Comparative effects of pectin and hydrolyzed pectin coating as pre-frying treatments on acrylamide formation in potato chips.

This study aimed to compare the effects of pectin and hydrolyzed pectin coating as pre-frying treatments on acrylamide content and quality characteristics of fried potato chips. The hydrolyzed pectin with molecular weight (Mw) of 8.81 ± 0.49 kDa was obtained through partial degradation of pectin (Mw: 747.57 ± 6.73 kDa) using pectinase. Results showed that both pectin and hydrolyzed pectin coating significantly inhibited acrylamide formation and inhibition rates exceeded 90 %. Hydrolyzed pectin had stronger inhibitory activity against acrylamide formation than pectin, especially when the concentration of hydrolyzed pectin was >2 %, its inhibitory rate exceeded 95 %. Compared to pectin coating, hydrolyzed pectin coating endow fried potato chips with smaller browning, higher crispness, less moisture but higher oil content. Overall, hydrolyzed pectin had better application prospects than pectin in inhibiting acrylamide formation of fried potato chips.

Galactooligosaccharides in infant formulas: Maillard reaction characteristics and influence on formation of advanced glycation end products.

As prebiotics supplemented in infant formulas (IFs), galactooligosaccharides (GOSs) also have many other biological activities; however, their Maillard reaction characteristics are still unclear. We investigated the Maillard reactivity of GOSs and their effects on advanced glycation end product (AGE) formation during IF processing. The results showed that AGE and HMF formation was temperature-dependent and reached the maximum at pH 9.0 in the Maillard reaction system of GOSs and Nα-acetyl-L-lysine. Acidic conditions accelerated HMF formation; however, protein cross-linking was more likely to occur under alkaline conditions. The degree of polymerization (DP) of GOSs had no significant effect on AGEs formation (except pyrraline); however, the greater the DP, the higher the concentration of HMF and pyrraline. Besides, compared with arginine and casein, lysine and whey protein were more prone to Maillard reaction with GOSs. GOSs promoted AGEs formation in a dose-dependent manner during the processing of IFs. These results provide a reliable theoretical basis for application of GOSs in IFs.

Injectable PAMAM/ODex double-crosslinked hydrogels with high mechanical strength.

In situ injectable double-crosslinked hydrogels containing thiol functionalized poly(amido-amine) dendrimers (Gn-PAMAM-NH2-X) and oxidized dextrans (ODex) were prepared under physiological conditions without using potentially cytotoxic cross-linkers. The double-crosslinked structure was created by Schiff's base reaction and the formation of disulfide bonds. The morphology of the hydrogels was characterized by scanning electron microscopy. The gelation time, swelling and rheological behaviors of the hydrogels were investigated. We also studied the adhesive strength and cytocompatibility of the hydrogels. The surface amino density, concentration and generation of PAMAM are the main factors affecting the gelation. Relatively high surface amino density contributes to quick gelation, whereas too great a surface amino may lead to the brittleness of the hydrogel. A moderate concentration of PAMAM (10% wt) is suitable for gelation considering its appropriate gelation time. Where surface amino density and the mass concentration of PAMAM-NH2 were identical, PAMAM with less generation was prone to gelation. The injectable PAMAM/ODex hydrogels have double-crosslinked structures and a high crosslinking density which lead to their high storage modulus. The adhesive strength of the hydrogels is about 2.4 times of commercial available fibrin glue and these hydrogels are nontoxic to L929 mouse fibroblast cells. The L929 cells can attach easily to the surface of hydrogels and proliferate on them, which demonstrates these novel injectable hydrogels are biocompatible and have potential uses in tissue engineering.

Quantitative study of viable Vibrio parahaemolyticus cells in raw seafood using propidium monoazide in combination with quantitative PCR.

In this study we developed a specific and sensitive quantitative PCR (qPCR) method combined with a propidium monoazide (PMA) sample treatment to quantify tdh-positive viable cells of V. parahaemolyticus in raw seafood (PMA-qPCR). The high selectivity of primers and probes were demonstrated by using purified DNA from 57 strains belonging to 18 species. Using these primers and probes for qPCR and in artificial contamination samples, a good correlation was obtained between Ct values and log CFU/reaction in the range of 12-1.2×10(6)CFU/reaction both from qPCR and PMA-qPCR with R(2) values of 0.9973 and 0.9919, respectively. The optimization of PMA concentration showed that 8 µg/mL was considered optimal to achieve a compromise between minimal impact on intact cells and maximal signal reduction in compromised cells. However, turbidity and cell concentration experiments showed that PMA treatment was not effective in samples where turbidities were ≥10 NTU and OD(600 nm) values were ≥0.8. PMA-qPCR was compared with culture isolation and traditional qPCR in environmental samples (including oyster, scallop, shrimp, and crab). The PMA-qPCR resulted in lower numbers of log CFUg(-1) than qPCR, with values having better agreement with numbers determined by culture isolation. In conclusion, this method is an effective tool for producing reliable quantitative data on viable V. parahaemolyticus in raw seafood.