Impact of enzymatic hydrolysis followed by transglutaminase-induced cross-linking on decreasing antigenicity and reserving partial interfacial properties of whey protein isolate.

Whey protein isolate (WPI) was hydrolyzed by alcalase and trypsin for three hydrolysis degrees (DHs), followed by transglutaminase (TGase) induced cross-linking. The prepared products were measured for surface hydrophobicity and emulsifying and foaming properties, as well as in vitro antigenicity for α-lactalbumin and ß-lactoglobulin. The results indicated that enzymatic hydrolysis of WPI mostly resulted in WPI hydrolysates with significantly decreased antigenicity of α-lactalbumin and ß-lactoglobulin, especially in the case of a higher DH value. Moreover, the TGase-induced cross-linking led to a further antigenicity decrease for these prepared products. Alcalase was always more potent than trypsin to decrease antigenicity. In comparison with WPI, the conducted enzymatic hydrolysis also brought losses to surface hydrophobicity and emulsifying and foaming properties. On the other hand, the conducted cross-linking could partially rescue these properties. It is thus concluded that the assessed enzymatic hydrolysis coupled with TGase-induced cross-linking might be an applicable process for WPI to decrease its potential antigenicity but reserve partial interfacial properties.

Biodegradation of two organophosphorus pesticides in whole corn silage as affected by the cultured Lactobacillus plantarum.

Biodegradation of the pesticides is considered as one of the safest and cheapest ways. The aim of the present study was to reveal if the inoculated Lactic acid bacteria widely used in silage could provide beneficial safety to guarantee dairy feedstuffs and fresh milk. Organophosphorus pesticides (OPPs) degradation in whole corn silage was investigated. Two OPPs, chlorpyrifos and phorate, were added to the whole corn, which was inoculated with L. plantarum 1.0315, L. plantarum 1.0624, L. plantarum 1.0622 and their combination at room temperature for 10 weeks. OPPs residues in the whole corn silage at different weeks were analyzed by gas chromatography after OPPs extraction and purification. The degradation rate constants were calculated according to the OPPs residues results at different fermentation stage. The data showed that the inoculated microorganisms and strain combination exhibited obvious acceleration on OPPs degradation as the wild microorganisms did, and resulted in decreased levels of OPPs from 24.9 to 33.4 %. Strains combination brought about greater OPPs degradation than single strain or the wild microorganisms. Compared to phorate, clorpyrifos had lower degradation rate constants (0.0274-0.0381 vs. 0.0295-0.0355 week-1) and was more stable. The present result indicates safety benefit of lactic acid bacteria on corn silage besides lactic acid fermentation.