciones fueron determinadas las siguientes variables: minerales por medio de la tecnica de espectrometria ICP (Calcio, Sodio, Potasio, Magnesio, Fosforo), contenido de Lactosa determinado mediante HPLC y contenido de Proteina por medio del metodo de Kjeldahl. Los resultados mostraron la efectividad del proceso con respecto a la eliminacion de Lactosa alcanzando valores superiores al 90% e incrementos en proteinas del 75% EnglishThe aim of this work was to study the diafiltration (DF) process to obtain a protein concentrate using sweet whey. For the evaluation of the process, ultrafiltration (UF) in diafiltration mode was used and two operating parameters were evaluated: volumetric ratio (RV) and number of diavolumens (NC). It was performed by an ultrafiltration membrane using a spiral wound polyether sulfone membrane with an MWCO of 10 kDa and both the influences of the added amount of diavolume and of the frequency of diavolumes were studied and the following variables were quantified: mineral content by ICP spectrometry techniques (Calcium, Sodium, Potassium, Magnesium, Phosphorus), content of Lactose determined by HPLC and Protein content by Kjeldahl method. The results showed the effectiveness of the process regarding to the elimination of the lactose reaching values of more than 90% and obtaining a percentage of protein close to 75%

Malt soluble protein (SP) can be determined by different analytical procedures such as Kjeldahl, combustion, or spectrophotometry. From a practical standpoint, the spectrophotometric method is the ...

Background. Oat (Avena sativa L.) is one of the most important sources of protein, oil, starch and dietary fibers, in particular β-glucans. Dietary fiber serves as a source of nutrition for the intestinal microflora and significantly affects not only its composition, but also the normal functioning of the intestine as a whole. In connection with the increased interest in β-glucans as a food component and dietary supplement, there is a need in a convenient and inexpensive method for determination of β-glucans content in grain. The article provides an overview of the existing methods for the isolation and determination of soluble β-glucans in cereals: enzymatic, alkaline, alkaline-enzymatic, colorimetric; their advantages and disadvantages are noted. The main disadvantages of some methods are the complexity and duration of execution, significant cost of the required reagents, and the inability to determine the exact content of β-glucans due to their insufficient purification from various impurities.Results. This study used the example of naked and covered oat cultivars to demonstrate applicability of the gravimetric method that we developed by modifying the alkaline method. Whole grain oat flour was pretreated with a 50% ethanol solution to inactivate β-glucanase and remove free sugars, some lipids, proteins, and other substances. β-glucans were released from the aleurone layer and the endosperm with a 5% sodium hydroxide solution, and finally extracted with a 70% ethanol solution. Β-glucans floated to the surface in the form of a bunch of fibers, which was then dried at a temperature about 100-102°C to constant weight and weighed. The content of β-glucans was calculated from the dry weight (%). The isolated β-glucans were checked for the presence of accompanying substances: the content of nitrogenous substances was determined by the Kjeldahl method, and the presence of starch was determined by a qualitative reaction with Lugolʼs reagent.Conclusions. The content of β-glucans in the grain of the studied samples ranged from 3.12±0.18 up to 4.65±0.17% of the dry weight. As a result of the study, the optimal conditions of β-glucans isolation were selected: the extraction mixtures ratios, as well as the modes of centrifugation, sedimentation and drying were established. It has been shown that this method makes it possible to isolate β-glucans with a minimum impurity of nitrogenous substances (0.07-0.12%) and no traces of starch. One of the advantages of the described method is its availability for mass analysis when studying a collection of grain crops.

There is an ever-expanding number of high protein dietary supplements marketed as beneficial to athletes, body builders, infant formulas, elder care, and animal feed. Consumers will pay more for products with high protein per serving data on their nutritional labels, making the accurate reporting of protein content critical to customer confidence. The Kjeldahl Method (KM) is the industry standard to quantitate dairy proteins, but the result is based on nitrogen content, which is an approximation of nitrogen attributable to protein in milk. Optical spectroscopy is commonly used for quality control measurements and has been identified as having the potential to complement the KM as a more nuanced testing measure of dairy protein. Infrared (IR) spectroscopy offers advantages over the KM in that IR provides an accurate representation of protein content in dairy products, and the results can be achieved very quickly. Protein analysis by IR has been used to study protein degradation in aged cheeses, and milk whey powder adulteration in whey protein concentrate supplements. The hypothesis of this thesis is that if mid-infrared (MIR) spectroscopy can be used to characterize individual whey proteins, then MIR should be applicable to qualitative analysis of protein powders and quality control monitoring of protein powder products for adulteration by inexpensive protein or amino acids. Protein powder analysis by KM revealed that the calculated total percent protein of the five protein powders tested was lower than the value stated on the product label, the percent variation between label protein content and that of the KM ranged from 2.9% to 9.5%. MIR spectroscopy spectra of four whey protein standards and four other protein standards provided qualitative characterization of each protein by amide I and amide II peak absorbance wavenumber. Product tampering by third-party manufacturers is an issue, due to the lack of United States Food and Drug Administration regulation of nutraceutical products, permitting formulators to add low-cost nitrogen-containing components to artificially inflate the KM approximated protein content of the products. Protein powders have been found to be doped with the amino acids glycine, leucine, and glutamic acid and inexpensive proteins, like bovine serum albumin. Controlled doping experiments were conducted with each of the above listed adulterants to assess the effectiveness of MIR spectroscopy to rapidly detect product tampering. Protein doping experiments revealed that as BSA amounts were increased, the amide I/II peak shape changed from the broad protein powder peaks to the narrower BSA peaks. Amino acid doping experiments revealed that the limit of detection for MIR spectroscopy, for the three amino acids used in this study, is 25%. MIR spectroscopy results may offer product quality assurance that is complementary to dairy protein measurement by the KM.

A low-cost and reliable analytical method based on the combination of a newly designed sticker-plastic sheet platform, digital image-based colorimetry and down scaled Kjeldahl digestion is proposed for the determination of protein content in food samples. The yellowish-brown colloidal products, obtained from the reaction between the ammonium–nitrogen after digestion and the working Nessler's reagent on the miniaturized sticker-plastic sheet platform, were captured for imaging with a smartphone camera. The operational parameters and reaction conditions were optimized. A down scaled Kjeldahl digestion procedure was performed using the newly designed digestion block. The parameters influencing the digestion efficiency, including the mass of the sample, volume of acid, mass of the catalyst and digestion time, were evaluated. Under the selected conditions, a linear calibration in the range of 5–60 mg L−1 ammonium–nitrogen was obtained with limits of detection and quantification of 2.8 and 7.6 mg L−1, respectively. The repeatability and reproducibility were 6.7% and 8.8%, respectively. The accuracy of the proposed method was evaluated by applying the developed procedure for milk powder and feeding stuff reference materials and comparing it with the conventional Kjeldahl method. The proposed method was successfully applied for the determination of protein contents in soy foods and protein-based foods. The results agreed well with those obtained from the conventional Kjeldahl method.

Improvements in the membrane separation of whey and subsequent spray drying for the recovery of Whey Protein Concentrate (WPC) have been investigated in the present work. Initially, ultrasonic pretreatment of whey was performed to reduce the microbial contamination and possibly improve the membrane separation based on inducing changes in the whey proteins. Studies involving the effect of important parameters in the membrane operation such as transmembrane pressure (TMP), type of membrane and molecular weight cutoff (MWCO) on permeate flux established that 10 kDa hydrosart membrane gives maximum permeate flux with minimum fouling at an optimum TMP of 1.2 bar. Studies with ultrasound assisted ultrafiltration established that the fouling was reduced with ultrasound also giving higher permeate flux. Effect of spray drying parameters such as air pressure, aspirator rate (rpm), feed flow rate and dilution on the WPC yield, analysed using SDS-PAGE and Kjeldahl method, has also been investigated. Additionally, the use of ultrasonic nozzle in the spray drying was investigated and the results were compared with pneumatic nozzle. Overall, it was clearly established that pretreatment, membrane characteristics, ultrafiltration operating parameters and spray drying parameters play an important role in deciding the WPC recovery from whey. Significant process intensification benefits were demonstrated to be obtained with the use of ultrasound both in membrane separation and spray drying.

This study aims to develop and validate rapid quantification technique for intact casein (IC) and total protein in cheddar cheese using SCiO™, a low-cost short-wave near-infrared spectrometer. SCiO™ was used to collect the spectral scans (from 740 nm to 1070 nm) of cheddar cheese (N = 49). Reference values of IC and total protein were quantified by the Kjeldahl method. The spectra acquired from the SCiO™ were preprocessed using standard normal variate and second derivation, and subsequently partial least squares regression (PLSR) based models were developed (ncal = 35). In addition, wavelength selection methods (backward elimination, multiple linear regression-forward selection, and inteval PLSR) were applied to further improve the model performances. Based on external validation (nval = 14), IC prediction resulted in a range of root mean square error of prediction (RMSEP) between 0.91 and 1.58 g/100 g cheese, and residual prediction deviation (RPD) between 1.2 and 2.1. For total protein prediction, the RMSEP ranged from 0.62 to 0.88 g/100 g cheese, while the RPD was found between 1.4 and 2.0. The prediction results indicated that SCiO™ can provide useful quantification tool for a rapid prediction of IC and total protein in cheddar cheese.

A urease extract prepared by decanting liquid from a suspension of finely ground Citrullus lanatus (watermelon) seeds was characterized and applied to dilute urine samples to demonstrate a low-cost...

Objective The study aims at evaluating mid-infrared human milk analyzer (HMA) accuracy and precision, in human milk (HM). Study design Röse-Gottlieb, high-performance anion exchange chromatography-pulsed amperometric detection (HPAEC-PAD), Kjeldahl and amino acid analysis (AA) were selected as references for total fat, lactose and total protein determination. Results No significant difference was observed in lactose content between HMA and HPAEC-PAD. Significant differences were observed in fat and protein content between HMA and reference methods. However, the difference in fat content was lower than 12%, and therefore within the variability declared by supplier. For protein determination, the BCA protein assay was selected. No significant differences were observed in total protein content measured by BCA assay, Kjeldahl and AA methods. Conclusions HMA was reliable for the quantification of total fat and lactose content, but not for total protein one. The latter was measured by BCA assay, which yielded comparable results to Kjeldahl and AA methods.

Ammonium ion of digested samples of food, soil, fertilizer and water was determined based on the reaction of the ammonium ion with formaldehyde, and then titrated with sodium hydroxide solution. The optimization of variables such as the amount of formaldehyde and EDTA concentration carried out through univariate analysis. Under optimized conditions, the method allowed ammonium determination with the achieved detection limit of 1.83mgL-1, a quantification limit of 6.11mgL-1 and precision of 6.0-0.5% for ammonium solutions of 0.400-3.773mgL-1 concentration, respectively. The procedure was validated using the Kjeldahl method. The method was successfully applied to determinate ammonium in samples of water, soil, fertilizer and oat. The proposed procedure resulted in a simple, fast and cost effective method to the determination of ammonium in routine analysis. O íon amônio de amostras digeridas de alimentos, solo, fertilizante e água foi determinado baseado na reação do íon amônio com formaldeído e, em seguida, titulado com solução de hidróxido de sódio. A otimização de variáveis como quantidade de formaldeído e concentração de EDTA foi realizada por meio de análise univariada. Em condições otimizadas, o método permitiu a determinação de amônio com o limite de detecção alcançado de 1,83 mg L-1, um limite de quantificação de 6,11 mg L-1 e precisão de 6,0 - 0,5% para soluções de amônio na concentração de 0,400 - 3,773 mg L-1, respectivamente. O procedimento foi validado pelo método Kjeldahl. O método foi aplicado com sucesso para determinar amônio em amostras de água, solo, fertilizante e aveia. O procedimento proposto resultou em um método simples, rápido e de baixo custo para a determinação de amônio em análises de rotina.

Our objectives were to determine if milk casein as a percentage of true protein (CN%TP) estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) is equivalent to CN%TP estimated by Kjeldahl, and to determine the proportion of casein (CN), casein proteolysis products (CNPP), and serum protein (SP) from milk true protein (TP) that goes into the Kjeldahl noncasein nitrogen (NCN) filtrate and the proportion that stays in the NCN precipitate using SDS-PAGE. Raw milk samples were collected from 16 mid-lactation Holstein cows twice a week for 2 wk. These milks were analyzed for Kjeldahl total nitrogen, nonprotein nitrogen, and NCN content in duplicate, and by SDS-PAGE. The CN%TP determined by Kjeldahl was compared with the CN%TP estimated by SDS-PAGE calculated in 2 ways: as a percentage of only intact caseins divided by TP and as a percentage of both intact caseins and CNPP divided by TP. Three milks varying in fat, lactose, TP, CN, and SP content were formulated. These milks were analyzed in duplicate for Kjeldahl total nitrogen, nonprotein nitrogen, and NCN content, and each of the NCN filtrate and NCN precipitate were analyzed in duplicate by SDS-PAGE for relative quantity (%) of CN, CNPP, and SP. We found that the estimate of CN%TP by Kjeldahl was higher than the estimate of CN%TP by SDS-PAGE that was calculated as only intact CN divided by the total of all protein bands. However, no difference was detected in the estimate of CN%TP by Kjeldahl compared with CN%TP by SDS-PAGE when CNPP were included as CN in the calculation of SDS-PAGE results. Based on SDS-PAGE results, we found that a majority (89%) of the CNPP from the milk (approximately 10.13 out of 11.41% TP) were retained in the Kjeldahl NCN precipitate. Thus, CN%TP measured by Kjeldahl underestimates the amount of proteolytic damage that has been done to CN in milk. It is important for the dairy industry to correctly and rapidly measure the extent of proteolytic damage to milk protein to correctly value milk from a product quality and yield point of view. A rapid and quantitative measure of proteolytic damage to milk protein is needed.

Our research objective was to measure percent removal of whey protein from separated sweet whey using 0.1-µm uniform transmembrane pressure ceramic microfiltration (MF) membranes in a sequential batch 3-stage, 3× process at 50°C. Cheddar cheese whey was centrifugally separated to remove fat at 72°C and pasteurized (72°C for 15 s), cooled to 4°C, and held overnight. Separated whey (375 kg) was heated to 50°C with a plate heat exchanger and microfiltered using a pilot-scale ceramic 0.1-µm uniform transmembrane pressure MF system in bleed-and-feed mode at 50°C in a sequential batch 3-stage (2 diafiltration stages) process to produce a 3× MF retentate and MF permeate. Feed, retentate, and permeate samples were analyzed for total nitrogen, noncasein nitrogen, and nonprotein nitrogen using the Kjeldahl method. Sodium dodecyl sulfate-PAGE analysis was also performed on the whey feeds, retentates, and permeates from each stage. A flux of 54 kg/m2 per hour was achieved with 0.1-µm ceramic uniform transmembrane pressure microfiltration membranes at 50°C. About 85% of the total nitrogen in the whey feed passed though the membrane into the permeate. No passage of lactoferrin from the sweet whey feed of the MF into the MF permeate was detected. There was some passage of IgG, bovine serum albumen, glycomacropeptide, and casein proteolysis products into the permeate. β-Lactoglobulin was in higher concentration in the retentate than the permeate, indicating that it was partially blocked from passage through the ceramic MF membrane.

1-phenyl(phenylimino)methyl)pyrrolidine-2,5-dione (FFMP) is a derivative of a well-studied class of organic compounds, pyrrolidine-2,5-diones, which have a wide spectrum of biological activity. Investigation in vivo in laboratory mice showed that FFMP, being an almost non-toxic compound (according to K. K. Sidorov), exhibits a pronounced analgesic activity, which is 1,6 times higher than the reference drug (metamizole sodium), acting in pain caused by chemical stimuli - algogens (model of visceral pain). This paper presents the results of attestation of the primary standard sample FFMP by the “mass balance” method. The structure of the compound was confirmed by X-ray structural analysis (XRD), mass spectrometry, nuclear magnetic resonance (NMR) spectrometry and infrared spectrometry (IR). The content of related organic impurities was determined by high performance liquid chromatography (HPLC). The content of volatile substances and inorganic impurities has been determined. The “mass balance” method was used to calculate the content of the main substance in the FFMP substance. The calculated value has been proven to be equivalent to the quantification value obtained by Kjeldahl titration. Using a certified primary standard sample, a method for the quantitative determination of the main substance by HPLC was developed and validated. Chromatographic separation was achieved in the acetonitrile / 0,15% (v/v) aqueous formic acid solution (pH 2,5) in a gradient mode on a Tosoh ODS column (4,6 × 250 mm, 5 μm) with a flow rate of 1,0 mL/min in 35 min. The signal was recorded using a multiwave UV detector at a wavelength of 257 nm.

The physicochemical properties of the novel original anxiolytic GML-1 drug substance were studied, analytical techniques for it were developed, and its main pharmacopoeial quality parameters were determined using IR spectroscopy, UV spectrophotometry, HPLC, and the Kjeldahl method.

Laboratory exercises focused on protein quantification are frequently conducted in traditional undergraduate biochemistry laboratory curriculum. The laboratory course described here is designed to provide students with experience in measurement of protein content in milk powder by moving reaction boundary titration (MRBT), a new rapid technique for total protein content determination in milk. In addition, this approach is weakly influenced by nonprotein nitrogen reagents such as melamine and urea. The course was done as three weekly laboratory exercises. First, students established a standard curve for milk protein concentration by MRBT method. Then, students investigated the influence of nonprotein nitrogen reagents on MRBT method. Finally, students made a comparison among three different protein quantification methods (MRBT, Biuret, and Kjeldahl method). From the experiments, students grasped the concept and advantages of MRBT and deepened the understanding of protein quantification. This course offer students the opportunity to be exposed to an advanced technique, which may have practical significance to their future study and work in the life science field. © 2018 International Union of Biochemistry and Molecular Biology, 46(6):644-651, 2018.

Ammonium and diphenhydramine are active ingredients commonly found in the same pharmaceutical preparations. We report, for the first time, a sub-minute method for the simultaneous determination of ammonium and diphenhydramine. The method is based on capillary electrophoresis with capacitively coupled contactless conductivity detection. Both analytes can be quantified in a single run (∼80 injections/h) using 30 mmol/L 2-(N-morpholino)ethanesulfonic acid and 15 mmol/L lithium hydroxide (pH 6.0) as background electrolyte. The separation by capillary electrophoresis was achieved on a fused-silica capillary (50 cm total length, 10 cm effective length, and 50 μm inside diameter). The limits of detection were 0.04 and 0.02 mmol/L for ammonium and diphenhydramine, respectively. The proposed method also provided adequate recovery values for spiked samples (100-106 and 97-104% for ammonium and diphenhydramine, respectively). The results obtained with the new capillary electrophoresis method were compared with those of the high-performance liquid chromatography method for diphenhydramine and the Kjeldahl method for ammonium and no statistically significant differences were found (95% confidence level).

Objetivou-se avaliar os efeitos das concentrações de hidróxido de sódio na etapa de destilação sobre os teores de nitrogênio (N) total obtidos pelo método de Kjeldahl em diferentes materiais. Foram utilizadas oito amostras de diferentes materiais, sendo quatro amostras com baixo teor de N (cana-de-açúcar in natura, fezes bovinas, milho grão e silagem de milho) e quatro amostras com alto teor de N (carcaça ovina, caseína, farelo de girassol e farelo de soja). Adicionalmente, foram avaliadas dois padrões com conteúdo conhecido de N (HCl-Lisina e sulfato de amônio). O período experimental foi de nove dias, em que cada grupo de amostras (padrões e amostras de baixo e alto teor de N) foi analisado durante três dias consecutivos (baterias de análise). Avaliaram se quatro concentrações de hidróxido de sódio na etapa de destilação: 300, 400, 500 e 600 g/L. Os padrões foram avaliados separadamente em termos de recuperação de N em modelo incluindo o efeito xo de concentração de hidróxido de sódio e o efeito aleatório de bateria de análise. As amostras de alto e baixo teor de N foram avaliadas separadamente em modelo incluindo o efeito xo de concentração de hidróxido de sódio e os efeitos aleatórios de bateria de análise, amostras e interação amostra × concentração de hidróxido de sódio. Vericou-se recuperação completa de N para os padrões (P>0,01). Não houve efeito de amostra, bem como interação amostra e concentração de hidróxido de sódio sobre a concentração de N nos diferentes materiais (P>0,01). Não foram vericados efeitos das concentrações de hidróxido de sódio sobre os teores de N dos materiais de alto e baixo nitrogênio (P>0,01). A variação na concentração de hidróxido de sódio não afetou a repetibilidade dos resultados. Conclui-se que concentrações de hidróxido de sódio de 300 a 600 g/L na solução empregada na etapa de destilação do método de Kjeldahl propiciam recuperação completa do N com padrão de precisão similar. Assim, considerando-se aspectos não técnicos, recomenda-se a utilização de solução com concentração de 300 g/L devido ao menor custo com reagentes.

The objective of our work was to develop and evaluate the performance of a rapid method for measuring fat, protein, moisture, and salt content of Cheddar cheese using a combination mid-infrared (MIR) transmittance analysis and an in-line conductivity sensor in an MIR milk analyzer. Cheddar cheese was blended with a dissolving solution containing pentasodium triphosphate and disodium metasilicate to achieve a uniform, particle-free dispersion of cheese, which had a fat and protein content similar to milk and could be analyzed using a MIR transmittance milk analyzer. Annatto-colored Cheddar cheese samples (34) from one cheese factory were analyzed using reference chemistry methods for fat (Mojonnier ether extraction), crude protein (Kjeldahl), moisture (oven-drying total solids), and salt (Volhard silver nitrate titration). The same 34 cheese samples were also dissolved using the cheese dissolver solution, and then run through the MIR and used for calibration. The reference testing for fat and crude protein was done on the cheese after dispersion in the dissolver solution. Validation was done using a total of 36 annatto-colored Cheddar cheese samples from 4 cheese factories. The 36 validation cheese samples were also analyzed using near-infrared spectroscopy for fat, moisture, and the coulometric method for salt in each factory where they were produced. The validation cheeses were also tested using the same chemical reference methods that were used for analysis of the calibration samples. Standard error of prediction (SEP) values for moisture and fat on the near-infrared spectroscopy were 0.30 and 0.45, respectively, whereas the MIR produced SEP values of 0.28 and 0.23 for moisture (mean 36.82%) and fat (mean 34.0%), respectively. The MIR also out-performed the coulometric method for salt determination with SEP values of 0.036 and 0.139 at a mean level of salt of 1.8%, respectively. The MIR had an SEP value of 0.19 for estimation at a mean level of 24.0% crude protein, which suggests that MIR could be an easy and effective way for cheese producers to measure protein to determine protein recovery in cheese making.

The goal of this study was to compare a Dye Binding Method with the standard Kjeldahl method in the context of protein determination in Ultra-Heat Treated (UHT) milk. Protein contents were determined in (25) samples of milk collected immediately post- ultra-heath treatment of milk and (25) samples collected after six-month storage at room temperature in Kjeldahl and Amido black methods. Samples digested using concentrated sulfuric acid at high temperatures and assayed using Automated Kjeldahl (Foss, Kjeltec™ 8200). Whereas, undigested samples were mixed with Amido Black a and density of color was measured against Amido black dilution series at wavelength of 620 nm. First stage: the average concentration of protein was (2.9256±0.01193 g/100 mL) versus (2.9396±0.01338 g/100 mL) using Kjeldahl versus Amido Black A respectively, with an average difference of (0,014). The concentrations ranged between (2.890-2.940 g/100 mL) and (2.910-2.960 g/100 mL) with a Coefficient of variation is (0.41%) and (0.46%) for Kjeldahl and Amido Black, respectively. (P) Value >0.0001. Therefore, there are no variances significantly different between two methods. Second stage: First stage: the average concentration of protein was (2.9224±0.03961 g/100 mL) versus (2.932±0.007071 g/100 mL) using Kjeldahl versus Amido Black A, respectively, with an average difference of (0.0096). The concentrations ranged between (2.770-3.000 g/100 mL) and (2.920- 2.940 g/100 mL) with a Coefficient of variation is (1.36%) and (0.24) for Kjeldahl and Amido Black respectively. (P) Value

Digesters fed on food waste (high nitrogen content) were operated successfully over an extended period using sidestream biogas stripping to control total ammonia nitrogen (TAN) below inhibitory concentrations. This is the first time biogas stripping has been used to achieve stable thermophilic operation with undiluted substrate of this type. Stripping columns operated batch-wise treated the equivalent of 1.7–4.1% of digester contents daily at pH >10 and 70 °C, with no detrimental effect on digestion. TKN removal was 54%, with potential to recover 3.5 kg N tonne −1 substrate. When stripping was stopped in one digester TAN increased, accompanied by rising propionic acid concentrations with progressive instability observed from 2.5 g N L −1 . Eventual failure as TAN approached 5 g N L −1 was due to rapid acetic acid accumulation, resulting in a fall in pH to below 6.5. The pattern of VFA accumulation indicated failure of both acetoclastic methanogenesis and acetate oxidation.

Glycomacropeptide (GMP) is a nutraceutical additive, which is released during cheese preparation. In this study, the protein content in a laboratory GMP preparation and two commercial GMP samples, which was estimated by the Bradford, biuret, Lowry and bicinchoninic acid (BCA) assays, were compared using the Kjeldahl method. There were apparent differences in the values of estimated proteins using the different methods. An absence of dose response in the Bradford method and a low dose response using the Lowry method indicated the unsuitability of both these methods. Absorbance in the biuret and BCA methods linearly increased with increasing GMP content. The BCA method was the most sensitive of these methods.

A flow injection conductometric (FIC) system for determination of total Kjeldahl nitrogen (TKN) was developed for estimating total protein content in food. A small scale Kjeldahl digestion was performed with a short digestion time of only 20min. The digested solution was injected into the FIC system, and TKN was converted to ammonia gas in an alkaline donor stream of the system. The gas diffused through a membrane and dissolved into an acceptor stream causing an increase in conductivity as detected by a detector and recorded as a peak. Under the optimum condition, a linear calibration graph in the range of 4.00-100.00mgL-1 was obtained with LOD of 0.05mgL-1. A good precision (0.04% RSD, n=11, 30.00mgNL-1) and high sample throughput of 72h-1 was achieved. The method was applied for determination of protein in some traditional northern Thai foods, revealing that they are good sources of proteins.

A modified biuret method suitable for protein determination of corn-based products was developed by introducing a combination of an alkaline reagent with sodium dodecyl sulfate (reagent A) and heat treatments. The method was tested on seven corn-based samples. The results showed mostly good agreement (P>0.05) as compared to the Kjeldahl values. The proposed method was found to enhance the accuracy of prediction on zein content using bovine serum albumin as standard. Reagent A and sample treatment were proved to effectively improve protein solubilization for the thermally-dried corn-based products, e.g. corn gluten meal. The absorbance was stable for at least 1-h. Moreover, the whole measurement of protein content only needs 15-20min more than the traditional biuret assay, and can be performed in batches. The findings suggest that the proposed method could be a timesaving alternative for routine protein analyses in corn processing factories.

Whole blood is a highly complex substance. Hemoglobin, the most abundant blood protein, can function as a flocculant; most of the other blood components exhibit poor flocculant activity. For the purpose of processing raw whole blood into a flocculant product, the practical value of hemoglobin purification is uncertain.; Results: This study compares the flocculant performance of whole blood to that of three different semi-purified hemoglobin preparations. The whole blood is processed to remove the plasma proteins, the solid cell components, or both. The flocculant performance of whole blood and each hemoglobin preparation is compared over wide ranges of flocculant dose and suspension pH. The clarified liquids are examined for increases in chemical oxygen demand and Kjeldahl nitrogen. Hemoglobin preparations that excluded plasma gave peak flocculation performance at approximately 30 mg solids per gram of suspended kaolin, and gave greatly reduced performance at higher doses; preparations that included plasma gave very similar peak performance, but also maintained relatively high performance at doses up to at least 200 mg g-1 .; Conclusion: It is shown that removal of the plasma and the cell solids does not improve the flocculant performance or lessen the residual pollutants in the treated water. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.; Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Kjeldahl and Dumas crude protein measurement methodologies do not distinguish between nitrogen native to milk and nitrogen in low molecular mass, nitrogen-rich adulterants. Measuring the non-protein nitrogen (NPN) content is one possible means of closing this loophole. Four methods were considered, with three selected for further research and validation: protein precipitation using trichloroacetic acid, protein precipitation using tannic acid, and molecular mass cut-off filtration. Kjeldahl assay was used on the supernatant or filtrate for all three methods. An NPN reference concentration range was established using 15 milk powder samples. This was followed by spiking experiments using seven low-molecular-weight, nitrogen-rich adulterants. Tannic acid precipitation and molecular mass cut-off filtration, both simple techniques available for routine use in food analysis laboratories, proved to be suitable for detecting the adulteration of milk powders with a variety of nitrogenous contaminants. NPN concentrations of ≥0.34% in milk powders are suspected to result from adulteration.

The study was carried out to gain insight into the effect of pretreatment on enzymatic hydrolysis of kitchen waste (KW) for xanthan fermentation. Herein, various pretreatments were applied and it was found that chemical pretreatment had positive effect on the following enzymatic or overall hydrolysis process. The highest reducing sugar concentration was obtained as 51.87g/L from 2% HCl (90°C) pretreated sample, while the Kjeldahl nitrogen (KDN) concentration was 7.79g/L. Kinetic study showed that first order kinetic model was suitable to describe the enzymatic hydrolysis process. The obtained kitchen waste hydrolysate (KWH) was successfully applied for xanthan fermentation. Xanthan concentration reached 4.09-6.46g/L when KWH with 2% HCl (90°C) pretreatment was applied as medium. In comparison, a xanthan concentration of 3.25-5.57g/L was obtained from KWH without pretreatment. Therefore, pretreatment of KW using diluted acid is favorable for the overall hydrolysis process and effective for xanthan fermentation.

Proteins are plant cell wall components but they are not included in the definition of dietary fiber. Therefore, dietary fiber preparations have to be corrected for their residual protein contents. This is commonly done by calculating the residual protein concentrations from the nitrogen contents after Kjeldahl digestion. Here, three different methods to determine nitrogen in Kjeldahl digests were compared: conventional titration with hydrochloric acid after steam distillation, a colorimetric assay (24-well microplates and cuvettes), and the determination by using an ammonia electrode. All assays gave similar results but detection using the ammonia electrode was found to be the most time-efficient approach. Also, an amino-acid profiling method, which is not based on commercial kits and which is suitable for routine analysis of dietary fiber preparations, was established. For this purpose, an HPLC-FLD method following amino acid derivatization using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) was optimized for fiber samples. Although all commonly used dietary fiber preparation methods involve the application of proteases the amino acid profiles of fiber samples from different sources were shown to be quite diverse. Considering the amino acid composition of the residual protein in various dietary fiber preparations, residual protein is probably not only based on structural proteins.

The method described in the article aims at the quantification of both main storage proteins, globulins and albumins, in aqueous extract from rapeseed, as an alternative to the current reference methods, Kjeldahl and SDS-PAGE electrophoresis. The new method lies on the analytical separation of extracted compounds by Size-Exclusion High Performance Liquid Chromatography (SE-HPLC) (Biosep-SEC-s2000, 5 µm). The elution of rapeseed extracts with water/acetonitrile/trifluoroacetic acid (45/55/0.1% v/v) during 30 min yields two distinct peaks for the main proteins of rapeseed. Based on the protein extinction coefficients, a calibrationless methodology was developed for their quantification on the basis of the UV signal. The SE-HPLC method was successfully compared to references: Kjeldahl and SDS-PAGE densitometry for the determination of the proportion of each protein. Then, it was successfully applied on two other oleoproteagineous plants, linseed and sunflower.

International audience; The aim of this research was to develop a method for simultaneous quantification of proteins and main polyphenolic compounds extracted from oleaginous meal by aqueous media. Size exclusion chromatography with a Biosep column (exclusion range from 1 to 300 kDa) and acetonitrile/water/formic acid (10:89.9:0.1 v/v) eluent at 0.6 mL min−1 yielded the most efficient separation of sunflower proteins and chlorogenic acid monoisomers (3-caffeoylquinic acid, 5-caffeoylquinic acid, and 4-caffeoylquinic acid). After a study of the stability of the extract components, the incorporation of a stabilization buffer (0.5 mol L−1 tris(hydroxymethyl)aminomethane-hydrochloric acid/1.0 mol L−1 sodium chloride at pH 7) was proposed to avoid polyphenol-protein interactions and/or isomeric transformation. The use of 214 nm as the wavelength for protein quantification was also included to minimize the effect of interference from polyphenol-protein interactions on the quantification. Under the used experimental conditions, the protein and chlorogenic acid monoisomer signals remained stable during 300 min at 20 °C (95–125% of the starting value). The developed method was validated and parameters such as specificity, sensitivity, precision, and accuracy were determined. The results from size exclusion chromatography correlated well with the results of protein determination by the reference Kjeldahl method. The proposed method was successfully applied for rapeseed extract analysis making simultaneous quantification of proteins and major rapeseed polyphenols (sinapine and sinapic acid) possible.

The properties of activated sludge are very important in a membrane bioreactor (MBR) in terms of membrane fouling. The most important parameters affecting the membrane fouling can be listed as mixed liquor suspended solid (MLSS) concentration, soluble microbial products (SMPs), extracellular polymeric substances (EPSs), floc size, aeration and viscosity of both supernatant and activated sludge. The COD/TKN ratio also affects the physical properties of sludge in MBR system. This study aimed to investigate the effect of chemical oxygen demand-to-total Kjeldahl nitrogen (COD/TKN) ratio of feed wastewater treated in an MBR on biological components of activated sludge. The activated sludge characteristics were determined by quantitative analyses such as MLSS, EPS, SMP, floc size distribution, zeta potential, relative hydrophobicity and capillary suction time in a submerged MBR treating simulated wastewater having different COD/TKN ratios (16, 56 and 107). The COD and TKN removal efficiencies were found to be almost equal in the sMBRs having different COD/TKN ratios. However, it was seen that the EPS content and SMP concentration in the supernatant increased with increasing COD/TKN ratio. The results indicated that the COD/TKN ratio of feed should be considered as an effective parameter on activated sludge properties in sMBR systems.

The work assessed the use of shear viscosity at 0.1 s−1 ( η [ 0.1 s − 1 ] ) as a parameter to detect changes in the conditioning and dewatering of digestates. Total and soluble fractions of organic matter of digestate samples before and after storage were also assessed in regards to their conditioning and dewatering performance. Digestate from a conventional mesophilic anaerobic digestion (CMAD) and advanced anaerobic digestion (AAD) plants were used. Linear regression and correlation analysis of 29 different parameters showed that soluble and total fractions of organic matter (Norg, Sc, Sp, Tp, TKN/COD, tCOD and sCOD) during plant operation and storage conditions correlated (r between 0.80 and 0.99) with the variation in polymer dose, floc strength and CST of conditioned digestate samples. The variations occurred within the content of soluble and total fractions of organic matter, and showed to correlate with both conditioning requirements and the variation in η [ 0.1 s − 1 ] . The work concluded that η [ 0.1 s − 1 ] measurements of unconditioned digestate samples have the potential to be used as a parameter to monitor conditioning requirements during digestate storage or during process changes. It was found important to analyse soluble and total fractions of organic matter in order to understand the changes in η [ 0.1 s − 1 ] within specific process conditions.

Precise measurement of cadaver decomposition rate is the basis to accurate post-mortem interval (PMI) estimation. There are many approaches explored in recent years, however, it is still unsolved completely. Total volatile basic nitrogen (TVB-N), which is an important index to predict meat freshness and shelf life in food science, could serve as an indicator for measuring PMI associated decomposition rate of cadavers. The aim of this work was to establish a practical method to determine TVB-N in cadaver soft tissues (mainly skeletal muscle) for measuring decomposition rate. Determination of TVB-N in the simulation and animal experiments was conducted by steam distillation and conductometric titration using Kjeldahl distillation unit and conductivity meter. In simulation, standard concentrations of ammonium were used as TVB analogies, TVB-N contents were determined and the recovery rates of nitrogen were calculated. In animal experiment, TVB-N in skeletal muscle of forty-two rats was determined at different PMIs for 312 h at 24 °C ± 1 °C. The relationship between PMI and TVB-N was investigated also. The method showed high precision with 99%–100% recovery rates. TVB-N in skeletal muscle changed significantly with PMI especially after 24 h, and the data fit well to y = 3.35 E −5 x 3 -2.17 E −2 x 2 +6.13x-85.82 (adj. R 2 = 0.985). EC i (initial electrical conductivity in the samples just before titration) had positive linear relationship to final measured TVB-N values, y = 1.98x+16.16 (adj. R 2 = 0.985). The overall results demonstrated that the method is accurate, rapid and flexible, which could be expected as a basic technique for measuring decomposition rate in later PMI-estimation researches. Further studies are needed to validate our findings.

The aim of the work was compared of two different methods (the visual method and the nephelo turbidimetry method) for determination of rennet coagulation time. It was observed the effect of heat treatment of milk; types of rennet and addition of different amount of CaCl2 into the pasteurized milk. It was used two different chymosin rennet. For the visual method was milk sample (100 mL) equilibrated at 35 °C, 1 mL of rennet was added into milk and was measured the time required for the first visible flakes (visual method). For the determination rennet coagulation time by nephelo-turbidimetry was removed part of milk with rennet and placed into nephelo-turbidimetry. Milk had a titratable acidity in the range from 6.5 to 7.0 °SH, average pH of milk was 6.68. Dry matter content was in range from 12.351 to 13.142%. The average content of protein by Kjeldahl was 3.14%, fat by Gerber 4.34%, lactose by polarimetry 4.68% and calcium content 1.1%. The pasteurized milk had the worst rennet coagulation time about 32 s compared to the raw milk. The difference coagulation time between milk with addition of 20 µL CaCl2 and 40 µL CaCl2 was in range 21 s to 26 s by visual method. The difference coagulation time between milk with addition of 20 µL CaCl2 and 40 µL CaCl2 was 15 s by nephelo-turbidimetry method. There occurred statistically non-significant differences in most of the measurements, comparingthe visual and the nephelo-turbidimetric method. The heat treatment, addition of CaCl2 and using of different rennet had an influence on the curd category. It was obtained, that using nephelo-turbidimetry shown objective results for measuring the rennet coagulation time contrary the subjective visual method. Further, the results obtained by nephelo-turbidimetry are accurate and determined with the lower variation.

We report development and validation of a simple, rapid, and accurate method for the quantitation of protein nitrogen, which combines Kjeldahl digestion and ion chromatography with suppressed conductivity detection and requires nanomolar amount of nitrogen in samples (≥10 μg protein). The mechanism of suppressed conductivity detection does not permit analysis of samples containing copper (present in Kjeldahl digestion solution) and aluminum (present in many vaccines as adjuvants) due to precipitation of their hydroxides within the suppressor. We overcame this problem by including 10 μM oxalic acid in Kjeldahl digests and in the eluent (30 mM methanesulfonic acid). The chromatography is performed using an IonPac CS-16 cation exchange column by isocratic elution. The method reduces the digestion time to less than 1 h and eliminates the distillation and titration steps of the Kjeldahl method, thereby reducing the analysis time significantly and improving precision and accuracy. To determine protein nitrogen in samples containing non-protein nitrogen, proteins are precipitated by a mixture of deoxycholate and trichloroacetic acid and the precipitates are analyzed after dissolving in KOH. The method is particularly useful for biological samples that are limited and can also be applied to food, environmental, and other materials.

This study investigated the performance of inclined tube anoxic/aerobic membrane bioreactor (itMBR) treating concentrated municipal solid waste leachate over 550 d at organic loading rates of 4.2–31.8 kg BOD/m3 d. At optimum loading of 18 kg BOD/m3 d, the itMBR could achieve high removals of 97% for biochemical oxygen demand, 94% for chemical oxygen demand, and 95% for total Kjeldahl nitrogen. Complete elimination of protein-like substances and partial removal of fulvic and humic acid-like substances were achieved. Major membrane foulants were found to be gel layers containing protein-like and polysaccharide-like substances and Ca-based inorganic scaling. Membrane cleaning using sodium hypochlorite followed by citric acid was found effective for the restoration of transmembrane pressure (TMP) while periodical chemical enhanced back-flushing at every 7–10 d could limit TMP increase rate and sustain the operation in long term.

This investigation was designed to explore the effects of Zinc Oxide Nanoparticles (ZnO NP) on egg quality and the mechanism of decreasing of yolk lipids. Different concentration of ZnO NP and ZnSO4 were used to treat hens for 24 weeks. The body weight and egg laying frequency were recorded and analyzed. Albumen height, Haugh unit, and yolk color score were analyzed by an Egg Multi Tester. Breaking strength was determined by an Egg Force Reader. Egg shell thickness was measured using an Egg Shell Thickness Gouge. Shell color was detected by a spectrophotometer. Egg shape index was measured by Egg Form Coefficient Measuring Instrument. Albumen and yolk protein was determined by the Kjeldahl method. Amino acids were determined by an amino acids analyzer. Trace elements Zn, Fe, Cu, and P (mg/kg wet mass) were determined in digested solutions using Inductively Coupled Plasma-Optical Emission Spectrometry. TC and TG were measured using commercial analytical kits. Yolk triglyceride, total cholesterol, pancreatic lipase, and phospholipids were determined by appropriate kits. β-carotene was determined by spectrophotometry. Lipid metabolism was also investigated with liver, plasma, and ovary samples. ZnO NP did not change the body weight of hens during the treatment period. ZnO NP slowed down egg laying frequency at the beginning of egg laying period but not at later time. ZnO NP did not affect egg protein or water contents, slightly decreased egg physical parameters (12 to 30%) and trace elements (20 to 35%) after 24 weeks treatment. However, yolk lipids content were significantly decreased by ZnO NP (20 to 35%). The mechanism of Zinc oxide nanoparticles decreasing yolk lipids was that they decreased the synthesis of lipids and increased lipid digestion. These data suggested ZnO NP affected egg quality and specifically regulated lipids metabolism in hens through altering the function of hen's ovary and liver.

Efficiencies of SBR and granular activated carbon (GAC)-SBR systems with textile industrial wastewater (TIW) containing basic dyes (Basic Red 46 (BR46) and Basic Blue 41 (BB41)) at hydraulic retention times (HRTs) of 3.0, 5.0, and 7.5 d were investigated. The results showed that the basic dyes could be adsorbed onto bio-sludge but the adsorption yield depended on the molecular structure and weight of the basic dye. BR46 could be adsorbed onto the bio-sludge with higher yield than BB41. Also, the color adsorption yield of living bio-sludge was 22% higher than that of autoclaved bio-sludge (thermally treated bio-sludge). Moreover, the bio-sludge from a domestic wastewater treatment plant showed higher color adsorption yield than the bio-sludge from a textile wastewater treatment plant. The GAC-SBR system was more suitable than the SBR system to treat TIW. The highest color, COD, BOD5, total Kjeldahl nitrogen (TKN), and total nitrogen (TN) removal efficiencies of the GAC-SBR system with TIW at HRT of...

Considering the two collagen rich foods and extracted out the collagen protein from it by the method of acid soluble collagen (ASC). Collagen is naturally occurring fibrous protein which is important in maintaining the health and vitality of connective tissues. They work with elastin, another structural protein to maintain connective tissues elasticity. They may get benefit from the two amino acids lysine and proline and the presence of collagen promoting nutrient such as vitamin C. In the present study determination was done by ASC in which the sample was dissolved in 30 ml of 0.1N NaOH and filtration was done. After that the supernatant took as acid soluble followed by precipitation with 2.6M NaCl involving centrifugation at 38,400rpm for about 20 minutes and the residues were separated. At last, wet and dried separated residues were taken for protein determination by kjeldahl’s method. From this study it was concluded that the dry and wet percentage of protein is more than the total soy protein which means that the extracted protein was collagen.

Fluorescence spectroscopy in combination with multivariate statistical methods was employed as a tool for monitoring the manufacturing process of pertactin (PRN), one of the virulence factors of Bordetella pertussis utilized in whopping cough vaccines. Fluorophores such as amino acids and co-enzymes were detected throughout the process. The fluorescence data collected at different stages of the fermentation and purification process were treated employing principal component analysis (PCA). Through PCA, it was feasible to identify sources of variability in PRN production. Then, partial least square (PLS) was employed to correlate the fluorescence spectra obtained from pure PRN samples and the final protein content measured by a Kjeldahl test from these samples. In view that a statistically significant correlation was found between fluorescence and PRN levels, this approach could be further used as a method to predict the final protein content.

Royal jelly has become a high-value commercial product and the standardization of this product is required to guarantee its quality on the market. The objective of the research activity was to pursue the chemical composition of commercial samples of Royal Jelly in Romania in order to propose standardization for this product. The physico-chemical composition of commercial Royal Jelly samples was analysed by determining quality parameters like: carbohydrates, lipids, proteins, 10-hydroxy-2-decenoic acid (10-HDA) and mineral elements. Carbohydrates analysis showed values between 3.4 % and 5.87 % for fructose, 4.12 % and 7.05 % for glucose, while for sucrose the values ranged between 0.95 % and 2.56 % (determined by HPLC-RI). The lipids content ranged between 1.85 % and 6.32 % (determined by the Soxhlet method). The protein values extended from 13.10 % (RJ2) to 17.04 % (RJ10) (the total protein content was determined by the Kjeldahl method). The values for the major fatty acid in Royal Jelly, 10-HDA, ranged between 1.35 % (RJ8) and 2.03 % (RJ10) (determined by high-performance liquid chromatography). The concentration of minerals varied between 3188.70 mg/kg and 4023.39 mg/kg (the concentration of minerals was measured using flame atomic absorption spectrometry). Potassium, followed by magnesium, sodium and calcium, occurs in the highest concentrations. The commercial Royal Jelly samples analysed presented variable physico-chemical characteristics that correspond with the values given by international quality standard proposals for Royal Jelly.

The main hurdle for the estimation of the purity of 1,3,5-triamino-2,4,6- trinitrobenzene (TATB) is its insolubility in most of the known organic solvents. In the conventional method, TATB is digested with steam in a modified Kjeldahl digester and the ammonia evolved is estimated quantitatively. To do away with this cumbersome method, a simple, rapid HPLC technique using a reverse phase C-18 column has been established for quantitative determination of the purity of TATB. A sharp and symmetrical peak with a retention time of 2.92 min at 355 nm is obtained for pure TATB when the flow rate is 2.0 mL/min. The linearity of the detector response has been studied with sample concentrations ranging from 10 to 50 mg/L. The method addresses two important issues of sample preparation and the precision of measurement. Unlike the previously reported HPLC techniques which mainly aimed at the detection of TATB, the present work is a validated account of a quantitative estimation of purity. Regular production batch samples have been assayed by this method and the results are compared with those obtained from the conventional analysis. The HPLC method is convenient and reliable for quality control of the product at the plant level.

The impact of subcritical water processing (SWP), in a temperature range of 240-300 °C, on the formation of hydrolysates from bovine serum albumin (BSA) was investigated in this study. SDS-PAGE analysis of the samples treated at all temperatures did not reveal any bands. Yield, as evaluated by the Kjeldahl and Biuret methods, varied and decreased beyond 280 °C (P 0.05). The molecular mass of the hydrolysates was highly affected by temperature, with the formation of a new low molecular weight peak, as revealed by gel permeation chromatography. SWP at 280 °C caused the greatest release of free amino groups, as shown by the TNBS assay (P 0.05). Regardless of the type of amino acids, the maximum amount was obtained at 280 °C. At this temperature, the generation of alanine and glycine was relatively high. The optimization of processing parameters may enhance the production of valuable peptides without the need for additional catalysts.

This paper shows the effect of organic shock loads (OSLs) on the anaerobic digestion (AD) of synthetic swine wastewater using an expanded granular sludge bed (EGSB) reactor modified with zeolite. Two reactors (R1 and R2), each with an effective volume of 3.04 L, were operated for 180 days at a controlled temperature of 30 °C and hydraulic retention time of 12 h. In the case of R2, 120 g of zeolite was added. The reactors were operated with an up-flow velocity of 6 m/h. The evolution of pH, total Kjeldahl nitrogen, chemical oxygen demand (COD) and volatile fatty acids (VFAs) was monitored during the AD process with OSL and increases in the organic loading rate (OLR). In addition, the microbial composition and changes in the structure of the bacterial and archaeal communities were assessed. The principal results demonstrate that the presence of zeolite in an EGSB reactor provides a more stable process at higher OLRs and after applying OSL, based on both COD and VFA accumulation, which presented with significant differences compared to the control. Denaturing gradient gel electrophoresis band profiles indicated differences in the populations of Bacteria and Archaea between the R1 and R2 reactors, attributed to the presence of zeolite.

The long-term (90 days) impact of dosing FeCl3 on bioprocess performance and membrane performance in a pilot AnMBR fed with authentic sewage was evaluated. The addition of 26 mg/L of FeCl3 enhanced the performance of the AnMBR with respect to removal efficiencies of COD and BOD5, but did not have a significant influence on the removal efficiencies of TKN and TP and the methane yield. The membrane was operated at a constant flux of 17 LMH and its performance was significantly improved by dosing FeCl3. This was demonstrated by a reduction in the fouling that withstood scouring stresses to values lower than 5 kPa and negligible reversible fouling for the first 75 days. The superior membrane performance was consistent with the shift of particle size distribution to the particulate fraction and the reduced colloidal and soluble substances in the sludge, especially the soluble protein, carbohydrate, Ca and S. CLSM tests showed that the addition of FeCl3 resulted in a thicker foulant layer and the deposition of protein and carbohydrate on the membrane surface was significantly reduced. Therefore a more porous foulant layer was formed and this prevented the development of a strongly-attached cake layer and pore blocking. A recovery cleaning study indicated FeCl3 dosing enhanced the efficiency of the recovery cleaning protocol. The foulants formed with the Fe-dosed sludge had greater inorganic content, as 75% of the foulant resistance was removed by citric acid. The superior membrane performance during the operation combined with enhanced cleaning efficiency by FeCl3 dosing would significantly improve the sustainability of AnMBR in municipal wastewater treatment.