Elucidation of colour development and microstructural characteristics of Allium sativum fumigated with acetic acid

It has been well known that the greening of Allium sativum cloves could be formed after immersed in acetic acid solution. Nonetheless, no investigation was reported on colour development of A. sativum in response to acetic acid vapour until now. In this study, the brief exposure of A. sativum to acetic acid vapour (200–400 ppm) was combined with controlled atmosphere (5%, 20% and 80% CO₂) packaging storage to break cell membrane and green garlic. The garlic bulbs were fumigated with acetic acid before controlled CO₂ atmosphere packaging for 25 days at 4 °C. Fumigation with 200 ppm acetic acid followed by high CO₂ atmosphere packaging (80% CO₂) facilitated the garlic greening. It was also verified that γ‐glutamyl transpeptidase was involved in garlic greening in present study, and the compromise of glacial acetic acid vapour fumigation and CO₂ gas atmosphere in package stored at low temperature could result in garlic greening as well.     

Characteristic Anthocyanin Pattern from Onions and other Allium spp

Three red onion (Allium cepa) cultivars, top onion (A. cepa var. vivi-parum), A. altaicum and chive (A. schoenoprasum) contained several or all of the following anthocyanins: 3-(6′-malonyl-3′-glucosylglucoside), 3-(3′,6′-dimalonylglucoside), 3-(6′-malonylglucoside), 3-(3′-malonyl-glucoside), 3-(3′-glucosylglucoside) and 3-glucoside of cyanidin. Trace amounts of two pelargonidin derivatives and the 3,5-diglucosides of cyanidin and peonidin were for the first time reported in red onion. Carbon NMR data showed that the sugars of the 3-(6′-malonyl-3′-glu-cosylglucoside), 3-(6′-malonylglucoside) and 3-glucoside of cyanidin were pyranoses. Substitution either by sugar or acid in the sugar 3-position of an anthocyanin has never been reported outside the genus Allium.     

Effect of coumarin and xanthotoxin on mitochondrial structure,oxygen uptake,and succinate dehydrogenase activity in onion root cells

At concentrations in which they occur on the plant surface and retard mitosis, coumarin and xanthotoxin lowered uptake of oxygen (by 60 and 30%, respectively) by meristematic cells ofAllium cepa root tips. They caused changes in the structure of the mitochondrial matrix to become dense, and protrusions of mitochondrial membranes were visible parallelling their hypertrophy, indicating alteration in the structure and physiology of these organelles. Coumarin and, to a lesser extent, xanthotoxin increased succinate dehydrogenase production in mitochondria and also in the cytoplasm, indicating changes in membrane permeability. Changes in oxygen uptake and mitochondrial structure, in addition to the retardation of mitosis, may be the reason these compounds act as allelochemicals after they have been removed from the plant surface and reach the root meristem.     

沙葱多糖和沙葱黄酮对中式香肠品质的影响

为解决中式香肠亚硝酸盐残留和氧化问题,研究沙葱多糖和沙葱黄酮对中式香肠贮藏过程中(0、2、4、6、8?d)硫代巴比妥酸反应物(thiobarbituric acid reactive substance,TBARs)值、总挥发性盐基氮(total volatile basic nitrogen,TVB-N)含量、保水性...     

乳酸菌复合发酵大蒜风味、活性成分和微生物种群变化分析

本文以大蒜为研究对象,添加植物乳杆菌、嗜酸乳杆菌和鼠李糖乳杆菌等三种乳酸菌发酵大蒜,分析乳酸菌复合发酵大蒜在风味、活性成分和微生物种群变化等方面的特征,为大规模的大蒜发酵生产提供参考。结果显示,发酵30 d后蒜味逐渐消失,并产生香味,口感显著改善;开始发酵后,发酵液p H下降明显,10 d以后发酵液的p H基本保持在4左右;发酵开始后,SOD酶活性有所增加,并保持在250 U的较高水平;细菌群落以添加的三种乳酸菌为主,发酵开始时还伴有肠杆菌、不动杆菌、寡养单胞菌、芽孢杆菌,但发酵后期没检测到肠杆菌、不动杆菌、寡养单胞菌,只检测到三种乳酸菌和芽孢杆菌,而且乳酸菌除了刚发酵时有所降低,其他时间一直保持在较高水平。本文为乳酸复合发酵大蒜的产品开发提供了研究基础。      

沙葱籽油的超临界CO_2萃取及成分分析

以野生沙葱种子为原料,利用超临界CO2流体萃取沙葱籽油。在单因素试验基础上,采用正交试验设计,考察压力、温度、萃取时间、CO2流量4因素对沙葱籽油萃取率的影响。研究得出最佳萃取条件为压力35MPa、温度45℃、萃取时间120min、CO2流量35kg/h,在此条件下油脂萃取率为15.00%。利用GC-MS对沙葱籽油分析,发现沙葱籽油中不饱和脂肪酸主要为亚油酸(63.24%)和油酸(15.99%),占脂肪酸总量的86.65%;饱和脂肪酸以棕榈酸(7.93%)为主,占脂肪酸总量的13.35%。用常规方法对沙葱籽油的理化性质进行测定,结果表明超临界CO2流体萃取法得到的沙葱籽油各项理化指标均良好,产物纯度高、品质好。     

大蒜多糖提取液的澄清条件研究

为了获得澄清透明的大蒜多糖提取液用以生产大蒜多糖,采用不同的pH、不同的澄清剂及其用量等条件处理大蒜多糖提取液。结果表明:在pH为4的条件下,澄清时单宁和明胶用量为0.04%和0.02%,或膨润土、明胶和明矾用量比为0.1%0∶.01%0∶.015%2种方法,均获得了澄清透明的大蒜多糖溶液。该结果可用于大蒜多糖的工业化生产。     

韭菜中农药腐霉利残留的膳食暴露风险评估

目的评估上海市市售韭菜中农药腐霉利的残留情况及居民膳食暴露风险。方法通过2016～2018年间市售韭菜中腐霉利残留的监测数据,结合本市居民食物消费量调查结果,基于蒙特卡罗分析法,采用@Risk7.5软件和风险商值(%ADI)进行风险评估。结果根据GB 2763-2016《食品安全国家标准食品中农药最大残留限量》进行判定,近3年市售韭菜中腐霉利超标率为23.2%,残留量均值和95%分位值(P_(95))分别为0.76 mg/kg和4.81 mg/kg。本市居民通过韭菜腐霉利暴露量均值为6.17×10~(-5) mg·(kg·bw)~(-1)·d~(-1),风险商为0.06%ADI;高端暴露量(P_(95))为1.68×10~(-3)mg·(kg·bw)~(-1)·d~(-1),风险商为1.68%ADI。本市全人群居民通过韭菜、番茄、茄子等8种食用农产品摄入的腐霉利暴露量均值为8.44×10~(-5) mg·(kg·bw)~(-1)·d~(-1)。结论近3年来上海市市售韭菜中腐霉利残留检出率和超标率呈现下降趋势,食品安全监管工作取得一定成效。本市居民通过韭菜摄入腐霉利的风险商值很小,健康风险不大。