Effect of extrusion variables on antioxidant activity,total phenolic content and dietary fibre content of gluten‐free extrudate from germinated Chenopodium (Chenopodium album) flour

A Box‐Behnken design was used to study the effects of feed moisture content (18–20%), barrel temperature (115–135 °C) and screw speed (225–275 rpm) on the responses; antioxidant activity, total phenolics, dietary fibre, colour (L‐value), hardness, expansion ratio, water absorption index and overall acceptability for development of gluten‐free extrudate based on germinated Chenopodium album flour. Second‐order polynomial fitted model showed that temperature most significantly (P ≤ 0.05) affected the antioxidant activity (AoxA), total phenolics (TPC), expansion ratio, hardness and overall acceptability (OA). Antioxidant activity, total phenolic content and dietary fibre of extrudate varied from 11.56 to 15.93%, 56.77 to 81.28 mg/100 g and 18.65 to 22.06 g/100 g, whereas the lightness and hardness of extrudates ranged from 64.02 to 68.35 and 12.26 to 19.49 N, respectively. The results of this study validate the production of functional and acceptable snack product made from C.  album flour by extrusion cooking.     

Heat treatments of peptides from oyster (Crassostrea gigas) and the impact on their digestibility and angiotensin I converting enzyme inhibitory activity

Food Science and Biotechnology - The changes of protein digestibility, the peptides in the digestive juice and angiotensin I converting enzyme (ACE) inhibitory activity after heating of oysters...     

鲑鱼皮明胶水解物的抗氧化活性及其对细胞氧化损伤的保护作用

采用碱性蛋白酶、木瓜蛋白酶和中性蛋白酶水解鲑鱼皮明胶,得到水解度为4.7%到13.5%的7个明胶水解物,分别评价明胶水解物对自由基的清除能力。明胶水解物(0.5、1、2mg/mL)预先作用BRL大鼠肝细胞2h后,通过H2O2(5mmol/L)诱导氧化损伤,分别测定细胞存活率、乳酸脱氢酶(LDH)、丙二醛(MDA)和谷胱甘肽(GSH)等细胞内抗氧化产物的含量变化。结果表明,明胶水解物的抗氧化活性随着水解度的增大呈增强趋势。明胶水解物对细胞具有保护作用,可显著提高细胞存活率,降低LDH渗出量和MDA生成量,且存在一定的剂量关系,但细胞中GSH含量变化不显著;7个明胶水解物对H2O2诱导肝细胞损伤保护时,细胞存活率与水解物的体外抗氧化活性大小显著正相关,而LDH渗出量和MDA生成量与水解物的体外抗氧化活性大小负相关。      

Effects of polysaccharides and polyphenolics fractions of Zijuan tea (Camellia sinensis var. kitamura) on α‐glucosidase activity and blood glucose level and glucose tolerance of hyperglycaemic mice

The effects of polysaccharides, theaflavins, thearubigins and theabrownin fractions of Zijuan tea on α‐glucosidase and blood glucose level and intolerance of hyperglycaemic mice were evaluated. The polysaccharides or theaflavins fraction exhibited greater inhibition rate of α‐glucosidase than acarbose positive control, thearubigins fraction or theabrownin fraction. The four fractions were delivered to the treatment mice through oval gavage each day for 15 days. The mice in polysaccharides and theaflavins high‐ and low‐dose and theabrownin high‐dose treatments significantly lowered their blood glucose levels while all the treatment mice gained body weight. The mice in polysaccharides, theaflavins and theabrownin high‐ and low‐dose treatments had greater glucose tolerance as well. Thus, the theaflavins and polysaccharides fractions of Zijuan tea effectively moderated the complications of hyperglycaemic mice. The lower effectiveness of thearubigins and theabrownin fractions may be caused by the highly polymerised polyphenolics which decreased their accessibility to α‐glucosidase and digestibility in mice.     

The influence of modified atmospheres and their interaction with water activity on the radial growth and fumonisin B(1) production of Fusarium verticillioides and F. proliferatum on corn. Part II: The effect of initial headspace oxygen concentration

This paper is the second in a series of two that describe the effect of modified atmospheres on the growth and mycotoxin production of Fusarium verticillioides and Fusarium proliferatum on corn. In this part, the effect of initial headspace (IH) oxygen concentration and its interaction with water activity (a(w)) on growth and fumonisin B(1) production was investigated. In addition, the impact of vacuum packaging and in-cooperation of O(2) scrubbing sachets was also studied. It was observed that at all a(w) values studied, reduction of IH O(2) concentration from 20 to 2% had no significant effect on the colony growth rate (g, mm d(-1)) and lag phase duration (lambda, d). However, g and lambda were positively and negatively correlated to a(w). The IH O(2) concentration was determined to have a a(w) dependent effect on the oxygen consumption rate. Although the maximum colony diameter (D(max), mm) decreased with the reduction of the IH O(2) level, the greatest mycelial density occurred at 10% IH O(2) for both isolates. This observation was accompanied by a trend of a decrease in the value of the IH O(2) level at which the most fumonisin B(1) was produced from 15 to 5% when the a(w) was decreased from 0.976 to 0.930 for F. verticillioides. For F. proliferatum the optimum conditions for fumonisin B(1) production shifted from 20% at a(w) 0.976 to 10% at both 0.951 and 0.930. Vacuum packaging and the in-cooperation of O(2) absorbing sachets completely inhibited the growth of both isolates. These results together with those reported in Part I of the study indicate that O(2) should preferably be completely excluded from modified atmospheres that are employed to protect stored corn from fungal growth and mycotoxin production.     

The influence of modified atmospheres and their interaction with water activity on the radial growth and fumonisin B(1) production of Fusarium verticillioides and F. proliferatum on corn. Part I: the effect of initial headspace carbon dioxide concentration

The effect of modified atmospheres on the growth and fumonisin B(1) production of Fusarium verticillioides and Fusarium proliferatum on corn is presented in a series of two papers. In this, the first part, the effect of initial headspace (IH) carbon dioxide concentration and its interaction with water activity (a(w)) on growth and fumonisin B(1) production was evaluated. It was observed that at all a(w) values studied, increase in the IH CO(2) concentration generally resulted in a decrease in the colony growth rate (g, mm day(-1)) and maximum colony diameter (D(max), mm) and an increase in the lag phase duration (lambda, day). Although both a(w) and IH CO(2) concentration had significant and synergistic effects on g, a(w) had the largest effect. As little as 10% IH CO(2) completely inhibited the production of fumonisin B(1) by F. verticillioides. F. proliferatum was more resistant and required 40, 30 and 10% IH CO(2) at a(w) 0.984, 0.951 and 0.930, respectively, to completely inhibit fumonisin B(1) production. These results demonstrate that modified atmospheres containing high CO(2) levels could potentially be employed for the protection of corn from fungal spoilage and mycotoxin contamination during the post-harvest period.     

The cytotoxic effect of Bowman–Birk isoinhibitors,IBB1 and IBBD2, from soybean (Glycine max) on HT29 human colorectal cancer cells is related to their intrinsic ability to inhibit serine proteases

Bowman–Birk inhibitors (BBI) from soybean and related proteins are naturally occurring protease inhibitors with potential health‐promoting properties within the gastrointestinal tract. In this work, we have investigated the effects of soybean BBI proteins on HT29 colon adenocarcinoma cells, compared with non‐malignant colonic fibroblast CCD‐18Co cells. Two major soybean isoinhibitors, IBB1 and IBBD2, showing considerable amino acid sequence divergence within their inhibitory domains, were purified in order to examine their functional properties, including their individual effects on the proliferation of HT29 colon cancer cells. IBB1 inhibited both trypsin and chymotrypsin whereas IBBD2 inhibited trypsin only. Despite showing significant differences in their enzyme inhibitory properties, the median inhibitory concentration values determined for IBB1 and IBBD2 on HT29 cell growth were not significantly different (39.9±2.3 and 48.3±3.5 μM, respectively). The cell cycle distribution pattern of HT29 colon cancer cells was affected by BBI treatment in a dose‐dependent manner, with cells becoming blocked in the G0–G1 phase. Chemically inactive soybean BBI had a weak but non‐significant effect on the proliferation of HT29 cells. The anti‐proliferative properties of BBI isoinhibitors from soybean reveal that both trypsin‐ and chymotrypsin‐like proteases involved in carcinogenesis should be considered as potential targets of BBI‐like proteins.