Bacteriocin production by lactic acid bacteria using ice cream co-product as the fermentation substrate.

Ice cream manufacture commonly results in the accumulation of wasted product which contains valuable food-grade quality components including fat, carbohydrates, and protein. Methods have been developed for recovering the fat from this waste stream, but this results in the generation of a co-product rich in fermentable carbohydrates. This study aimed to investigate the potential for using this co-product as a fermentation substrate for production of antimicrobial peptides, called bacteriocins, by dairy starter cultures. Results showed that Streptococcus thermophilus B59671 and Lactococcus lactis 11454 produced the broad spectrum bacteriocins thermophilin 110 and nisin, respectively, when the fermentation substrate was melted ice cream, or a co-product generated by a modified butter churning technique. Bacteriocin production varied depending on the brand and variety of vanilla ice cream used in this study. When an alternate enzyme-assisted fat extraction technique was utilized, S. thermophilus metabolism was impaired within the resulting co-product, and thermophilin 110 production was not observed. L. lactis was still able to grow in this co-product, but antimicrobial activity was not observed. Results from this study suggest the co-product generated when using the churning technique is a better choice to use as a base medium for future studies to optimize bacteriocin production.

Lacticaseibacillus rhamnosus Strain GG (LGG) Regulate Gut Microbial Metabolites, an In Vitro Study Using Three Mature Human Gut Microbial Cultures in a Simulator of Human Intestinal Microbial Ecosystem (SHIME).

In the present research, we investigated changes in the gut metabolome that occurred in response to the administration of the Laticaseibacillus rhamnosus strain GG (LGG). The probiotics were added to the ascending colon region of mature microbial communities established in a human intestinal microbial ecosystem simulator. Shotgun metagenomic sequencing and metabolome analysis suggested that the changes in microbial community composition corresponded with changes to metabolic output, and we can infer linkages between some metabolites and microorganisms. The in vitro method permits a spatially-resolved view of metabolic transformations under human physiological conditions. By this method, we found that tryptophan and tyrosine were mainly produced in the ascending colon region, while their derivatives were detected in the transverse and descending regions, revealing sequential amino acid metabolic pathways along with the colonic tract. The addition of LGG appeared to promote the production of indole propionic acid, which is positively associated with human health. Furthermore, the microbial community responsible for the production of indole propionic acid may be broader than is currently known.

Associations among Milk Microbiota, Milk Fatty Acids, Milk Glycans, and Inflammation from Lactating Holstein Cows.

Milk oligosaccharides (MOs) can be prebiotic and antiadhesive, while fatty acids (MFAs) can be antimicrobial. Both have been associated with milk microbes or mammary gland inflammation in humans. Relationships between these milk components and milk microbes or inflammation have not been determined for cows and could help elucidate a novel approach for the dairy industry to promote desired milk microbial composition for improvement of milk quality and reduction of milk waste. We aimed to determine relationships among milk microbiota, MFAs, MOs, lactose, and somatic cell counts (SCC) from Holstein cows, using our previously published data. Raw milk samples were collected at three time points, ranging from early to late lactation. Data were analyzed using linear mixed-effects modeling and repeated-measures correlation. Unsaturated MFA and short-chain MFA had mostly negative relationships with potentially pathogenic genera, including Corynebacterium, Pseudomonas, and an unknown Enterobacteriaceae genus but numerous positive relationships with symbionts Bifidobacterium and Bacteroides. Conversely, many MOs were positively correlated with potentially pathogenic genera (e.g., Corynebacterium, Enterococcus, and Pseudomonas), and numerous MOs were negatively correlated with the symbiont Bifidobacterium. The neutral, nonfucosylated MO composed of eight hexoses had a positive relationship with SCC, while lactose had a negative relationship with SCC. One interpretation of these trends might be that in milk, MFAs disrupt primarily pathogenic bacterial cells, causing a relative increase in abundance of beneficial microbial taxa, while MOs respond to and act on pathogenic taxa primarily through antiadhesive methods. Further research is needed to confirm the potential mechanisms driving these correlations. IMPORTANCE Bovine milk can harbor microbes that cause mastitis, milk spoilage, and foodborne illness. Fatty acids found in milk can be antimicrobial and milk oligosaccharides can have antiadhesive, prebiotic, and immune-modulatory effects. Relationships among milk microbes, fatty acids, oligosaccharides, and inflammation have been reported for humans. To our knowledge, associations among the milk microbial composition, fatty acids, oligosaccharides, and lactose have not been reported for healthy lactating cows. Identifying these potential relationships in bovine milk will inform future efforts to characterize direct and indirect interactions of the milk components with the milk microbiota. Since many milk components are associated with herd management practices, determining if these milk components impact milk microbes may provide valuable information for dairy cow management and breeding practices aimed at minimizing harmful and spoilage-causing microbes in raw milk.

Encapsulation of Lactobacillus rhamnosus GG in edible electrospun mats from calcium and sodium caseinates with pullulan blends.

Electrospinning has been proposed as a method to encapsulate and preserve bioactive compounds in nanofibrous mats to ensure their delivery and associated health benefits when consumed directly or added to a food formulation. In previous work, we demonstrated the production of edible fibers to form mats of both calcium (CaCAS) and sodium (NaCAS) caseinate-pullulan (PUL), with the polysaccharide PUL added as a carrier to facilitate molecular entanglement for fiber formation. In this study, we determined the viability of the probiotic bacteria, Lactobacillus rhamnosus GG (LGG), used as a model bacterium, in mats of CaCAS-PUL and NaCAS-PUL. Electrospinning of aqueous solutions at room temperature (21 ± 1°C) of 15% (wt/wt) CaCAS and NaCAS mixed with 15% (wt/wt) PUL, with a 1:1 ratio of CAS:PUL, resulted in fibrous mats with average fiber diameter sizes of 233 ± 20 and 244 ± 21 nm, respectively, as determined by scanning electron microscopy. Addition of LGG in the amounts of 9.3 and 9.0 log10 cfu/mL to the CaCAS-PUL and NaCAS-PUL solutions before electrospinning resulted in average fiber diameter sizes of 212 ± 14 and 286 ± 16 nm, respectively. The LGG was found to be distributed within the CaCAS-PUL and NaCAS-PUL fibers. The addition of LGG increased the shear viscosity and conductivity of the CaCAS-PUL solution, enhancing molecular entanglement and resulting in thinner fibers. For NaCAS, LGG increased the conductivity but reduced shear viscosity. Adjustment of the NaCAS-PUL composition would be needed to optimize conditions for thinner fibers. The numbers of viable LGG recovered from the CaCAS-PUL and NaCAS-PUL nanofibrous mats after electrospinning were 9.5 and 9.6 log10 cfu/g, respectively, proving that the electrospinning conditions used were capable of supporting probiotic encapsulation. These results demonstrate that food-grade electrospun fibrous mats can be used to develop functional foods with delivery of probiotics to improve human or animal health.

Persistence of the Probiotic Lacticaseibacillus rhamnosus Strain GG (LGG) in an In Vitro Model of the Gut Microbiome.

The consumption of probiotics is widely encouraged due to reports of their positive effects on human health. In particular, Lacticaseibacillus rhamnosus strain GG (LGG) is an approved probiotic that has been reported to improve health outcomes, especially for gastrointestinal disorders. However, how LGG cooperates with the gut microbiome has not been fully explored. To understand the interaction between LGG and its ability to survive and grow within the gut microbiome, this study introduced LGG into established microbial communities using an in vitro model of the colon. LGG was inoculated into the simulated ascending colon and its persistence in, and transit through the subsequent transverse and descending colon regions was monitored over two weeks. The impact of LGG on the existing bacterial communities was investigated using 16S rRNA sequencing and short-chain fatty acid analysis. LGG was able to engraft and proliferate in the ascending region for at least 10 days but was diminished in the transverse and descending colon regions with little effect on short-chain fatty acid abundance. These data suggest that the health benefits of the probiotic LGG rely on its ability to transiently engraft and modulate the host microbial community.

Improvement of physicochemical properties of reduced-cholesterol butter by the addition of ß-sitosteryl oleate.

Beta-cyclodextrin (ß-CD) has been shown to successfully lower the cholesterol content of dairy products, such as butter, but the process tends to negatively impact the overall quality and consistency. In this study, ß-sitosterol, which is similar in structure as cholesterol, was reacted with oleic acid to form ß-sitosteryl oleate (BSO), and this was used to improve the consistency of reduced-cholesterol butter. The reaction was catalyzed by sodium bisulfate (2%, w/w) at 140 °C, and the highest degree of esterification (94.3%) was obtained after 9 hr of reaction using a ß-sitosterol-oleic acid molar ratio of 1:5. Ultra-pasteurized cream was then treated with 15% (w/v) ß-CD at 40 °C with stirring (100 rpm), for 30 min. Results indicated a 95.4% reduction in cholesterol content. Finally, the reduced-cholesterol cream was constituted to contain 3, 5, and 10% (w/w) BSO, after which fat was extracted from the three formulations and their melting profiles compared to that of milk fat. The cream containing 3% BSO showed a profile similar to milk fat and was, therefore, used to formulate BSO-incorporated reduced-cholesterol butter (BSOB). Instrumental analyses showed that BSOB was comparable to the control butter with respect to physical properties, such as hardness/firmness and adhesiveness. PRACTICAL APPLICATION: A modified plant sterol, beta-sitosteryl oleate, was incorporated into a reduced-cholesterol butter to improve its physicochemical properties. The reduced-cholesterol butter was comparable to regular butter with respect to its consistency and melting properties and could be made into sticks. In addition to the reduced-cholesterol butter, this product could provide the foundation for new products blending butter and oils to create other low-cholesterol, reduced saturated-fat products, possibly in stick form.

Impact of Steviol Glycosides and Erythritol on the Human and Cebus apella Gut Microbiome.

Leaf extracts of Stevia rebaudiana, composed of more than 10 steviol glycosides (SGs), are used as non-nutritive, table sugar (sucrose) alternatives due to their high level of sweetness and low caloric impact. They are often combined with the sugar alcohol erythritol to increase volume and reduce aftertaste. Little is known of the impact of sugar alternatives on the human gut microbiota in terms of the diversity, composition, and metabolic products. Testing of SGs and erythritol using six representatives of the gut microbiota in vitro found no impact on bacterial growth, yet treatment with erythritol resulted in an enhancement of butyric and pentanoic acid production when tested using a human gut microbial community. Furthermore, administration of SGs and erythritol to a Cebus apella model resulted in changes to the gut microbial structure and diversity. Overall, the study did not find a negative impact of SGs and erythritol on the gut microbial community.

Establishing a mucosal gut microbial community in vitro using an artificial simulator.

The Twin Simulator of the Human Intestinal Microbial Ecosystem (TWINSHIME®) was initially developed to study the luminal gut microbiota of the ascending (AC), transverse (TC), and descending (DC) colon regions. Given the unique composition and potential importance of the mucosal microbiota for human health, the TWINSHIME was recently adapted to simulate the mucosal microbiota as well as the luminal community. It has been previously demonstrated that the luminal community in the TWINSHIME reaches a steady state within two weeks post inoculation, and is able to differentiate into region specific communities. However, less is known regarding the mucosal community structure and dynamics. During the current study, the luminal and mucosal communities in each region of the TWINSHIME were evaluated over the course of six weeks. Based on 16S rRNA gene sequencing and short chain fatty acid analysis, it was determined that both the luminal and mucosal communities reached stability 10-20 days after inoculation, and remained stable until the end of the experiment. Bioinformatics analysis revealed the formation of unique community structures between the mucosal and luminal phases in all three colon regions, yet these communities were similar to the inoculum. Specific colonizers of the mucus mainly belonged to the Firmicutes phylum and included Lachnospiraceae (AC/TC/DC), Ruminococcaceae and Eubacteriaceae (AC), Lactobacillaceae (AC/TC), Clostridiaceae and Erysipelotrichaceae (TC/DC). In contrast, Bacteroidaceae were enriched in the gut lumen of all three colon regions. The unique profile of short chain fatty acid (SCFA) production further demonstrated system stability, but also proved to be an area of marked differences between the in vitro system and in vivo reports. Results of this study demonstrate that it is possible to replicate the community structure and composition of the gut microbiota in vitro. Through implementation of this system, the human gut microbiota can be studied in a dynamic and continuous fashion.

Electrospun ultra-fine cellulose acetate fibrous mats containing tannic acid-Fe3+ complexes.

Cellulose acetate (CA) fibrous mats with improved mechanical and antioxidant properties were produced by a simple, scalable and cost-effective electrospinning method. Fibers loaded with small amounts of TA-Fe3+ complexes showed an increase in tensile strength of ∼117% when compared to that of neat CA and were more resistant than those loaded with TA alone. The water uptake of the fibers increased upon TA or TA-Fe3+ incorporation while their thermal behavior was only slightly affected. Fibrous mats loaded with TA-Fe3+ showed comparable antioxidant activity with that of CA/TA mats, and a much slower TA release. These results suggest that TA-Fe3+ complexes can be incorporated into electrospun CA fibers to improve their mechanical properties and antioxidant activity which may be of interest for the development of active packaging that can extend the shelf life of perishable foods.

Effect of heat and homogenization on in vitro digestion of milk.

Central to commercial fluid milk processing is the use of high temperature, short time (HTST) pasteurization to ensure the safety and quality of milk, and homogenization to prevent creaming of fat-containing milk. Ultra-high-temperature sterilization is also applied to milk and is typically used to extend the shelf life of refrigerated, specialty milk products or to provide shelf-stable milk. The structures of the milk proteins and lipids are affected by processing but little information is available on the effects of the individual processes or sequences of processes on digestibility. In this study, raw whole milk was subjected to homogenization, HTST pasteurization, and homogenization followed by HTST or UHT processing. Raw skim milk was subjected to the same heating regimens. In vitro gastrointestinal digestion using a fasting model was then used to detect the processing-induced changes in the proteins and lipids. Using sodium dodecyl sulfate-PAGE, gastric pepsin digestion of the milk samples showed rapid elimination of the casein and α-lactalbumin bands, persistence of the ß-lactoglobulin bands, and appearance of casein and whey peptide bands. The bands for ß-lactoglobulin were eliminated within the first 15min of intestinal pancreatin digestion. The remaining proteins and peptides of raw, HTST, and UHT skim samples were digested rapidly within the first 15min of intestinal digestion, but intestinal digestion of raw and HTST pasteurized whole milk showed some persistence of the peptides throughout digestion. The availability of more lipid droplets upon homogenization, with greater surface area available for interaction with the peptides, led to persistence of the smaller peptide bands and thus slower intestinal digestion when followed by HTST pasteurization but not by UHT processing, in which the denatured proteins may be more accessible to the digestive enzymes. Homogenization and heat processing also affected the ζ-potential and free fatty acid release during intestinal digestion. Stearic and oleic acids were broken down faster than other fatty acids due to their positions on the outside of the triglyceride molecule. Five different casein phosphopeptide sequences were observed after gastric digestion, and 31 sequences were found after intestinal digestion, with activities yet to be explored. Processing affects milk structure and thus digestion and is an important factor to consider in design of foods that affect health and nutrition.

Preserving viability of Lactobacillus rhamnosus GG in vitro and in vivo by a new encapsulation system.

Probiotics have shown beneficial effects on health and prevention of diseases in humans. However, a concern for application of probiotics is the loss of viability during storage and gastrointestinal transit. The aim of this study was to develop an encapsulation system to preserve viability of probiotics when they are administrated orally and apply Lactobacillus rhamnosus GG (LGG) as a probiotic model to evaluate the effectiveness of this approach using in vitro and in vivo experiments. LGG was encapsulated in hydrogel beads prepared using pectin, a food grade polysaccharide, glucose, and calcium chloride, and lyophilized by freeze-drying. Encapsulated LGG was cultured in vitro under the condition that mimicked the physiological environment of the human gastrointestinal tract. Compared to non-encapsulated LGG, encapsulation increased tolerance of LGG in the acid condition, protected LGG from protease digestion, and improved shelf time when stored at the ambient condition, in regard of survivability and production of p40, a known LGG-derived protein involved in LGG's beneficial effects on intestinal homeostasis. To evaluate the effects of encapsulation on p40 production in vivo and prevention of intestinal inflammation by LGG, mice were gavaged with LGG containing beads and treated with dextran sulphate sodium (DSS) to induce intestinal injury and colitis. Compared to non-encapsulated LGG, encapsulated LGG enhanced more p40 production in mice, and exerted higher levels of effects on prevention of DSS-induced colonic injury and colitis and suppression of pro-inflammatory cytokine production. These data indicated that the encapsulation system developed in this study preserves viability of LGG in vitro and in vivo, leading to longer shelf time and enhancing the functions of LGG in the gastrointestinal tract. Thus, this encapsulation approach may have the potential application for improving efficacy of probiotics.

Physical and chemical changes in whey protein concentrate stored at elevated temperature and humidity.

In a case study, we monitored the physical properties of 2 batches of whey protein concentrate (WPC) under adverse storage conditions to provide information on shelf life in hot, humid areas. Whey protein concentrates with 34.9 g of protein/100g (WPC34) and 76.8 g of protein/100g (WPC80) were stored for up to 18 mo under ambient conditions and at elevated temperature and relative humidity. The samples became yellower with storage; those stored at 35 °C were removed from the study by 12 mo because of their unsatisfactory appearance. Decreases in lysine and increases in water activity, volatile compound formation, and powder caking values were observed in many specimens. Levels of aerobic mesophilic bacteria, coliforms, yeast, and mold were <3.85 log10 cfu/g in all samples. Relative humidity was not a factor in most samples. When stored in sealed bags, these samples of WPC34 and WPC80 had a shelf life of 9 mo at 35 °C but at least 18 mo at lower temperatures, which should extend the market for these products.

Electrospun Polymer Nanofibers Reinforced by Tannic Acid/Fe+++ Complexes.

We report the successful preparation of reinforced electrospun nanofibers and fibrous mats of polyvinyl alcohol (PVA) via a simple and inexpensive method using stable tannic acid (TA) and ferric ion (Fe+++) assemblies formed by solution mixing and pH adjustment. Changes in solution pH change the number of TA galloyl groups attached to the Fe+++ from one (pH < 2) to two (3 < pH < 6) to three (pH < 7.4) and affect the interactions between PVA and TA. At pH ~ 5.5, the morphology and fiber diameter size (FDS) examined by SEM are determinant for the mechanical properties of the fibrous mats and depend on the PVA content. At an optimal 8 wt % concentration, PVA becomes fully entangled and forms uniform nanofibers with smaller FDS (p < 0.05) and improved mechanical properties when compared to mats of PVA alone and of PVA with TA (p < 0.05). Changes in solution pH lead to beads formation, more irregular FDS and poorer mechanical properties (p < 0.05). The Fe+++ inclusion does not alter the oxidation activity of TA (p > 0.05) suggesting the potential of TA-Fe+++ assemblies to reinforce polymer nanofibers with high functionality for use in diverse applications including food, biomedical and pharmaceutical.

Two methods for increased specificity and sensitivity in loop-mediated isothermal amplification.

The technique of loop-mediated isothermal amplification (LAMP) utilizes four (or six) primers targeting six (or eight) regions within a fairly small segment of a genome for amplification, with concentration higher than that used in traditional PCR methods. The high concentrations of primers used leads to an increased likelihood of non-specific amplification induced by primer dimers. In this study, a set of LAMP primers were designed targeting the prfA gene sequence of Listeria monocytogenes, and dimethyl sulfoxide (DMSO) as well as Touchdown LAMP were employed to increase the sensitivity and specificity of the LAMP reactions. The results indicate that the detection limit of this novel LAMP assay with the newly designed primers and additives was 10 fg per reaction, which is ten-fold more sensitive than a commercial Isothermal Amplification Kit and hundred-fold more sensitive than previously reported LAMP assays. This highly sensitive LAMP assay has been shown to detect 11 strains of Listeria monocytogenes, and does not detect other Listeria species (including Listeria innocua and Listeria invanovii), providing some advantages in specificity over commercial Isothermal Amplification Kits and previously reported LAMP assay.

Effect of homogenization and pasteurization on the structure and stability of whey protein in milk.

The effect of homogenization alone or in combination with high-temperature, short-time (HTST) pasteurization or UHT processing on the whey fraction of milk was investigated using highly sensitive spectroscopic techniques. In pilot plant trials, 1-L quantities of whole milk were homogenized in a 2-stage homogenizer at 35°C (6.9 MPa/10.3 MPa) and, along with skim milk, were subjected to HTST pasteurization (72°C for 15 s) or UHT processing (135°C for 2 s). Other whole milk samples were processed using homogenization followed by either HTST pasteurization or UHT processing. The processed skim and whole milk samples were centrifuged further to remove fat and then acidified to pH 4.6 to isolate the corresponding whey fractions, and centrifuged again. The whey fractions were then purified using dialysis and investigated using the circular dichroism, Fourier transform infrared, and Trp intrinsic fluorescence spectroscopic techniques. Results demonstrated that homogenization combined with UHT processing of milk caused not only changes in protein composition but also significant secondary structural loss, particularly in the amounts of apparent antiparallel ß-sheet and α-helix, as well as diminished tertiary structural contact. In both cases of homogenization alone and followed by HTST treatments, neither caused appreciable chemical changes, nor remarkable secondary structural reduction. But disruption was evident in the tertiary structural environment of the whey proteins due to homogenization of whole milk as shown by both the near-UV circular dichroism and Trp intrinsic fluorescence. In-depth structural stability analyses revealed that even though processing of milk imposed little impairment on the secondary structural stability, the tertiary structural stability of whey protein was altered significantly. The following order was derived based on these studies: raw whole>HTST, homogenized, homogenized and pasteurized>skimmed and pasteurized, and skimmed UHT>homogenized UHT. The methodology demonstrated in this study can be used to gain insight into the behavior of milk proteins when processed and provides a new empirical and comparative approach for analyzing and assessing the effect of processing schemes on the nutrition and quality of milk and dairy product without the need for extended separation and purification, which can be both time-consuming and disruptive to protein structures.

Enrichment and Purification of Casein Glycomacropeptide from Whey Protein Isolate Using Supercritical Carbon Dioxide Processing and Membrane Ultrafiltration.

Whey protein concentrates (WPC) and isolates (WPI), comprised mainly of ß-lactoglobulin (ß-LG), α-lactalbumin (α-LA) and casein glycomacropeptide (GMP), are added to foods to boost nutritional and functional properties. Supercritical carbon dioxide (SCO2) has been shown to effectively fractionate WPC and WPI to obtain enriched fractions of α-LA and ß-LG, thus creating new whey ingredients that exploit the properties of the individual component proteins. In this study, we used SCO2 to further fractionate WPI via acid precipitation of α-LA, ß-LG and the minor whey proteins to obtain GMP-enriched solutions. The process was optimized and α-LA precipitation maximized at low pH and a temperature (T) ≥65 °C, where ß-LG with 84% purity and GMP with 58% purity were obtained, after ultrafiltration and diafiltration to separate ß-LG from the GMP solution. At 70 °C, ß-LG also precipitated with α-LA, leaving a GMP-rich solution with up to 94% purity after ultrafiltration. The different protein fractions produced with the SCO2 process will permit the design of new foods and beverages to target specific nutritional needs.

Fractionation of whey protein isolate with supercritical carbon dioxide to produce enriched α-lactalbumin and ß-lactoglobulin food ingredients.

An environmentally friendly protein fractionation process using supercritical carbon dioxide (SCO(2)) as an acid was developed to produce enriched α-lactalbumin (α-LA) and ß-lactoglobulin (ß-LG) fractions from whey protein isolate solutions containing from 2 to 10% WPI. This study investigated the effects of pH, temperature, WPI concentration, and residence time on the precipitation kinetics and recovery yields of individual whey proteins and the relative enrichment and composition of both protein fractions. At 5.5-34 MPa and 60-65 °C, solubilized SCO(2) decreased solution pH and induced the formation and precipitation of α-LA aggregates. Gel electrophoresis and HPLC of the enriched fractions demonstrated the production of ≥ 60% pure α-LA, and ≥ 70% pure ß-LG, under various operating conditions, from WPI containing ∼57% ß-LG and 21% α-LA. The enriched fractions are ready-to-use food ingredients with neutral pH, untainted by acids and contaminants.

Fractionation of whey protein isolate with supercritical carbon dioxide-process modeling and cost estimation.

An economical and environmentally friendly whey protein fractionation process was developed using supercritical carbon dioxide (sCO(2)) as an acid to produce enriched fractions of α-lactalbumin (α-LA) and ß-lactoglobulin (ß-LG) from a commercial whey protein isolate (WPI) containing 20% α-LA and 55% ß-LG, through selective precipitation of α-LA. Pilot-scale experiments were performed around the optimal parameter range (T = 60 to 65 °C, P = 8 to 31 MPa, C = 5 to 15% (w/w) WPI) to quantify the recovery rates of the individual proteins and the compositions of both fractions as a function of processing conditions. Mass balances were calculated in a process flow-sheet to design a large-scale, semi-continuous process model using SuperproDesigner® software. Total startup and production costs were estimated as a function of processing parameters, product yield and purity. Temperature, T, pressure, P, and concentration, C, showed conflicting effects on equipment costs and the individual precipitation rates of the two proteins, affecting the quantity, quality, and production cost of the fractions considerably. The highest α-LA purity, 61%, with 80% α-LA recovery in the solid fraction, was obtained at T = 60 °C, C = 5% WPI, P = 8.3 MPa, with a production cost of $8.65 per kilogram of WPI treated. The most profitable conditions resulted in 57%-pure α-LA, with 71% α-LA recovery in the solid fraction and 89% ß-LG recovery in the soluble fraction, and production cost of $5.43 per kilogram of WPI treated at T = 62 °C, C = 10% WPI and P = 5.5 MPa. The two fractions are ready-to-use, new food ingredients with a pH of 6.7 and contain no residual acid or chemical contaminants.

Mitigation of greenhouse gas emissions in the production of fluid milk.

Global climate change, driven by the buildup of greenhouse gas (GHG) emissions in the atmosphere, is challenging the dairy industries in the United States and throughout the world to develop sustainable initiatives to reduce their environmental impact. The U.S. dairy industry has committed to lowering the GHG emissions, primarily CH(4), N(2)O, and CO(2), in each sector of the fluid milk supply chain which extends from the farm, to the processing plant, and to distribution of the packaged product, where it is refrigerated by the retailer and then the consumer. This chapter provides an overview of the life cycle analysis (LCA) technique and its use in identifying the GHG emissions in each sector of the fluid milk supply chain, from cradle to grave, and the best practices and research that is currently being conducted to reduce or mitigate GHG emissions in each sector. We also discuss the use of on-farm and off-farm process simulation as tools for evaluating on-farm mitigation techniques, off-farm alternative processing scenarios, and use of alternative energy management practices.

Removal of Salmonella Enteritidis from commercial unpasteurized liquid egg white using pilot scale cross flow tangential microfiltration.

Effectiveness of a cross flow microfiltration (MF) process for removal of a cocktail of Salmonella enterica serovar Enteritidis species from commercial unpasteurized liquid egg white (LEW) from a local egg breaking plant, while maintaining its functional properties was evaluated. To facilitate MF, LEW was wedge screened, homogenized and then diluted (1:2 w/w) with distilled water containing 0.5% sodium chloride. Diluted unpasteurized LEW was inoculated with five strains of S. Enteritidis (ATCC 4931, ATCC BAA-708, ATCC 49215, ATCC 49218, and ATCC BAA-1045) to a level of approximately 10(7)CFU/mL of LEW and microfiltered using a ceramic membrane. Process parameters influencing egg white functional properties and pathogen removal efficiency were evaluated. Average permeates flux increased by almost 126% when pH of LEW was adjusted from pH 8 to pH 7 at 25 degrees C. Microbial removal efficiency was at least, on average, 6.8Log(10)CFU/mL (limit of detection < or =0.5Log(10)CFU/mL). Functional property analysis indicated that the MF process did not alter the foaming power of LEW.