Search

The proximate, minerals, amino acid and fatty acid composition of wild, pond-, gher- and cage-cultured tilapia in Bangladesh were evaluated and varied significantly (p < 0.05). The major component of the tilapia was moisture (79.12%–81.36%), followed by protein (14.93%–16.03%), lipid (0.59%–2.35%), carbohydrate (1.23%–1.51%), fibre (0.47%–0.88%), ash (0.31%–0.53%); the energy value was between 97.62 and 126.73 kcal/100 g. Macro-nutrients and micro-nutrients were detected in following order: K > Na > Mg > Ca and Fe > Mn, respectively in all the tilapia and the ratio of Na/K was

A gas chromatographic method was developed for the quantitative determination of the monosaccharides of the soluble, insoluble fractions and the total non-starch polysaccharides (NSPs) content in foods with fat contents of less than 5%. Sample preparation involved enzymatic removal of starch and acid hydrolysis of the NSP to their constituent sugars. The alditol acetate derivatives were analysed on a wide bore capillary column with detection by flame ionization. The method was accurate, with recovery of spiked samples between 93.6% and 102.7% for intra-day analysis and between 93.2% and 104.7% for inter-day analysis. Repeatability was excellent; RSD values from 0.1 to 4.4% and 0.2 to 5.7% were observed from intra-day analysis and inter-day analysis, respectively. The peaks for all neutral sugars were sharp and separation was at baseline resolution with no interfering or co-eluting peaks.

This chapter presents some selected types of bioactive compounds from these sources, the way of incorporating them in foods and examples of testing their effects on human health. It deals with the techniques used to study the potential beneficial effects of bioactive phytochemicals for human health. Food is an essential factor for the survival of humans. Among foods that are characterised as functional foods, honey and other products originating from the beehives take a prominent place. Honey, propolis and royal jelly may be used as functional foods because they have high antioxidant potential. The recovery of anthocyanin after extraction depends primarily on the types and concentration of solvents, time, temperature and solvent to solid ratio. Plants have long been used as health foods and sources of medicinal properties. The anthocyanins in a product may present in much lower concentrations than expected because the anthocyanin itself is sensitive to various processing conditions.

Turmeric (Curcuma longa), belongs to Zingiberaceae family. The rhizomes contain bioactive compounds of the curcuminoids group (natural phenols). They are used in food and pharmaceutical industry. The aim of this research was to acquire dried turmeric with high total curcumin content. In this study, optimum turmeric drying conditions and new extraction techniques were explored. Fresh turmeric samples were subjected to constant vs changing drying air temperatures and pre-treatment (blanching). Changing drying air temperature and use of non-blanched turmeric slices resulted in the highest concentration of curcumin. Ultrasonic extraction instead of soxhlet extraction improved the extraction efficiency and decreased extraction time. Keywords: Turmeric, Curcumin; Drying; Blanching; Extraction

Brown kernels or internal discolouration (IDC) in various varieties of Macadamia nuts ( Macadamia integrifolia and Macadamia tetraphylla ) occurred through three different pathways: (i) an enzymatic browning reaction, (ii) Maillard reaction and (iii) infection by microorganisms. The phenolic compounds and polyphenol oxidase (PPO) activities of macadamias were analysed. Brown sections of the same kernel had higher levels of bound phenolics compared to the white sections, indicating the participation of phenolic compounds in the formation of brown kernel. The Maillard reaction was studied by determining the sugar amount using HPLC. The reducing sugars during drying reacted with kernel proteins causing the formation of brown pigments. Among the various varieties studied, ‘Daddow’ variety showed the least degree of hydrolysis. When kernel was infected with Penicillium aurantiogriseum , the kernel turns brown. The internal discoloration in macadamias is the first report that has been explored in our study. The findings of this study have potential to improve the existing postharvest techniques used in the Macadamia processing industry.

Summary Polyphenolic-rich fraction obtained from locally produced dry ginger powder in Brahmaputra valley, India, and commercially available dry ginger (Zingiber officinale) rhizome powder consisted of [6]-gingerol (41.9%), [6]-shogaol (24.3%), 1-dehydro-6-gingerdione (8.6%), [8]-gingerol (7.2%), [10]-gingerol (5.1%), [6]-paradol (5.9%) and [4]-gingerol (3.6%). Traces of methyl-[6]-gingerol and methyl-[8]-gingerol (both at 1.8%) were also detected. The fraction exhibited high antioxidant capacity [total phenolics (TP), ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC) and cellular antioxidant activity (CAA assay)], effectively inhibited isolated digestive enzymes (α-glucosidase, pancreatic lipase and angiotensin converting enzyme) and inhibited the proliferation of colon (HT29; IC50 of 1.06 ± 0.02 mg mL−1) and gastric (AGS IC50 of 1.29 ± 0.03 mg mL−1) adenocarcinoma cells, without affecting the proliferation of their nontransformed counterparts (IC50 > 2.0 mg mL−1). This case study demonstrates that locally produced and commercially available dry ginger powder from Brahmaputra valley, India, retains numerous food components that may enhance human health.

International audience; The effects of konjac glucomannan (KGM) on the gelatinization, retrogradation and complexation properties of potato and broad bean starches were investigated by differential scanning calorimetry and X ray diffraction. It was established that the addition of 1% KGM in starch suspensions causes a slight decrease in the amount of available water in the system. However, this seems sufficient to disrupt the gelatinization and the retrogradation of potato and broad bean starches. In addition, the ability of amylose to interact with carvacrol is strongly affected by the presence of KGM. A rheology study showed on one hand that addition of KGM to starch decreased the gel character of the system, irrespective of the presence of carvacrol. However, carvacrol induced a strong increase of the storage modulus of starch gel for the same KGM content.

In this study, new method was investigated using solid phase microextraction (SPME) for detection of insect infestation in stored wheat. The results show that volatile pheromones isolated from a number of common stored grain insects, can be used to indicate infestation. The amounts of pheromone released varied between species. Rhyzopertha dominica (F.) was the highest volatile pheromone producer among the species investigated, then it was followed by Tribolium castaneum (Herbst), Cryptolestes ferrugineus (Stephens) and Cryptolestes pusillus (Schonherr), respectively. This resulted in different sensitivity when SPME was used for detection. A single specimen of T. castaneum and R. dominica could be successfully detected in 1 kg of wheat, whereas more number of C. ferrugineus and C. pusillus beetles were required for detection in the same quantity of grain. Extraction period and temperature affected the sensitivity of the SPME method. Longer exposure time and higher temperature allowed more analytes to be collected. Consequently, extraction for 4 h at 50 °C appeared to be the optimum condition for extracting pheromones produced by the beetles covered by this study. The method was further adjusted to be more practical and this resulted in changing the sensitivity. Detection of a single R. dominica could still be successfully achieved, even though the time and the temperature were reduced, whereas for the remaining species, the minimum number of insects required had to be increased by about 40–60% in order to detect volatile pheromone in headspace. In conclusion, the SPME technique in detection of infestation is still required further development to be applied to the grain industry. Dynamic headspace may help improve the sensitivity of technique.

Davidson's plum (DP; Davidsonia pruriens, F. Muell, Cunoniaceae) and quandong (QD; Santalum acuminatum, A.D.C., Santalaceae) are two leading commercially grown native Australian fruits used in a variety of food products such as jam, chutney, sauces, wine or herbal teas. Within this study their inhibitory activities towards key enzymes relevant to metabolic syndrome: α-glucosidase, pancreatic lipase and angiotensin I-converting enzyme were evaluated and compared to these of reference samples: rabbit eye (REB, Vaccinium ashei J.M. Reade) and southern highbush (SHB, Vaccinium darrowii × Vaccinium corymbosum) blueberries. Polyphenolic-rich fraction obtained from DP comprised ellagic acid and ellagitannins accompanied by flavonoids: myricetin, quercetin, rutin, and anthocyanins. This fraction contained the highest level of total phenolics and exhibited superior antioxidant capacity (Ferric Reducing Antioxidant Power, FRAP and Oxygen Radical Absorbance Capacity, ORAC) to polyphenolic-rich fractions of QD, REB and SHB. DP closely followed REB and SHB in their inhibitory activities against isolated α-glucosidase (IC50 of 0.13; 0.097 and 0.091, respectively) and was the most efficient inhibitor of angiotensin converting-enzyme (ACE; 91.2% inhibition at extract concentration of 1 mg/mL). Polyphenolic-rich fraction of QD comprising hydroxycinnamic acids, quercetin and cyanidin 3-glucoside was the most effective inhibitor of pancreatic lipase (IC50: 0.60 mg/mL).

Ginger and turmeric, members of the Zingiberaceae family, are widely used for their pungent and aromatic flavour in foods and also for their medicinal properties. Both crops are often grown by smallholders in mountain areas on rich former forest soils with no need for fertilizers and pesticides, fulfilling de facto the conditions of organic agriculture. They are consumed fresh or dried. Drying is often performed without taking into account the content of bioactive compounds in the dried product. Various bioactive compounds have been identified in their rhizomes, and their content affects the price of the dried product. Hence, this study focused on the effects of drying treatments and blanching on the retention of bioactive compounds in the dried products. The bioactive compounds in ginger rhizome (Zingiber officinale Roscoe) are gingerols (particularly 6-gingerol). The drying treatments that were applied to fresh ginger included constant and also changing temperature conditions. Due to the short drying time, 60 °C was the optimal drying temperature to retain 6-gingerol. However, the changing temperature conditions significantly improved the retention of 6-gingerol. As for blanching, it had a significant negative effect on 6-gingerol retention. Turmeric (Curcuma longa) is known for its bright yellow colour and pharmacological properties due to curcumin, a phenolic compound. Drying was performed under constant conditions at 38 °C, 48 °C, 57 °C and 64 °C and a relative humidity of 20% and 40%. Drying at 57 °C with a lower relative humidity was the best drying treatment, yielding the highest amount of curcumin among non-blanched samples. Blanching for 15 min exhibited the highest curcumin yield while blanching for 5 min and 30 min did not have much effect. The findings of this study will benefit the industry in terms of improved quality control and cost reduction.

Macadamia nuts are well known for their unique flavor and taste. They contain a high level of monounsaturated fatty acids such as oleic acid, which is claimed to have an effect on reducing blood cholesterol. This study focuses on monitoring the changes in the physical and chemical qualities of macadamia nuts during drying, roasting, and storage. A combination of heat pump drying and tunnel drying was selected for this study to provide a comparison with convectional hot air drying. After completion of all drying treatments, the dried nuts were subjected to roasting at 125°C for 20 min and storage in ethylene vinyl alcohol copolymer (EVOH) bags at 4°C for 3 months. After each stage of processing, nut samples were taken to assess the quality in terms of fatty acids, moisture content, water activity, peroxide value, free fatty acids, color, and volatile compounds. The experimental results showed that drying treatments using heat pump combined with tunnel drying can reduce drying time significantly. It appears...

This paper describes the effects of spray drying temperature and wall materials on functional properties of kaffir lime oil microcapsules. The effects of spray drying were studied at inlet air temperatures at 160, 180, and 200°C. Two coating materials (konjac glucomannan and gum arabic) were employed in this study. The results indicate that kaffir lime oil had antibacterial activity against all tested pathogens and was able to inhibit Vibrio cholerae comparable to a standard antibiotic. The combination of konjac glucomannan and gum arabic (KGM+GA) can enhance the yield and retention of total oil in the microcapsules more than using konjac glucomannan alone as a wall material. Increasing inlet air temperature resulted in a decrease of antibacterial activity and amount of bioactive volatile compounds. Physical and chemical properties of the microcapsules did not differ significantly (p > 0.05) in terms of process yield, a w , moisture content, efficiency in retention of total, surface and inner oil, water s...

Anthocyanins were identified and quantified in various cultivars of blueberries grown in Australia. Those were Crunchie, Star and Sharpe (highbush, Vaccinium corymbosum L.) and Climax, Powderblue and Brightwell (rabbiteye, Vaccinium ashei). A method was developed involving liquid chromatography–mass spectrometry and UV–visible spectroscopy. The repeatability of injection was less than 2% relative standard deviation (RSD) while the repeatability of sample preparation was less than 10% RSD in most cases. The method was linear between 7% and 100% of the original concentration. The anthocyanin profile was similar in all cultivars but proportions of each compound were cultivar-dependent. Highbush had more early eluting peaks, i.e. more polar anthocyanins, than rabbiteye cultivars. Delphinidin, petunidin and malvidin were the major contributors to total anthocyanin content. Climax had the highest total anthocyanin content (13.7 ± 1.4 g cyanidin 3-glucoside equivalent kg−1 dry weight) and antioxidant activity (using 2,2-diphenyl-1-picrylhydrazyl as a free radical) of all tested cultivars. Rabbiteye had significantly higher total anthocyanin content than the highbush cultivars.

The purpose of this study was to develop and test a control system using supplementary heating for in-store drying of grain, to be used in major maize growing areas of Northeast China. In-store drying is using near-ambient air ventilation and the control system is aiming at maintaining the relative humidity of the drying air at a constant level. This can be achieved by increasing the temperature of the drying air by up to 5 °C using a small coal or biomass furnace. The control system is based on the results from previous studies and applies principles of the control theory. The system developed in this study includes a host PC and a distributed data acquisition and control system (DA&C). A drying simulation program, using drying equations for deep-bed drying and various quality models, has been used to investigate the effects of the control parameters and their possible interactions and to optimise the drying process. Several tests were conducted under different conditions to determine the performance of the control system in terms of response time and accuracy. Weather characteristics of key locations in Northeast China were analysed and found to be suitable for application of this control system. Pilot plant experiments and computer simulation results were compared in order to determinate control system performance. Economic aspects of the use of the control system were discussed in terms of fixed cost, labour cost and energy cost.

The physical states of water and its freezing behaviour in shelled corn during subzero drying were determined by using 2 H NMR and 1 H MRI techniques. In this context, the 2 H NMR spin–lattice relaxation times ( T 1 ) and spin–spin relaxation times ( T 2 ) of water in corn were measured. The relaxation times were found to decrease with decreasing temperature. The results revealed that there were two main water components in corn of >30% wb (wet basis) with long and short T 1 . Both components exhibited minima around −20 °C. In more dehydrated corn (18.6% wb) only a single water component, with short T 1 and T 2 was observed. 1 H MRI images revealed the location of water and its freezing behaviour in different areas.

The effects of high-temperature drying on Thai Jasmine rice were investigated. Paddy was first rewetted and then dried using a two-stage drying process, involving a fluidized bed at high temperature, followed by shade drying (ambient air drying). Three high drying temperatures: 100, 125, and 150°C were studied. Volatile compounds were extracted by distillation and extraction in a Likens and Nickerson apparatus, and analyzed by gas chromatography–mass spectrometry. A total of 94 volatile compounds were identified. These included 21 alcohols, 19 aldehydes, 14 ketones, 12 acids, 9 heterocyclic compounds, 8 hydrocarbons, 5 esters, and 6 miscellaneous compounds. 2-Acetyl-1-pyrroline, a major constituent of volatiles in fragrant rice was identified and tended to increase in concentration with increasing drying temperature. The three different drying temperatures used in the fluidized bed dryer were found to have an effect on the volatile components of Thai Jasmine rice. The increase in drying temperatu...

This study examined the effects of freezing, storage, and cabinet drying on the anthocyanin content and antioxidant activity of blueberries (Vaccinium corymbosum L). Fresh samples were stored for two weeks at $\5^\circ$ C while frozen samples were kept for up to three months at $-20^\circ$ C. There were two drying treatments, one including osmotic pretreatment followed by cabinet drying and the other involving only cabinet drying. Total anthocyanins found in fresh blueberries were $7.2 \pm 0.5$ mg/g dry matter, expressed as cyanidin 3-rutinoside equivalents. In comparison with fresh samples, total anthocyanins in untreated and pretreated dried blueberries were significantly reduced to $4.3 \pm 0.1$ mg/g solid content, 41% loss, and $3.7 \pm 0.2$ mg/g solid content, 49% loss, respectively. Osmotic treatment followed by a thermal treatment had a greater effect on anthocyanin loss than the thermal treatment alone. In contrast, the frozen samples did not show any significant decrease in anthocyanin level during three months of storage. Measurement of the antioxidant activity of anthocyanin extracts from blueberries showed there was no significant difference between fresh, dried, and frozen blueberries.

Ergosterol, the predominant sterol found in most fungi, is considered as an indicator of fungal invasion in grain. An extraction method based on solid phase extraction (SPE) has been developed for determination of ergosterol in unmilled rice, generally called paddy. The samples obtained by extraction through SPE have been analysed by HPLC. The method has been validated in experiments with paddy subjected to different drying treatments and recoveries above 85% have been obtained. SPE appeared to be simple, quick, reliable and consistent for ergosterol analysis. The ergosterol levels obtained in the paddy samples were found to be within the expected range and were comparable with those found using conventional methods. Copyright © 2004 Society of Chemical Industry

Heat pump dryers were studied as an alternative to freeze drying for dehydration of lactic acid bacteria for starter cultures. Factors investigated were bacterial growth phase, addition of dehydro-protectants, drying conditions, drying media and storage life of the dried bacteria. The main criterion for evaluation was the activity of the dried product. Results indicated that single dehydro-protectants were not able to give high activities, but suitable combinations were found giving results at least equal to freeze-drying. Nitrogen purging was found to give a significant improvement in activity.

The appropriate stage of maturity of Andrographis paniculata (AP) was selected based on the level of phytochemicals. Prior to drying, samples were blanched in boiling water. The Modified Halsey and Modified Henderson models offered the best fit of desorption isotherms for fresh and blanched AP, respectively. AP was dried in a tray dryer (TD) and heat pump-dehumidified dryer (HPD) at 40–60 °C; microwave dryer (MWD) at 270–720 W and freeze dryer (FD). Five mathematical models were fitted into the experimental data. The three-parameter model gave the best fit. The drying rate constant was related to the drying temperature using the Arrhenius model. Effective moisture diffusivity was increased with increase in drying temperature and microwave power. HPD and blanching increased antioxidant activity, total phenolics, andrographolide, and neoandrographolide by 1.45, 11.16, 6.31, and 23.57%, respectively. The blanching pretreatment followed by HPD should be considered for drying AP for its further utilization. Practical applications Andrographis paniculata (Burm.f.) Nees has been used in a traditional herbal medicine to treat the common cold, fever, and diarrhea. The active components of A. paniculata are very bitter diterpene lactones known as andrographolide and neoandrographolide found in the aerial parts but contained the maximum contents in leaf. The pretreatment followed by drying process may greatly influence the quality of A. paniculata leaves. Heat pump-dehumidified dryer (HPD) was adopted for dried A. paniculata in order to obtain dehydrated herb with high drying quality. The knowledge of drying kinetics was used to find the optimum point of the drying process for A. paniculata. The results of this study revealed that blanching followed by HPD could reduce drying time and increase phytochemical contents compared with commercial product and will be useful in the pharmaceutical products with good chemical properties.

Konjac glucomannan flour, which mainly consists of glucomannan, is an indigestible dietary fiber. Therefore, it has been broadly used as low-calorie food ingredient in various kinds of foods, beverages, and pharmaceutical products. In this study, the production of dried konjac noodles was evaluated by studying the effects of alkalinity using limewater versus calcium hydroxide and the gelling agent sodium alginate on textural properties of konjac noodles. Drying and rehydration conditions were studied to evaluate the optimum conditions for producing dried konjac noodles. By considering the springiness and cohesiveness of the konjac noodles, the results indicated that using 3% konjac glucomannan flour with limewater and an incubation time of 30 min were the most suitable conditions. In addition, hot air drying at 80 °C for 55 min and soaking in hot water for 9 min were the optimum drying and rehydration conditions.

Banana pseudostem is known to be beneficial to health, but so far is rarely used by the food industry. Pseudostems from two banana species (Musa balbisiana and Musa acuminata) were dried in a cabinet dryer. Four drying treatments were chosen for Musa balbisiana: 40C without (BP40) and with 3 min blanching at 70C (BP40B), 50C without (BP50) and with 3 min blanching at 70C (BP50B). BP50 resulted in lowest moisture content (4.4%), highest drying efficiency, ash (14.0%), total mineral content (6579.3 mg/100 g) and whitest colour. There was no significant difference (P > 0.05) between treatments in protein, fat and carbohydrate contents. Since BP50 was the most efficient treatment, it was also selected for drying of Musa acuminata. Musa acuminata pseudostem had higher moisture, protein, ash and mineral content but no significant difference (P > 0.05) was observed in the fat and carbohydrate values between the two banana species. Practical Applications This paper reveals the most appropriate processing steps (blanching and drying) for pseudostem of two main banana species. Bananas are among the most widely grown crops in the tropical and sub-tropical areas of the world. However, the pseudostem, although consumed in a number of countries, has so far not been considered as a valuable raw material for human nutrition. This paper describes the effects of blanching and drying conditions on the nutritionally useful components for human population.

The bulk density of sliced onions (Allium cepa L., cv. Southport White Globe) at different moisture contents and slice thicknesses was determined by weighing the contents of a cylindrical container of known volume. The void fraction of the samples was estimated from its relationship with apparent and bulk densities. The bulk density and void fraction of onion slices varied non-linearly with moisture content and linearly with slice thickness. For dried onion flakes, the bulk density and void fraction varied non-linearly with slice thickness and moisture content. The experimental results on bulk density and void fraction of onion slices and of dried onion flakes were best explained by second order polynomial models. Using a laboratory apparatus, the resistance to airflow through a bed of the sliced onions of 5 mm initial thickness were measured experimentally and the results at different moisture contents were described well by the modified Ergun equation.