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The protein-chromophore interactions of phycocyanin are prone to changes in environmental conditions. Loss of these interactions leads to disappearance of the color. After stabilization with λ-carrageenan, phycocyanin can be stabilized over 28 days.

Phycocyanin is a protein-chromophore structure present in Arthrospira platensis commonly used as a blue-colorant in food. Color losses of phycocyanin can be reduced by electrostatic complexation with λ-carrageenan. The aim of this study was to investigate the effect of molecular weight (MW) of λ-carrageenan on the color stabilization of electrostatic complexes formed with phycocyanin and λ-carrageenan. Samples were heated to 70 or 90°C at pH 3.0 and stored at 25°C for 14 days. The MW of λ-carrageenan was reduced by ultrasound treatments for 15, 30, 60, and 90 min. Prolonged ultrasonication had a pronounced effect on the Mw, which decreased from 2,341 to 228 kDa (0–90 min). Complexes prepared with low MW λ-carrageenan showed greater color changes compared to complexes prepared with high MW λ-carrageenan. The MW had no visible effect on color stability on day 0, but green/yellow shifts were observed during storage and after heating to 70°C. Medium MW showed less color stabilization effects compared to low MW when heated to 70°C. Moreover, for solutions prepared with ultrasonicated λ-carrageenan, significant hue shifts toward green/yellow, and precipitation were observed after a heat treatment at 90°C. In addition, the sizes of the complexes were significantly reduced (646–102 nm) by using ultrasonicated λ-carrageenan, except for the lowest MW λ-carrageenan when heated to 90°C. Overall, these findings demonstrated that decreasing the MW of λC had adverse effects on the color stability of PC:λC complexes heated to 70 and 90°C.

In the meat industry, hydrocolloids and phosphates are used to improve the quality attributes of meat products. However, latest research results revealed that the usage of exopolysaccharide (EPS)-forming lactic acid bacteria (LAB), which are able to produce EPS in situ during processing could be an interesting alternative. The current review aims to give a better understanding of bacterial EPS production in food matrices with a special focus on meat products. This includes an introduction to microbial EPS production (homopolysaccharides as well as heteropolysaccharides) and an overview of parameters affecting EPS formation and yield depending on LAB used. This is followed by a summary of methods to detect and characterize EPS to facilitate a rational selection of starter cultures and fermentation conditions based on desired structure-function relationships in different food matrices. The mechanism of action of in situ generated EPS is then highlighted with an emphasis on different meat products. In the process, this review also highlights food additives currently used in meat production that could in the future be replaced by in situ EPS-forming LAB. ispartof: COMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY vol:19 issue:6 pages:2932-2954 ispartof: location:United States status: published

The purpose of the study was to investigate the influence of a heteropolysacchride (HePS)-forming lactic acid bacteria (LAB) on the quality attributes of raw fermented sausages. Therefore, salamis with the HePS-producing strain Lactobacillus plantarum TMW 1.1478 or the non-EPS-producing strain Lactobacillus sakei TMW 1.2037 (control) were manufactured using two different inoculation concentrations: more precisely, 10(7) CFU/g (typical starter culture concentration) or 10(9) CFU/g. Growth behavior, a(w) and pH development were recorded until a weight loss of 31% was reached and in-situ-formed EPS detected using confocal laser scanning microscopy. Moreover, the influence of the HePS formed on texture (texture profile analysis; TPA) and sensory attributes (26 panelists, ranking test) was investigated. The final products containing L. plantarum TMW 1.1478 were found to be significantly softer (p

The purpose of the study was to investigate the effect of a reduced pH value (5.1 instead of 5.5 to 5.6) on the properties of highly perishable, spreadable raw fermented sausages (onion mettwurst) with or without the addition of homopolysaccharide (HoPS)-producing lactic acid bacteria (LAB). Hence, sausages with HoPS-producing LAB and a pH value of 5.1 were produced and compared to sausages (pH 5.1) produced with a non-exopolysaccharide (EPS)-forming strain (Lactobacillus sakei TMW 1.2037). Microbial growth and pH values were monitored during processing (24 °C for 48 hr, 10 °C for 24 hr) and storage (14 days at 0 to 2 °C). Furthermore, fat (Weibull-Stoldt) and EPS contents were determined in the final products. Sausages were characterized using texture profile and sensory analysis. The fat contents ranged from 16% to 19% and the determined EPS concentrations ranged from 0.17 to 0.59 g/kg for L. sakei TMW 1.411 and Lactobacillus curvatus TMW 1.1928 and from 0.67 to 1.58 g/kg for L. curvatus TMW 1.51. The strains L. sakei TMW 1.411 and L. curvatus TMW 1.51 reduced the hardness of the samples significantly (P

The pH and temperature sensitivity of the natural blue pigment phycocyanin from Arthrospira platensis limits its application as food colorant. This study examines the effect of protein stabilization by the anionic polysaccharide λ-carrageenan on phycocyanins color appearance at pH 2.5-6.0, unheated and after heat treatments (70/90 °C). Electrostatic interactions, hydrophobic interactions, hydrogen bonds and disulfide-bridges were assessed by adding NaCl, urea and dithiothreitol (DTT) to the samples. Measurements of the zeta potential, transmittance and two-dimensional gel electrophoresis coupled to mass spectrometry confirmed electrostatic interactions around the zero surface charge of phycocyanin over a broad pH range (∼4.1-6.4). Despite a color shift towards turquoise, the color remained stable during heating, especially below of pH 3.5. Precipitation was inhibited over the entire pH range. Overall, electrostatic complexation of phycocyanin and λ-carrageenan is a promising technique to stabilize proteinaceous colorants, helping to reduce food waste and foster a shift to renewable materials.

This study aims to reduce the high fat content of spreadable raw fermented sausages (Teewurst) through the application of in–situ exopolysaccharide (EPS)-forming lactic acid bacteria (LAB). For this reason, sausages with EPS-forming LAB and different fat contents (20–40% added belly fat) were produced and compared to control products without an EPS-forming culture (L. sakei TMW 1.2037). Microbial growth and pH were monitored during processing, the fat (Weibull-Stoldt method) and EPS content (HPLC) of the final products determined, and the products characterized using rheological and texture profile analysis. The fat content of the final products ranged between 17–20%, 25–27%, and 30–33%, respectively. The EPS content of the spreadable raw sausages ranged between 0.08 and 0.30 g/kg for the heteropolysaccharides-producing strain L. plantarum TMW 1.1478, and between 0.46 and 1.03 g/kg for the homopolysaccharide (HoPS)-producing strains L. sakei TMW 1.411 and L. curvatus TMW 1.1928. The latter ones significantly (p This study clearly demonstrated that the application of HoPS-producing LAB is a promising approach to reduce the fat content of spreadable raw fermented sausages.

The influence of oil content and droplet size of oil-in-water emulsions on the heat development in an ohmic heating system was investigated. The setup was run with constant power or voltage. Emulsions consisted of sunflower oil (10–50 wt%), aqua dest. (90–50 wt%) and whey protein isolate (1.25/ 2.5/ 3.75/ 5.0 and 6.25 wt%) Two different droplet size distributions were produced, large (d0.5 ≈ 2.0 μm) and small (d0.5 ≈ 0.3 μm), for each oil mass fraction. The emulsions were ohmically heated from 10 to 80 °C at a constant power of 3.0 kW and constant voltage of 15 V/cm. The electrical conductivity decreased with an increasing oil content, resulting in longer or shorter heating time for constant voltage or constant power input, respectively. The droplet size only affected the heating process at the highest oil content. Industrial relevance Emulsions occur in a wide range of food products (e.g. sauces, dressings, desserts) and have properties giving structure to the food system. Ohmic heating is an emerging thermal process with improved (e.g. faster or less energy required) heating characteristics. The influence of physical changes due to different droplet sizes are of interest because these might also affect the heating characteristic. In addition, the direct comparison of two different process regulations (constant power and constant voltage) indicate which set up is expedient to a successful heating process. This study aims to identify the influence of emulsion-induced structural changes and process changes on the heating rates, which is of interest for the food industry and the related machine building industry.

The antimicrobial efficacy of a fermented spice preparation was assessed in emulsion type sausages and restructured hams and compared to that of two commercially-used antimicrobials; sodium lactate and lauric arginate. Restructured hams and emulsion type sausages were formulated with either sodium lactate (15 × 10 3 μg/g), lauric arginate (N α -lauroyl- l -arginine ethyl ester; LAE; 0.2 × 10 3 μg/g) or a fermented spice preparation (20 × 10 3 μg/g), and effect on microbial growth and sensory properties determined. The spice ferment retarded the growth of Listeria innocua on the surface of emulsion type sausages by about 16 days, while sodium lactate and lauric arginate retarded the growth for 6 and less than 1 days, respectively. On restructured hams, antimicrobial efficacy was lower with growth retardations being 10, 4 and 1 days for the spice ferment, sodium lactate and lauric arginate, respectively. Little activity of all three antimicrobials was found against contamination with Lactobacillus curvatus . No significant deviation in the sensory properties occurred upon addition of antimicrobials to either sausages or hams. Considering that growth of Listeria is one of the key problems in ready to eat meat products, the results are quite promising. Moreover, results suggest that consumers' demands for products without chemical additives may be addressed by exchanging lactate or acetate with fermented spices.

A minced meat model system containing three different fat levels (0, 15, and 50 wt.%) was used to evaluate the antimicrobial efficacy of three antimicrobials with different aqueous solubilities (sodium lactate>lauric arginate (Nα-lauroyl-L-arginine ethyl ester, LAE)>methylparaben). Various concentrations of sodium lactate (20, 40, and 60 mg/g), lauric arginate (0.5, 1, 1.5, 2.0, and 2.5 mg/g) and methylparaben (0.1, 0.5, 1.0, and 2.0 mg/g) were used to evaluate the antimicrobial activity against natural meat microbiota (total aerobic mesophilic colony counts, coliform bacteria, and lactic acid bacteria). The results indicate that the three antimicrobials tested are influenced at different strengths by the changes of the fat addition of the minced meat. The antimicrobial efficacy of LAE and methylparaben is increased by a higher fat content in the meat batter, whereas for lactate no clear lactate proportionality relationship can be seen. This structure sensitivity is most strongly pronounced with lauric arginate, which we attributed to the amphiphilic character of the molecule.

The meat industry often applies hydrocolloids (not label-free) to improve quality attributes of meat products including reconstructed cooked ham. A new approach to improve product quality could be the usage of in-situ Exopolysaccharide (EPS)- forming lactic acid bacteria (LAB) provided that these strains are able to produce EPS in meat matrices under typical processing conditions (here: cooked ham). Two homopolysaccharide- (L. curvatus TMW 1.624 and L. sakei TMW 1.411; 106 CFU mL ) and heteropolysaccharide-forming LABs (L. plantarum TMW 1.1478 and TMW 1.25; 106 CFU mL ) were hence examined for EPS formation in a cooked ham model system consisting of minced pork topside (

Food Processing: Food science and technology is the science that deals with the physical, biological, and chemical processes relevant for the processing of food and food ingredients. The goal is to research, develop, and optimize technical procedures based on natural and engineering sciences as well as socioeconomic factors in order to provide high-quality and safe food for human consumption. Food processing refers to the conversion/transformation of raw materials to a safe food product. This chapter introduces the physical, chemical, and biological unit operations typically used in food processing to ensure food safety and quality. The influence of intrinsic as well as extrinsic parameters on microbial growth behavior is highlighted and examples of important factors that need to be considered during food processing are introduced (water activity, enzyme activity, lipid oxidation). At the end of the chapter, strategies for new product developments are also presented.

Antimicrobials are components added to foods to inhibit microbial growth or inactivate microorganisms. The use of increasingly diverse raw materials coming from a great variety of sources and regions, consumer requirements to process foods minimally to preserve as much of the original character of the raw materials as possible, and the distribution of foods over greater and greater distances, has led to a re-discovery of this traditional approach to food preservation. Nowadays, modern food antimicrobial research focuses on the development of new synthetically derived antimicrobials, or on the discovery of antimicrobially active compounds from natural sources. This has led to the introduction of many new compounds that could be used by food scientists to enhance the quality and safety of food. Unfortunately, many of these antimicrobials demonstrate excellent activities against food pathogens and spoilage organisms in model media but fail to be effective when used in complex foods. This paradox of a high activity in microbial model systems and a low activity in foods as well as the seemingly random extent of such activity losses are still not well understood. This article presents results of some relevant studies that illustrate this phenomena. From those studies, some mechanistic conclusions are derived that may be used to explain this phenomena. These could be used to better forecast activity losses of a particular antimicrobial in a given food system. Finally some conclusions highlighting future research needs are presented.

The antimicrobial efficacy of three antimicrobials with different aqueous solubilities (sodium lactate > lauric arginate (Nα-lauroyl- l -arginine ethyl ester, LAE > methylparaben)) was evaluated. The antimicrobials were added individually, and as binary or ternary mixtures to emulsion type sausages. The antimicrobial efficacy was evaluated against Listeria innocua on the surface of sliced sausages over 24 days of storage at 6 °C. Growth over time was determined, and fitted to a model with a shifted logistic function for evaluation and comparison of antimicrobial effectiveness. The maximum added concentration of LAE (2.0 × 103 μg/g) delayed growth for 1 day. In contrast, lactate and methylparaben (40 and 4.0 × 103 μg/g, respectively) delayed growth for 18 and 7 days, respectively. Five different mixing ratios were investigated for the three different binary combinations: LAE/lactate, LAE/methylparaben and lactate/methylparaben. Results showed that efficacy could be enhanced through mixing of antimicrobials and that the type of antimicrobials as well as their mixing ratio influenced the antimicrobial efficacy of combinations. For ternary combinations, concentrations of two antimicrobials were kept constant while the concentration of the third preservative was varied. To this purpose LAE/methylparaben, LAE/lactate and lactate/methylparaben combinations with concentrations of 0.3/3.3, 0.3/16.7 and 6.6/2.7 × 103 μg/g, respectively, were combined with increasing concentrations of lactate, methylparaben and LAE, respectively. Results indicated that a further increase in activity is possible, albeit there appears to be a critical concentration of the third component below which the ternary combinations were less effective than the binary combinations. Overall our study suggests that combining antimicrobials with different solubilities is a promising approach to enhance shelf life of structurally-complex products such as emulsion type sausages.

UNLABELLED This study evaluated the antimicrobial effect of N(α)-Lauroyl-L-arginine ethyl estermonohydrochloride (lauric arginate), sodium lactate, and sodium diacetate at various concentrations against Listeria innocua, Escherichia coli C600, and Lactobacillus curvatus (10(2) CFU/g) on "Lyoner style" sausage slices as a function of application form. We want to investigate if the results of a surface application of lauric arginate in various applications forms may differ from that of an in-matrix application since different physicochemical processes occur at surfaces than in matrices. Lauric arginate was applied on the surface of meat emulsions as aqueous solution, as oil-in-water emulsion, and as solid lipid particles. The sausages slices were stored at 6 °C for 24 d and bacterial growth was assessed every 3rd day. The growth of L. curvatus was not impacted by lactate and diacetate at any tested concentration. In contrast, L. innocua and E. coli were inhibited over 24 d in the presence of ≥3.0 × 10(3) μg/g diacetate. Aqueous lauric arginate solutions of 2.0 and 2.5 × 10(3) μg/g were required for total inhibition of L. curvatus and L. innocua, respectively. The growth of E. coli was not affected by application of lauric arginate. The use of lauric arginate in an oil-in-water emulsion or solid lipid particles reduced antimicrobial effectiveness on the surface of Lyoner slices, which is in stark contrast to a previously conducted in-matrix application of the same systems. Results were attributed to molecular interactions and mass transport processes that rendered lauric arginate less active when applied as emulsions or solid lipid particles. Results highlight the importance of understanding physicochemical properties when using interfacially active antimicrobials. PRACTICAL APPLICATION This study demonstrates that the antimicrobial efficacy of preservatives in a product depends on the type of preservative and the time of addition at which the preservative is introduced into the production process. Furthermore, application systems for preservatives can indeed prevent unwanted interaction with product ingredients and therefore a loss of antimicrobial activity but also in this case the time of addition is critical because the preservative must have the possibility to separate from the carrier system.

Lauric arginate (LAE) is a food-grade cationic surfactant that is highly active against a wide range of food pathogens (Listeria monocytogenes, Salmonella, and Escherichia coli) and food spoilers (Lactobacilli, yeast, and molds). The antimicrobial efficacy of LAE in compositionally complex environments is likely to be negatively impacted by its interactions with food ingredients. Therefore, we investigated different application systems of LAE and their impact on its antimicrobial efficacy when added to “Lyoner style” sausages. LAE was applied as a powder, aqueous solution, in oil-in-water emulsions with different droplet sizes, and as solid lipid particles (SLP) with different droplet sizes. Structures of the systems were identified by optical microscopy, differential scanning calorimetry (DSC) and static light scattering. A recontamination on the surface of sliced sausages was simulated using Listeria innocua as the target organism (2 log colony forming units (CFU)/slice), and the antimicrobial impact of 1,000, 1,500 and 2,000 μg/g applied LAE in the sausage was examined by growth curves. A modeling of the CFU-time relationship was carried out to provide a better evaluation of the antimicrobial activity of LAE. Finally, we carried out an isothermal titration calorimetry (ITC) analysis to simulate the interactions between LAE and proteins in the sausage matrix. Results revealed that the application systems differed in their surface area and, therefore, showed different antimicrobial activities when incorporated into sausage. The study demonstrated that the SLP and emulsions as LAE application systems increased the antimicrobial activity against microbial growth on the surface of sliced “Lyoner style” sausages.

The antimicrobial activity of oil-in-water emulsions containing dual combinations of the essential oil components cinnamaldehyde, perillaldehyde, and citral was examined against two acid-resistant yeast strains (Zygosaccharomyces bailii) in beverage systems composed of diluted clear or cloudy apple juice and in a Sabouraud dextrose broth model. Antimicrobial properties of an encapsulated oil-in-water emulsion and of essential oil components dissolved in 10% dimethyl sulfoxide were compared using plate counts and turbidity measurements. Growth curves were modulated to qualitatively assess differences in antimicrobial efficacy. The impact of the presence of a beverage emulsion without essential oils (unloaded; 5% oil and 1% modified starch, pH 3.0) on the antimicrobial efficacy also was investigated. Dual combinations of essential oil components were sufficient to completely inhibit and/or kill yeast cells in diluted apple juice and Sabouraud dextrose broth systems at very low concentrations (100 to 200 μg/ml). However, the combination of perillaldehyde and citral had the weakest antimicrobial effect; a concentration of 400 μg/ml was necessary to prevent yeast growth in beverages, and up to 800 μg/ml was required in systems to which an unloaded emulsion had been added. The antimicrobial activity of essential oil components did not differ in diluted clear and cloudy apple juices and was not affected by being added in emulsified form or dissolved in dimethyl sulfoxide as long as there was no unloaded emulsion also present. These results indicate that formulations of essential oil combinations encapsulated together in emulsions are highly effective for inhibiting and/or killing microorganisms in real beverage systems.

This study evaluated the antimicrobial effect of N(α)-Lauroyl-L-arginine ethyl estermonohydrochloride (lauric arginate), sodium lactate, and sodium diacetate at various concentrations against Listeria innocua, Escherichia coli C600, and Lactobacillus curvatus (10(2) CFU/g) on "Lyoner style" sausage slices as a function of application form. We want to investigate if the results of a surface application of lauric arginate in various applications forms may differ from that of an in-matrix application since different physicochemical processes occur at surfaces than in matrices. Lauric arginate was applied on the surface of meat emulsions as aqueous solution, as oil-in-water emulsion, and as solid lipid particles. The sausages slices were stored at 6 °C for 24 d and bacterial growth was assessed every 3rd day. The growth of L. curvatus was not impacted by lactate and diacetate at any tested concentration. In contrast, L. innocua and E. coli were inhibited over 24 d in the presence of ≥3.0 × 10(3) μg/g diacetate. Aqueous lauric arginate solutions of 2.0 and 2.5 × 10(3) μg/g were required for total inhibition of L. curvatus and L. innocua, respectively. The growth of E. coli was not affected by application of lauric arginate. The use of lauric arginate in an oil-in-water emulsion or solid lipid particles reduced antimicrobial effectiveness on the surface of Lyoner slices, which is in stark contrast to a previously conducted in-matrix application of the same systems. Results were attributed to molecular interactions and mass transport processes that rendered lauric arginate less active when applied as emulsions or solid lipid particles. Results highlight the importance of understanding physicochemical properties when using interfacially active antimicrobials.This study demonstrates that the antimicrobial efficacy of preservatives in a product depends on the type of preservative and the time of addition at which the preservative is introduced into the production process. Furthermore, application systems for preservatives can indeed prevent unwanted interaction with product ingredients and therefore a loss of antimicrobial activity but also in this case the time of addition is critical because the preservative must have the possibility to separate from the carrier system.

Aims To investigate the effect of anionic polysaccharides often used in beverage applications (xanthan and λ-carrageenan) on the antimicrobial efficacy of the cationic surfactant lauric arginate (LAE) against typical spoilage yeasts. Methods and Results The antimicrobial efficacy of LAE against Saccharomyces cerevisiae, Candida albicans and Zygosaccharomyces bailii in the absence and presence of anionic polysaccharides was assessed by microtitre and macrobroth dilution assays. Combining LAE with either xanthan or λ-carrageenan caused a pronounced decrease in LAE's antimicrobial efficacy, with the minimal inhibitory and lethal concentrations (MIC and MLC) both increasing with increasing polysaccharide concentration. This reduction in antimicrobial efficacy was more pronounced for the addition of λ-carrageenan. To determine the cause of loss of activity, physical properties of solutions were examined. Turbidity and sedimentation measurements indicated that complexes between LAE and anionic polysaccharides had been formed. Electrophoresis measurements showed that complexes had varying electrical charges and dimensions depending on solution composition. Conclusion Results suggest that electrostatic interactions between LAE and anionic polysaccharides play a major role in complex formation and loss of antimicrobial activity. Significance and Impact of the Study Results have important implications for the utilization of LAE as an antimicrobial agent in beverage and food products containing anionic polysaccharides.