Effect of enzymatic hydrolyzed protein from pig bones on some biological and functional properties.

Pig bone residue is considered a potential source of hydrolysates from its protein with added value uses in the food industry. This work deals with the enzyme hydrolysis of pig bone protein. The conditions for extracting the protein hydrolysate were optimized and the equation obtained allowed samples with different degrees of hydrolysis (DH) to be extracted to study how the biological properties of in-vitro hydrolized protein affected digestibility, determination of the inhibitory activity of the angiotensin-converting enzyme and the antioxidant activity and its functional properties. It was found that the emulsifying capacity and emulsion stability increased at intermediate DH values, after which these properties decreased with the increase in DH. The in-vitro digestibility and angiotensin-converting enzyme (ACE) of the hydrolysates are also clearly affected by the DH. The amino acid composition of the hydrolized protein is also determined.

Application of Ultrasound-Ultrafiltration-Assisted alkaline isoelectric precipitation (UUAAIP) technique for producing alfalfa protein isolate for human consumption: Optimization, comparison, physicochemical, and functional properties.

A new Ultrasound-Ultrafiltration-Assisted Alkaline Isoelectric Precipitation (UUAAIP) technique was employed for producing alfalfa protein isolate from alfalfa leaves. A five-factor-three-level Box-Behnken Design (BBD) was used to optimize the UUAAIP process for maximizing both extraction yield and protein content simultaneously. The optimum conditions were as follows: solvent/solid material ratio of 43.3 mL/g, pH of 10.1, extraction temperature of 42.5 °C, extraction time of 102 min, and flow rate of 9.7 L/h. Under these conditions, the maximum predicted extraction yield and protein content were 14.5 g/100 g and 91.1 g/100 g, respectively. UUAAIP technique improved the average molecular weight and color of the isolate. Moreover, it was efficient in removing the saponins and phenolic compounds as anti-nutritional factors compared to heat-coagulation extraction (HCE) and alkaline isoelectric precipitation extraction (AIPE). The protein isolate extracted by UUAAIP had greater solubility, water-holding and oil-binding capacities but lower emulsifying and foaming properties than those extracted by HCE and AIPE.

Optimisation and kinetic study of the ultrasonic-assisted extraction of total saponins from alfalfa (Medicago sativa) and its bioaccessibility using the response surface methodology.

The ultrasonic-assisted extraction of total saponins from alfalfa leaves was optimised by the simultaneous maximization of the yield and bioaccessibility as a factor with increasingly great relevance in the biological activity by Response Surface Methodology. The kinetics of total saponins and bioaccessibility were investigated for the optimum ultrasound-assisted method compared to conventional method by the pseudo-first order model. The optimum extraction conditions were of solvent/raw material ratio of 11.4 mL/g, extraction time of 2.84 h, extraction temperature of 76.8 °C, ultrasound power of 112.0 w and ethanol concentration of 78.2%. The yield of total saponins and bioaccessibility was 1.61 and 18.6%, respectively. The yield rate constant for the ultrasound extraction was almost two times more than that of the heat-reflux method. Ultrasonic-assisted extraction, comparing to conventional method, had greater efficiency for the extraction yield and bioaccessibility of total saponins.

Optimisation of steam blanching on enzymatic activity, color and protein degradation of alfalfa (Medicago sativa) to improve some quality characteristics of its edible protein.

The use of alfalfa protein in human food is limited by its low quality. Response Surface Methodology was employed to optimise the combined effects of different steam blanching conditions on the enzymatic activity, browning and protein degrading which cause undesirable characteristics. The optimum conditions were: steaming time 4.36 min, particle size 23 mm, time from harvesting to steaming 2 h leading to a residual activity of polyphenol oxidase of 1.31% and a completely inactivation of peroxidase. The Browning Index value was 108.3 and the non-protein nitrogen 170.2 (g kg-1 TN). The browning and protein degradation rates of alfalfa treated under the optimum conditions were much lower than the control alfalfa after 60 days ensiling. This suggests that blanching of fresh whole alfalfa leaves under the optimum conditions was helpful for avoiding the appearance of the dark color and degradation of the extracted protein, improving its quality for human consumption.

Albedo hydrolysis modelling and digestion with reused effluents in the enzymatic peeling process of grapefruits.

BACKGROUND: Until now, the optimisation of enzymatic peeling of grapefruit in the reactor has been obtained as the result of the semi-qualitative effects of enzyme activity. This work is an attempt to obtain quantified data. The reuse of enzymes to reduce costs in this process is unprecedented in the literature and is the aim of the present work. RESULTS: The optimal conditions determined for the maximum albedo degradation were a temperature of 40.6 °C and a time of 13.1 min in an enzymatic concentration of 0.067 mL enzymatic preparation per gram of peel in each litre of citrate buffer solution. The decrease in relative enzymatic activities in reused effluents was determined, as was the increase in activity when the enzymes were purified. These increases were 15.5% for polygalacturonase and 15.4% for cellulase activity. CONCLUSION: Optimal temperature, time and the ratio between peel mass and the enzymatic preparation volume were the best conditions for obtaining good peeling efficiency. The effluents from the enzymatic peeling process of the grapefruit still contain appreciable enzymatic activity after the digestion process. Thus, reusing these effluents while maintaining peeling efficacy and a subsequent recovery of the active enzymes by ultra-filtration of the effluents is the way to improve the efficiency of the process.

Toxic effect of melanoidins from glucose-asparagine on trypsin activity.

In this work the effect of the presence of the melanoidins from glucose-asparagine on the enzymatic activity of trypsin is studied. It was observed that an excess of N alpha-benzoyl-L-arginine ethyl ester (BAEE) has an inhibiting effect on this enzyme activity. The maximum reaction rate was obtained for a 0.06 mN substrate concentration. It is also observed that the presence of melanoidin inhibits the enzymatic activity of trypsin. This inhibition can be described as a linear mixed type where the inhibition constant alpha K(i) of the substrate-inhibitor complex is higher than the inhibition constant K(i) of the complex enzyme-inhibitor with a alpha value of 1.88.