拮抗酵母菌控制水果及其制品中展青霉素研究进展

展青霉素是由部分曲霉、青霉产生的有毒的代谢产物,主要污染水果及其制品,对人、畜危害较大。水果及其制品中展青霉素的常用控制方法是物理方法和化学方法,但物理方法和化学方法都存在一些弊端,限制了其在实际生产上的应用。近年来,采用拮抗酵母菌控制水果及其制品中展青霉素已成为学术研究的热点。本文对拮抗酵母菌控制水果及水果制品中展青霉素的研究进展进行了综述。     

山茱萸果酒主发酵工艺研究

以山茱萸干果肉为原料,经D254高活性干酵母发酵生产山茱萸保健果酒。以保健果酒的酒精度和感官评分为依据,通过单因素试验和正交试验,优选出山茱萸果酒发酵最佳工艺条件为干酵母用量0.7 g/L,发酵温度25 ℃,发酵时间35 d。在此条件下,山茱萸果酒酒精度为（7.8±0.2）%vol,感官评分为（85±4.6）分。优选出的工艺可为山茱萸果酒的大生产提供一定的理论依据。     

HPLC测定刺梨果实中维生素C含量方法的优化

以"贵农5号"刺梨果实为材料,在已有的高效液相色谱(HPLC)测定维生素C(Vc)方法的基础上,对提取液、提取次数、提取液保存温度及色谱条件等方面进行了改进和优化,以期筛选出从这种高含量维生素C果实中提取测定Vc含量的适宜方法。结果表明:6%的偏磷酸较之添加2 mM EDTA、1%pvpp的提取液更适合刺梨果实Vc的提取;二次提取在刺梨果实Vc提取中很有必要;8 h内,刺梨果实Vc提取液适合在4℃保存,如果需过夜保存,应选择-20℃;所选择高效液相色谱法Vc含量在40~400μg/mL(r=0.9997)范围内呈良好的线性关系,平均回收率为101.80%(RSD=1.01%),可用于刺梨果实及其他高Vc含量植物材料Vc的测定。     

Oxidative stability of olive oil during the thermal process: Effect of Pistacia khinjuk fruit oil

The oxidative stability of refined olive oil with incorporated Pistacia khinjuk fruit oil (PKFO; 0.5%, 1%, 2%, 5%, and 10%) during thermal processing at 170ºC for 8 h was evaluated. The conjugated diene values, carbonyl values, acid values, oil/oxidative stability indices, and total tocopherol content were measured during thermal processing. Olive oil containing 0.5% PKFO was identified as the most oxidative stable oil followed by oils containing 100 ppm TBHQ and 1, 5, 10, and 2% PKFO. No significant difference between samples of olive oil containing 100 ppm TBHQ and 1% PKFO was observed. Thus, it was concluded that PKFO at levels lower than 1% could provide stronger antioxidation activity in comparison with TBHQ (the strongest syntactic antioxidant used in the food industry). Moreover, reduction in tocopherol compounds during thermal processing was higher in olive oil containing TBHQ as compared to those in pure olive oil.     

百香果全果与果汁发酵酒滋味成分及香气成分对比

目的：提升百香果酒品质。方法：以百香果全果和果汁为原料酿制百香果酒,分别测定其有机酸、氨基酸和挥发性化合物含量,并结合电子舌试验结果评价百香果酒风味成分。结果：2种百香果发酵酒中主要有机酸为酒石酸、柠檬酸、乳酸和苹果酸,但全果酒的前3种有机酸含量均显著高于果汁酒中的（P<0.05）,全果酒和果汁酒中含量最多的有机酸分别为酒石酸（27.20 mg/mL）和柠檬酸（12.49 mg/mL）;除半胱氨酸未检出外,全果酒和果汁酒中16种游离氨基酸总含量分别为88.16,68.88 mg/100 g,且全果酒中4类呈味氨基酸含量高于果汁酒;电子舌测试发现,2种百香果发酵酒中咸味信号强度差异性最大,且全果酒中的鲜味、咸味最强,酸味、涩味和甜味最弱;HS-SPME-GC-MS共检出179种香气成分,全果酒中挥发性风味化合物种类比果汁酒多4种,但其萜烯类物质含量和种类分别比果汁酒的多1,3倍。结论：相比于果汁酒,新型百香果全果酒整体风味（鲜味、咸味、萜烯类物质等）较突出,提升了百香果资源的综合利用度。     

Survey of South African fruit juices using a fast screening HILIC-MS method

Adulteration of fruit juices – by the addition of sugar or other less expensive fruit juices as well as preservatives, artificial sweeteners and colours – was tested for by using a developed screening method. The method employs hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) using electrospray ionisation in the negative mode and ultraviolet light detection. Different fruit juices can be differentiated by the content of marker compounds like sorbitol, certain phenolic molecules and their saccharide profile. This method was used to test 46 fruit juice samples from the retail market as well as 12 control samples. The study focused on the main types of fruit juices consumed on the South African market including apple, orange, grape and blends of these juices with other fruits like mango, pear and guava. Overall, the 46 samples tested mostly agreed with label claims. One grape juice sample was adulterated, probably with apple juice. Natamycin above the legal limits was found in two samples. In addition, two samples contained natamycin and one sample benzoate without it being indicated on the label. The method is well suited as a quick screening method for fruit juice adulteration and if used routinely would reduce fruit juice adulteration without the cost of the current array of tests needed for authenticity testing.     

Antioxidant Capacity and Phenolic Content of the Aqueous Extract of Commonly Consumed Cucurbits

The antioxidant capacity of commonly consumed cucurbits vegetable was determined by the DPPH, FRAP, Fe³⁺ reducing power, and hydrogen peroxide scavenging assay. The aqueous extract of Luffa cylindrica showed the highest value of phenolic content and antioxidant capacity based on FRAP, Fe³⁺ reducing power, and hydrogen peroxide scavenging assay. However, Laginaria siceraria extract showed the highest flavonoid and DPPH scavenging activities among all three cucurbits used in this study. Phenolic content in aqueous extracts of Luffa cylindrica and Laginaria siceraria was almost equal. Cucurbita maxima exhibited the lowest phenolic, flavonoid content, and exhibited the lowest power of antioxidant scavenging. The antioxidant capacity of cucurbits was significantly correlated (P < 0.05) with the phenolic content of their extracts. The antioxidant capacity of Luffa cylindrica and Laginaria siceraria have also shown a significant correlation (P < 0.05).     

Phenolic composition of Tempranillo wines following early defoliation of the vines

BACKGROUND: Early defoliation is a viticultural practice aimed at crop control. So far, the impact of early leaf removal on the monomeric phenolic composition of wines has not been explored. This study examines the effects of early defoliation on the phenolic profile and content in Tempranillo wines. The influence of the defoliation method (manual vs mechanical) and the timing of leaf removal (pre‐bloom vs fruit set) was investigated. RESULTS: Over two consecutive seasons, 2007 and 2008, the monomeric phenolic composition in Tempranillo wines was studied by high‐performance liquid chromatography with photodiode array detection, and 22 compounds were identified and quantified. Overall, early defoliation led to wines more intensely coloured, of higher alcohol content and with larger concentrations of hydroxycinnamic acids, flavonols and anthocyanins (in 2008 only for mechanical treatments). In the absence of fungal infection, resveratrol was found to increase in wines corresponding to early defoliation treatments. The method of leaf removal seemed to be more critical than the timing of intervention, and larger effects on wine phenolic composition were observed for mechanical treatments. CONCLUSION: Early defoliation proved to be an effective technique for improving the phenolic composition of Tempranillo wines, by favouring the accumulation of hydroxycinnamics, flavonols and anthocyanins. This is an important achievement, as wine quality is often described by its colour and phenolic attributes. Copyright © 2011 Society of Chemical Industry     

温州蜜桔果醋加工工艺优化研究

为开发以温州蜜桔为原料的高品质健康饮品——柑桔果醋,对柑桔果醋的澄清和发酵工艺参数等进行了系统的研究。研究结果表明:20m L/t的4000活力单位的液体果胶酶和0.15%的101澄清剂复合使用,澄清效果明显;最佳发酵工艺条件为:菌种接种量10%,发酵温度32℃,发酵时间72h。     

枸杞芽茶与叶茶的化学成分和抗氧化活性分析

以宁夏枸杞芽茶、枸杞叶茶为原料,利用热水浸提(料液比1∶40、温度96℃、时间30 min)制备枸杞芽茶与叶茶提取物并对其所含的化学成分含量进行测定,采用HPLC对枸杞芽茶与叶茶提取物中游离氨基酸的组成进行了分析,利用DPPH自由基、ABTS自由基、超氧阴离子自由基清除率、总还原力为指标对枸杞芽茶、叶茶茶汤提取物的抗氧化活性进行分析评价。结果表明,枸杞芽茶、枸杞叶茶提取物中多酚含量分别为6.32%、2.96%。枸杞芽茶与叶茶提取物中天冬氨酸(3230.41、2440.96μg/g)、天冬酰胺(3754.77、3495.57μg/g)、组氨酸(5585.26、2825.17μg/g)以及亮氨酸(4376.09、1051.00μg/g)含量较为丰富。枸杞芽茶与叶茶提取物相比抗氧化活性较强,二者对DPPH自由基(IC50:147.63、241.23μg/m L)、ABTS自由基(IC50:109.87、145.32μg/m L)以及超氧阴离子自由基(IC50:46.58、54.32μg/m L)均具有良好的清除能力,与叶茶相比,枸杞芽茶具有更好的抗氧化活性。