Effects of non-thermal plasma treating wheat kernel on the physicochemical properties of wheat flour and the quality of fresh wet noodles

The effects of non-thermal plasma (NTP) on the physicochemical properties of wheat flour and the quality of fresh wet noodles ( FWN) were investigated. The results showed that NTP effectively decreased the total plate count (TPC), yeast and mould count (YMC) and Bacillus spp. in wheat flour. Wet gluten contents and the stability time reached the maximum when treated for 20 s. The viscosity of starch increased significantly after treatment due to the increased of damaged starch. The contents of secondary structure were altered to some extent, which was because that the ordered network structure of gluten protein broken. Furthermore, compared with the control, texture properties of FWN were enhanced significantly at 20 s, and the darkening rate of FWN was greatly inhibited due to the low polyphenol oxidase (PPO) activity. Consequently, the most suitable treatment was 500 W for 20 s, providing a basis for the application of NTP in flour products.     

Rapid evaluation of olive oil quality by NIR reflectance spectroscopy

NIR spectroscopy calibrations have been developed for a range of quality parameters in olive oil, including FFA, PV, polyphenol content, induction time, chlorophyll, and the major FA. A set of 216 olive oil samples from throughout the Australian olive-growing areas were used to provide a representative range of quality. The variation in the oils tested virtually covered the range of the chemical standard limits described by the International Olive Oil Council. A FOSS NIRSystems^® 6500 spectrophotometer with a liquid cell holder was used. Multiple correlation coefficients squared (R ²) for minor components stearic acid (0.86), and linolenic acid (0.85) were relatively low because the concentration range is very narrow compared with the reproducibility of the reference method. However, the major FA, oleic (0.99) and linoleic (1.00), FFA (0.97), and chlorophyll (0.98) provided high levels of accuracy. All of the parameters measured were sufficiently accurate for routine screening of olive oil.     

多酚氧化酶催化单宁的氧化聚合反应研究

研究了多酚氧化酶催化单宁的氧化聚合反应情况 ,探索了反应条件及 7种化合物对酶活性的抑制效果 ,对产物进行了红外光谱和紫外光谱测试 ,相对粘度法测定了产物的分子量。结果表明 ,反应的最佳条件是pH为 5 .2 9,温度为 3 0℃ ,在所用抑制剂中 ,硫酸铜的抑制作用最强 ,与单宁酸的IR图相比 ,产物的 -OH吸收带变窄 ,在 12 60cm-1处吸收峰增强 ,而紫外吸收无变化。产物平均分子量为 3 5 41,说明多酚氧化酶能催化单宁的氧化聚合     

大孔吸附树脂纯化石榴皮多酚

从D3520、D4020、AB-8、D140、D141、D160、DM-301、DA-201、SAD-7和D101大孔吸附树脂中筛选出D141树脂,研究了其对石榴皮多酚的静态与动态吸附和解吸性能。结果表明,D141树脂对石榴皮多酚的饱和吸附量为19.86 mg/g(干树脂),吸附等温线符合Langmuir方程,饱和吸附时间为5 h,适宜解吸剂为体积分数70%的乙醇溶液;以质量浓度9 mg/mL的石榴皮提取液上柱,流速为1.8~2.0 BV/h时,树脂的多酚穿透吸附容量为39.42 mg/g(干树脂),2.5 BV体积分数70%的乙醇溶液可将吸附于柱上的石榴皮多酚完全洗脱。以该条件纯化石榴皮多酚提取物时,纯化样的收率为15.4 g/100 g(石榴皮),多酚质量分数从34%提高到76.34%。     

苹果多酚的研究进展

苹果多酚作为一种新型的天然抗氧化剂,是苹果中一类重要的活性物质,在未成熟的苹果和果渣中含量丰富。介绍了苹果多酚的组成及性质、生化及生理功能、制备方法及分析,在医药、功能性食品、化妆品等领域的应用前景,并对苹果多酚的研究现状作了概述。     

黄心甘薯多酚类物质的提取工艺研究

以黄心甘薯粉为原料,研究了有机溶剂浸提法提取甘薯多酚类物质的工艺.通过单因素和正交试验,确定出提取黄心甘薯多酚类物质的最佳工艺条件:提取溶剂为75%乙醇,提取温度为90℃,提取液pH值为6.0,固液比为1∶10,浸提时间为1.0 h,浸提次数为2次.在该优化条件下黄心甘薯多酚类物质含量为6.082 mg/g.方差分析表明,提取液pH值和提取温度对提取率的影响达到了显著水平.     

Antagonism between jasmonate- and salicylate-mediated induced plant resistance: effects of concentration and timing of elicitation on defense-related proteins,herbivore, and pathogen performance in tomato

The jasmonate (JA) and salicylate (SA) signaling pathways in plants provide resistance to herbivorous insects and pathogens. It is known that these pathways interact, sometimes resulting in antagonism between the pathways. We tested how the timing and concentration of elicitation of each pathway influenced the interaction between the jasmonate and salicylate pathways measured in terms of five biochemical responses and biological resistance to caterpillars and bacteria. The salicylate pathway had a stronger effect on the jasmonate pathway than did the reverse. The negative signal interaction was generated by two distinct paths in the plant. A negative interaction in the biochemical expression of the two pathways was most consistent in the simultaneous elicitation experiments compared to when the elicitors were temporally separated by two days. Herbivore bioassays with Spodoptera exigua also consistently reflected an interaction between the two pathways in the simultaneous elicitation experiments. The negative signal interaction reducing biological resistance to the herbivore was also demonstrated in some temporally separated treatment combinations where attenuation of the biochemical response was not evident. Concentration of the elicitors had an effect on the pathway interaction with consistent biochemical and biological antagonism in the high concentration experiments and inconsistent antagonism in the low concentration experiments. The bacterial pathogen, Pseudomonas syringae pv. tomato (Pst), consistently showed reduced lesion development on plants with SA responses activated and, in some experiments, on JA-elicited plants. Resistance to Pst was not reduced or enhanced in dual-elicited plants. Thus, signal interaction is most consistent when elicitors are applied at the same time or when applied at high doses. Signal interaction affected the herbivore S. exigua, but not the pathogen Pst.     

Kinetics of ultrasonic extraction of polyphenols,anthocyanins and tannins from five different New Zealand grape pomaces

Polyphenols were extracted from five kinds of New Zealand grape pomace (Sauvignon Blanc, Pinot Gris, Gerwurztraminer, Merlot and Pinot Noir) at 30, 50 and 70 °C in an ultrasonic generator. The extraction kinetics for total phenol, anthocyanin and tannin were determined. The results of dynamics study showed that the extraction of total polyphenols, anthocyanin and tannin followed first-order reaction kinetics during the extraction at 30, 50 and 70 °C. The total phenolic content, anthocyanin conten, and tannin content of water–ethanol extracts from grape pomaces were compared, and the parameters in the extraction kinetics equations were determined. The extraction results showed that the Pinot Noir pomace extract had the highest total phenolic content of 59.95 mg GAE g⁻¹ pomace and tannin content of 79.93 mg EE g⁻¹ pomace. The anthocyanin content in Merlot pomace extract was the highest, which was 4.50 CE g⁻¹ pomace. The results might be of great significance for the development of grape pomace or its polyphenol and/or anthocyanin components as an antioxidant source with natural and inexpensive benefits.     

Comparison of biochemical properties and thermal inactivation of membrane‐bound polyphenol oxidase from three apple cultivars (Malus domestica Borkh)

A comparative study of the properties of membrane‐bound polyphenol oxidase (mPPO) from three apple cultivars, namely Red Fuji (FJ), Granny Smith (GS) and Golden Delicious (GD), was carried out for the first time. Data indicate that mPPOs from three cultivars exhibit significantly different properties. GS mPPO had the strongest affinity to catechol, but FJ mPPO had the highest maximum velocity. Red Fuji (FJ) mPPO had the significantly higher activity than those of GD and GS mPPOs. Red Fuji (FJ) mPPO had the highest activity at pH 8.00, while GD and GS mPPOs at 4.50 and 7.50–8.00, respectively. Red Fuji (FJ) mPPO was more stable than GD and GS mPPOs over the pH range of 5.0–8.5. The optimal temperature for GS mPPO was within 70–75 °C, which is higher than those for mPPOs from FJ and GD. Thermal inactivation of the three mPPOs followed a first‐order kinetic model with different inactivation kinetic parameters.