Properties of Peanut (KAC431) Protein Hydrolysates and Their Impact on the Quality of Gluten-Free Rice Bread

Protein hydrolysates (PH) with a degree of hydrolysis (DH) of 5%, 10%, and 13% from two varieties of peanut were prepared using two commercial enzymes, Alcalase and Flavourzyme. The content of essential amino acids (30,290 mg/100 g) and hydrophobic amino acids (34,067 mg/100 g) of the peanut variety Kalasin 2 (KAC431) protein was higher than that of a common variety, Kalasin 1 (KAC1) (p < 0.05). The protein molecular weight distributions of the two varieties of peanut detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were similar, ranging from 15 to 75 kDa, with a major protein band at 50–75 kDa. The antioxidant and functional properties of derived PHs were influenced by DH. Although the foaming ability of protein was improved by DH5%, it was obviously decreased upon increasing DH further. The best emulsifying properties were observed in PH with DH5% (p < 0.05). The incorporation of PH with a small DH, especially when produced using Flavourzyme, had a highly positive impact on the specific volume and relative elasticity of gluten-free bread. The effect of PHs on bread quality was highly correlated with their functional properties. This study suggests that partially enzymatically modified proteins are suitable for incorporation in food products such as bread and other gluten-free products.

Effect of red Jasmine rice replacement on rice flour properties and noodle qualities

This study aimed to assess flour and noodle qualities after substituting Phitsanulok rice flour (PH) with red Jasmine rice flour (RJ). Blended rice flours were prepared by replacing PH with RJ at various ratios [100:00 (0RJ), 75:25 (25RJ), 50:50 (50RJ), 25:75 (75RJ), and 00:100 (100RJ)]. Some quality improvements were observed in the blended rice flour in terms of chemical and pasting properties at the replacement ratio of 75:25 (p < 0.05). At the same ratio, total phenolic contents, antioxidance activites, and some textural and sensory properties of noodle were developed (p < 0.05). However, increasing values of some undesirable properties including cooking loss and rehydration were also observed (p < 0.05). The noodle made from 100RJ showed the highest level of acceptability but not significantly different compared with others (p > 0.05). Thus, RJ could be used to improve the nutritional value of rice flour, and it could be used for development of health benefits in rice noodle.

Effects of plasticizers on the properties of fish myofibrillar protein film

This study investigated the effects of various plasticizer types [glycerol (GLY), sorbitol (SOR), and polyethylene glycol (PEG)] on the properties of fish myofibrillar protein (FMP) film. FMP films plasticized with GLY showed the greatest elongation at break (116.53%). It also showed the greatest water vapor permeability (1.43 × 10-10 g m-1 s-1 Pa-1). The film plasticized with SOR exhibited the highest tensile strength (12.56 MPa) and film solubility (62.59%). PEG plasticized film showed to have yellowish colour as indicated by the high b* value and low light transmission at 280 nm. Furthermore, FMP films containing PEG and SOR possessed lower moisture content than films with GLY. FT-IR and electrophoretic properties were not affected by any types of plasticizer. The appearance of the FMP film was similar to that of the PVC film. It was concluded that plasticizers had major effects on FMP films. They not only plasticize the protein film, but also affected other major film properties.

Fractionation and antioxidant properties of rice bran protein hydrolysates stimulated by in vitro gastrointestinal digestion

Rice bran was used as a starting material to prepare protein concentrate through enzyme-assisted extraction. The hydrolysis of protein concentrate under in vitro gastrointestinal digestion (pepsin-trypsin system) greatly improved the antioxidant properties. Rice bran protein hydrolysate was further fractionated by membrane ultrafiltration (UF, F1: molecular weight (MW) <3kDa, F2: MW 3-5kDa, and F3: MW 5-10kDa). Peptides with smaller MW possessed higher antioxidant activities (P<0.05). UF showed a great efficacy to selectively separate the metal-chelating peptides. Tyrosine and phenylalanine had positive correlations with their DPPH & ABTS radicals scavenging activities and ferric reducing antioxidant power (r>0.831). A major peptide fragment was detected at m/z 1088 by a MALDI-TOF mass spectrometry. There is high potential that antioxidative peptides from rice bran might also be produced in the gastrointestinal tract of the human body.

Effect of protein concentrations on the properties of fish myofibrillar protein based film compared with PVC film

The effect of protein concentrations on the properties of fish myofibrillar protein film (FMP) were investigated and compared with commercial wrap film (polyvinyl chloride; PVC). FMP (2 %, w/v) showed the highest mechanical properties [tensile strength: 4.38 MPa and elongation at break: 133.05 %], and water vapor permeability [2.81 × 10(-10) g m(-1) s(-1) Pa(-1)]. FMP contained high molecular weight cross-links, resulting in complex film network, as indicated by lower film solubility (19-22 %) and protein solubility (0.6-1.3 %). FMP showed excellent barrier properties to UV light at the wavelength of 200-280 nm. FMP had the thickness [0.007-0.032 mm], color attributes and transparency similar to PVC film [thickness: 0.010 mm]. Therefore, protein concentration majority influenced the properties of develop FMP. The protein content of 1 % (w/v) had potential to be developed the biodegradable film with comparable properties to the commercial wrap film.

Enhanced recovery of alkaline protease from fish viscera by phase partitioning and its application

Background

Too many different protein and enzyme purification techniques have been reported, especially, chromatographic techniques. Apart from low recovery, these multi-step methods are complicated, time consuming, high operating cost. So, alternative beneficially methods are still required. Since, the outstanding advantages of aqueous two phase system (ATPS) such as simple, low cost, high recovery and scalable, ATPS have been used to purify various enzymes. To improve purification efficiency, parameters affected to enzyme recovery or purity was investigated. The objectives of the present study were to optimize of alkaline protease recovery from giant catfish fish viscera by using ATPS and to study of hydrolytic patterns against gelatin.

Results

Using 70% (w/w) crude enzyme extract (CE) in system (15% PEG2000-15% sodium citrate) provided the highest recovery, PF and K_E. At unmodified pH (8.5) gave the best recovery and PF with compare to other pHs of the system. The addition of 1% (w/w) NaCl showed the recovery (64.18%), 3.33-fold and 15.09 of K_E compared to the system without NaCl. After addition of 10% (w/w) sodium citrate in the second ATPS cycle, the highest protease recovery (365.53%) and PF (11.60-fold) were obtained. Thus, the top phase from the system was subjected to further studied. The protein bands with molecular weights (MWs) of 20, 24, 27, 36, 94 and 130 kDa appeared on the protein stained gel and also exhibited clear zone on casein-substrate gel electrophoresis. The β, α₁, α₂ of skin gelatin extensively degraded into small molecules when treated with 10 units of the extracted alkaline protease compared to those of the level of 0.21 units of Flavourzyme.

Conclusions

Repetitive ATPS is the alternative strategy to increase both recovery and purity of the alkaline protease from farmed giant catfish viscera. Extracted alkaline protease exposed very high effectiveness in gelatin hydrolysis. It is suggested that the alkaline protease from this fish viscera can further be used in protein hydrolysate production.