Physicochemical and nitrogen solubility properties of Bacillus proteinase hydrolysates of sodium caseinate incubated with transglutaminase pre- and post-hydrolysis

Incorporation of bioactive dairy hydrolysate influences the stability and digestion behaviour of milk protein stabilised emulsions

The physical stability of emulsions containing bioactive ingredients is an important aspect of functional food development. This research investigated the effects of a bioactive dairy hydrolysate with anti-inflammatory effects on the properties of oil-in-water emulsions (23% rapeseed oil and 1.5% w/w protein). This was determined by monitoring the effects of various combinations of sodium caseinate (NaCas) and NaCas hydrolysate (NaCasH) (NaCas : NaCasH; 100 : 0, 40 : 60, 30 : 70, 20 : 80 and 0 : 100) on the physico-chemical characteristics (particle size distribution, microstructure, adsorption of protein to the interface, viscosity and creaming stability) of emulsions. Currently, there is growing interest in designing functional foods that modulate lipid digestion. Therefore, emulsion breakdown and subsequent release of free fatty acids (FFAs) from selected NaCasH stabilised emulsions (40 : 60 and 0 : 100) was monitored during in vitro gastrointestinal digestion and compared to the behaviour of emulsions stabilised by NaCas alone. Inclusion of NaCasH generally decreased the stability of the emulsions except when added at a NaCas : NaCasH ratio of 40 : 60 which resulted in emulsions with equivalent stability to the NaCas stabilised emulsions. Although the 40 : 60 combination provided an emulsion system as stable as NaCas, during simulated digestion, these emulsions demonstrated a slower rate of FFA release. This was attributed to the 40 : 60 stabilised emulsions having much larger flocculated lipid droplets than NaCas emulsions, which resulted in reduced surface area and fewer binding sites for lipase adsorption. Accordingly, the 40 : 60 emulsions were hydrolysed more slowly. Emulsions containing only NaCasH exhibited extensive coalescence prior to and during digestion and thus displayed the slowest release of FFA. The results suggest that including NaCasH in the emulsifier blend yields emulsions with modified digestibility and may form the basis of controlling the digestion and release of fat-soluble nutrients in formulated foods. However, further studies are required to optimise the stability of these emulsions before inclusion in such applications.

Pepsin-Assisted Transglutaminase Modification of Functional Properties of a Protein Isolate Obtained from Industrial Sunflower Meal

The utilization of industrial sunflower meal to produce protein-rich products for the food industry is an alternative approach for better and more efficient use of this agricultural by-product. Sunflower meal proteins possess specific functional properties, which however need improvement to broaden their potential as supplements for delivering high--quality products for human nutrition. The aim of the study is to evaluate the combined influence of low-degree pepsin hydrolysis and transglutaminase (TG) modification on industrial sunflower meal protein isolate functionality at pH=2 to 10. Three TG-modified pepsin hydrolysates with the degree of hydrolysis of 0.48, 0.71 and 1.72% were produced and named TG-PH1, TG-PH2 and TG-PH3, respectively. All three TG-modified pepsin hydrolysates exhibited improved solubility at pH between 3.5 and 5.5 as the highest was observed of TG-PH3 at protein isoelectric point (pI=4.5). Sunflower meal protein isolate and TG-modified sunflower meal protein isolate had greater solubility than the three TG-modified hydrolysates at pH<3 and >7. Significant improvement of foam making capacity (p<0.05) was achieved with all three TG-modified pepsin hydrolysates in the entire pH area studied. Pepsin hydrolysis of the protein isolate with the three degrees of hydrolysis did not improve foam stability. Improved thermal stability was observed with TG-PH3 up to 80 °C compared to the protein isolate (pH=7). At 90 °C, TG modification of the protein isolate alone resulted in the highest thermal stability. Pepsin hydrolysis followed by a treatment with TG could be used to produce sunflower protein isolates with improved solubility, foam making capacity and thermal stability for use in the food industry.

Development of protein fortified mango based ready-to-serve beverage

Fruit drinks contain negligible amount of protein as nutritional component. Fortification of fruit drinks with protein is a challenge due to protein stability in acidic and ionic environment. Mango ready-to-serve (RTS) beverage was fortified with modified whey protein and its rheological properties were studied. Whey protein was hydrolysed with papain to improve its stability in acidic medium. The water holding capacity of whey protein increased about two times after hydrolysis. Hydrolysed and native whey protein was used at 2, 3 and 4% levels for fortification of mango based RTS beverage. Addition of hydrolysed whey protein at all the three levels did not significantly change the flow behaviour of the beverage. Native whey protein fortification resulted in precipitation; however, addition of hydrolysed whey protein led to stable beverage formulation at all the three levels. Hydrolysed whey protein imparted slight bitter taste to the RTS beverage, which was masked by β-cyclodextrin @ 0.15% of total protein. The mango RTS beverage with 3.0% hydrolysed whey protein was found acceptable with good sensory appeal and stability during thermal processing as well storage in glass bottles.

Improved Functional Characteristics of Whey Protein Hydrolysates in Food Industry

This review focuses on the enhanced functional characteristics of enzymatic hydrolysates of whey proteins (WPHs) in food applications compared to intact whey proteins (WPs). WPs are applied in foods as whey protein concentrates (WPCs), whey protein isolates (WPIs), and WPHs. WPs are byproducts of cheese production, used in a wide range of food applications due to their nutritional validity, functional activities, and cost effectiveness. Enzymatic hydrolysis yields improved functional and nutritional benefits in contrast to heat denaturation or native applications. WPHs improve solubility over a wide range of pH, create viscosity through water binding, and promote cohesion, adhesion, and elasticity. WPHs form stronger but more flexible edible films than WPC or WPI. WPHs enhance emulsification, bind fat, and facilitate whipping, compared to intact WPs. Extensive hydrolyzed WPHs with proper heat applications are the best emulsifiers and addition of polysaccharides improves the emulsification ability of WPHs. Also, WPHs improve the sensorial properties like color, flavor, and texture but impart a bitter taste in case where extensive hydrolysis (degree of hydrolysis greater than 8%). It is important to consider the type of enzyme, hydrolysis conditions, and WPHs production method based on the nature of food application.

Emulsifying properties of the transglutaminase-treated crosslinked product between peanut protein and fish (Decapterus maruadsi) protein hydrolysates

BACKGROUND

Defatted peanut meal, a protein-rich by-product from the oil extraction industry, is underutilised owing to its inferior functional properties. In this study, transglutaminase (TGase) crosslinking and proteolysis were used to improve the emulsifying properties of peanut protein isolate (PPI) extracted from the meal. PPI and PPI hydrolysate (PPIH) were conjugated separately with fish (Decapterus maruadsi) protein hydrolysate (DPH), catalysed by TGase to obtain improvements in the emulsifying properties.

RESULTS

Analyses by electrophoresis and high-performance liquid chromatography indicated that polymers were formed in all TGase-treated samples. In emulsions of PPIH, PPI-DPH and PPIH-DPH the volume/surface average particle diameter (d(32) ), creaming and instability phenomenon were decreased and the zeta-potential was increased after TGase treatment, showing improved emulsifying activity and emulsion stability. In the case of PPI, TGase treatment had no effect on the emulsifying activity, but the emulsion stability of TGase-treated PPI was improved.

CONCLUSION

The study showed that TGase crosslinking and proteolysis could improve the emulsifying properties of PPI, while proteolysis followed by TGase crosslinking proved more efficient. The emulsifying properties of the heterologous protein systems of PPI-DPH and PPIH-DPH were also improved by TGase treatment.

Conjugation of sodium caseinate and gum arabic catalyzed by transglutaminase

Conjugation of the milk protein sodium caseinate and a protein-containing polysaccharide, gum arabic, was achieved through the use of the cross-linking enzyme transglutaminase. The extent of conjugation was monitored by size exclusion separation coupled with a multiangle laser light scattering detector. The elution times of gum arabic solutions incubated with transglutaminase were unchanged over time, whereas incubation of sodium caseinate with transglutaminase resulted in shorter elution times as reaction time increased, indicating the formation of cross-linked caseinate polymers. However, when mixtures of caseinate and gum arabic were incubated with transglutaminase, the elution times were decreased markedly, indicating conjugation between the protein and polysaccharide. The molecular masses of the conjugates increased from approximately 950 to 1600 kDa. This method of protein-polysaccharide conjugation offers noticeable advantages over previously used methods, and the conjugates produced may exhibit unique functional properties.

Allergenic properties of roasted peanut allergens may be reduced by peroxidase

Peanut allergy is a public health issue. The culprits are the peanut allergens. Reducing the allergenic properties of these allergens or proteins will be beneficial to allergic individuals. In this study, the objective was to determine if peroxidase (POD), which catalyzes protein cross-linking, reduces the allergenic properties of peanut allergens. In the experiments, protein extracts from raw and roasted defatted peanut meals at pH 8 were incubated with and without POD in the presence of hydrogen peroxide at 37 degrees C for 60 min. The POD-treated and untreated samples were then analyzed by SDS-PAGE, western blots, and competitive inhibition ELISA. IgE binding or allergenicity was determined in blots and ELISA. Results showed that POD treatment had no effect on raw peanuts with respect to protein cross-linking. However, a significant decrease was seen in the levels of the major allergens, Ara h 1 and Ara h 2, in roasted peanuts after POD treatment. Also, polymers were formed. Despite this, a reduction in IgE binding was observed. It was concluded that POD induced the cross-linking of mainly Ara h 1 and Ara h 2 from roasted peanuts and that, due to POD treatment, IgE binding was reduced. The finding indicates that POD can help reduce the allergenic properties of roasted peanut allergens.