Aishwarya Mohan

Encapsulation of food protein hydrolysates and peptides: a review

Food protein hydrolysates and peptides are considered a category of promising functional food ingredients. However, commercial application of protein hydrolysates and their constituent peptides can be impeded by their low bioavailability, bitter taste, hygroscopicity and likelihood of interacting with the food matrix. Encapsulation as a delivery mechanism can be used to overcome these challenges for improving the bioavailability and organoleptic properties of the peptides. Proteins, polysaccharides and lipids are the three carrier systems that have been utilized in food peptide encapsulation. The protein and polysaccharide systems mainly aim at masking the bitter taste and reducing the hygroscopicity of protein hydrolysates, whereas the lipid-based systems are intended for use in enhancing the bioavailability and biostability of encapsulated peptides. A spray drying technique is largely used to achieve microencapsulation in both protein and polysaccharide systems while, generally, liposomes are prepared by a film hydration technique. However, it is seen that the encapsulation efficiency (EE) of peptides using the liposome model is relatively lower since the entropy-driven liposome formation is uncontrolled and spontaneous. Achieving adequate EE through cost effective techniques is indispensable for encapsulation to be applicable to bioactive peptide-based product commercialization. Furthermore, the design of high quality functional foods requires detailed understanding of the release mechanism and kinetics, gastrointestinal stability, bioavailability and physiological bioactivity of the encapsulated peptide products.

Modification of peptide functionality during enzymatic hydrolysis of whey proteins

Peptides derived from food proteins have shown promise as active ingredients for functional food formulation. Due to their reactivity, we evaluated the effects of conditions used for enzymatic hydrolysis of whey protein isolate (WPI) on the functionality of the resulting peptides. Free amino contents were increased when papain and alcalase were used for WPI hydrolysis, but the proteins (especially β-lactoglobulin) were mostly resistant to pepsin activity. The release of peptides during WPI hydrolysis was associated with increase in ferric reducing capacity, but there were also notable decreases in the redox-active sulfhydryl (SH) groups in the papain and alcalase reactions. Apparently, the reducing capacity of the hydrolysates was not dependent on their SH contents, which could have been utilised in disulfide formation. Moreover, considering that the WPI contained 1% lactose and other sugars, we observed that intermediate and advanced Maillard reaction products (MRPs) were formed during WPI hydrolysis, and this can directly impact both the reducing capacity and SH content of peptides. MRPs, such as reductones, can be highly antioxidative and possibly contributed to the reducing capacity observed for the protein hydrolysates, even with the depletion of the SH moieties. A model Maillard reaction with arginine, lactose or glucose, and reduced glutathione was used to confirm SH depletion in the presence of MRPs, and this was attributed to a nucleophilic reaction with carbonyl derivatives generated during the non-enzymatic glycation reaction. Although this can be an opportunity for generating strong redox-active ingredients, it presents some challenges particularly when the native structure of the peptides needs to be conserved for particular biological properties.

Encapsulation of bioactive whey peptides in soy lecithin-derived nanoliposomes: Influence of peptide molecular weight

Encapsulation of peptides can be used to enhance their stability, delivery and bioavailability. This study focused on the effect of the molecular weight range of whey peptides on their encapsulation within soy lecithin-derived nanoliposomes. Peptide molecular weight did not have a major impact on encapsulation efficiency or liposome size. However, it influenced peptide distribution amongst the surface, core, and bilayer regions of the liposomes, as determined by electrical charge (ζ-potential) and FTIR analysis. The liposome ζ-potential depended on peptide molecular weight, suggesting that the peptide charged groups were in different locations relative to the liposome surfaces. FTIR analysis indicated that the least hydrophobic peptide fractions interacted more strongly with choline on the liposome surfaces. The results suggested that the peptides were unequally distributed within the liposomes, even at the same encapsulation efficiency. These findings are important for designing delivery systems for commercial production of encapsulated peptides with improved functional attributes.

Mechanisms of plastein formation, and prospective food and nutraceutical applications of the peptide aggregates ☆

Highlights • Plastein is a gel-like product of protease-induced peptide aggregation.• Plastein is formed by peptide condensation, transpeptidation and physical interaction.• Plastein can be used in enhancing protein quality and debittering protein hydrolysates.• The peptide aggregate also possesses bioactivity related to health promotion.• Future directions toward industrial applications of plastein are suggested.

Microwave irradiation effects on vermicasts potency, and plant growth and antioxidant activity in seedlings of Chinese cabbage (Brassica rapa subsp. pekinensis)

Abstract Vermicasts is rich in beneficial microorganisms and plant growth factors. Unlike soils, the effect of microwave irradiation (MWI) on vermicasts potency has not been reported. This study investigated MWI effects on vermicasts potency, plant growth and biochemical activity in Chinese cabbage ‘Bilko’ seedlings. Fresh, moist vermicasts were microwaved at power output levels: 0, 100, 200, 300, 400 and 800 Watts (W). Water loss, nutrients and total aerobic plate content were assessed. A complete randomized design greenhouse experiment was used to evaluate seedlings growth performance and tissue bioactivity. Water loss increased from 5 mg/g (0 W) to 215 mg/g (800 W). Total dissolved solids and electrical conductivity of the vermicasts gradually increased with an increase in MWI power output level from 0 to 200 W. This was followed by a steep rise through treatment 300 W and a peak at 400 W. Total nitrogen and nitrate decreased, while ammonia-nitrogen and nitrite-nitrogen increased at higher power levels. Similarly, phosphorus, potassium, magnesium, calcium, manganese, barium and molybdenum contents increased while sodium and barium remained fairly constant. However, MWI irradiation reduced total aerobic plate count by ≥50%. Plant growth and biomass were increased by the 400 W and 800 W MWI treatments. Antioxidant activity was highest in 200, 400 and 800 W treated plants. Collectively the finding indicated that the 400 W treatment increased the bioavailability of nutrients, and represents the best option for plant growth enhancement and improved antioxidant activity.