国内外脱水蔬菜、冻干果蔬概述及风险评估分析

通过对世界各国脱水蔬菜、冻干果蔬限制使用的农药残留量、致病菌、主要重金属汞、砷、铅、镉等理化指标和微生物指标的对比与分析,总结出我国现行脱水蔬菜、冻干果蔬生产、加工和检验过程中存在的缺陷;对企业标准、种植品种、产品预检,脱水蔬菜和冻干果蔬安全生产加工技术文件提出有关建议,以提高产品竞争力,促进企业经济效益和社会效益的增长。     

Effect of the inclusion of whole citrus in the ration of lactating ewes on the properties of milk and cheese characteristics during ripening

The effect of including citrus fruits (CF) in the rations of dairy ewes on the milk characteristics and biochemical changes of cheeses during ripening was evaluated. For this purpose, 48 lactating ewes (Guirra breed) were divided into 4 homogeneous groups and fed with isoenergetic and isoprotein rations containing CF at 0, 10, 20, and 30% on a dry matter basis in substitution of dry barley and pelleted beet pulp. During the experimental period, 3 batches of bulk milk were collected from each group and semi-hard cheeses were manufactured. Cheeses were sampled at 15, 30, and 60 d of ripening. Milk coagulation parameters and cheese yield were not negatively affected by the inclusion of CF in the ration. Physicochemical composition of cheeses at 60 d showed statistical differences for lower total solids and fat content of 30% CF cheeses. Proteolysis of cheeses measured by water-soluble nitrogen and total free amino acids content was not influenced by the ration. Differences between rations with respect to free fatty acids were significant for medium- and long-chain free fatty acids, and therefore for total content, but differences did not show a trend related to the increase of CF in the diet. The inclusion of CF in the ration of lactating ewes up to levels of 30% did not negatively affect the properties of milk and the biochemical and sensory characteristics of cheeses.     

Improving the Quality of Fresh-Cut Apples, Pears, and Melons Using Natural Additives

ABSTRACT:  Improving the quality of different fresh-cut fruits by adding natural substances was studied. "Fuji" apples, "Flor de Invierno" pears, and "Piel de Sapo" melons were treated with calcium lactate, N -acetyl-L-cysteine, glutathione, and malic acid and stored for 4 wk at 4 °C. Instrumental texture (penetration), microstructure (light microscopy), acidity, soluble solids, color, pectinmethylesterase activity, and microflora were studied. The results showed that the combined treatment reinforced the cell walls strengthening the structure and texture of these fruits and maintained the L * and a * values throughout 4 wk of storage at 4° C. The combination of additives provided low microbial counts in apples until the 4th week and in melons until the 2nd week. So, this combined treatment could be used to extend the shelf life of some fresh-cut fruits while preserving their quality.     

Active and passive stabilization of body pitch in insect flight

Flying insects have evolved sophisticated sensory–motor systems, and here we argue that such systems are used to keep upright against intrinsic flight instabilities. We describe a theory that predicts the instability growth rate in body pitch from flapping-wing aerodynamics and reveals two ways of achieving balanced flight: active control with sufficiently rapid reactions and passive stabilization with high body drag. By glueing magnets to fruit flies and perturbing their flight using magnetic impulses, we show that these insects employ active control that is indeed fast relative to the instability. Moreover, we find that fruit flies with their control sensors disabled can keep upright if high-drag fibres are also attached to their bodies, an observation consistent with our prediction for the passive stability condition. Finally, we extend this framework to unify the control strategies used by hovering animals and also furnish criteria for achieving pitch stability in flapping-wing robots.     

奇异果芦荟悬浮饮料的研制

研究了以奇异果和芦荟为主要原料的新型复合悬浮饮料的制作工艺,对加工过程中稳定剂的选择进行了探讨,并运用正交试验确定了产品的最佳配方和生产工艺,研制出风味良好的复合悬浮饮料。     

基于乙醇含量的杨梅果实腐烂指数预测模型研究

研究基于乙醇含量的杨梅果实腐烂指数预测模型,以期预测杨梅物流过程中果实腐烂状况。将杨梅果实贮藏于不同温度(0、5、10、15℃和20℃)下,测定其腐烂指数和乙醇含量变化。基于描述微生物生长的Gompertz方程和Arrhenius动力学方程建立杨梅果实腐烂指数变化动力学模型;根据果实腐烂指数和乙醇含量变化的关系,建立基于乙醇含量的果实腐烂指数模型。通过以上两模型建立杨梅果实腐烂指数的预测模型。杨梅果实腐烂指数变化动力学模型和基于乙醇含量的果实腐烂指数模型预测的相对误差分别为2.69%和0.74%,预测精度较高,以此为基础建立的基于果实乙醇含量的腐烂指数预测模型可以较好的预测在0～20℃贮藏杨梅果实的腐烂状况,为实现杨梅果实的无损检测提供理论支持。     

四种采后熏蒸处理对‘安哥诺’李果实贮藏效果影响的多变量分析

利用多变量分析方法探讨4种采后熏蒸处理对李果实品质及抗氧化活性的影响。单因素方差分析的结果表明,二氧化氯显著降低18d贮藏期后李果实腐烂率、总酚、总黄酮、总抗氧化能力以及清除超氧阴离子自由基和DPPH自由基能力,相比而言,1-甲基环丙烯(1-MCP)显著提高李果实花青素、总酚与总黄酮含量,百里酚与乙醇则提高果肉a*值、色度角及色泽比;相关性分析的结果表明,李果实总酚、总黄酮含量与总抗氧化能力、清除超氧阴离子自由基、DPPH自由基和羟自由基能力之间均表现出极显著的相关性效应;偏最小二乘与通径分析表明,腐烂率与果肉a*值呈现正相关性效应,果肉色度角与清除羟自由基能力存在正相关关系。     

武隆猪腰枣优良单株果实品质的主成分分析及综合评选

根据果实主要品质的差异,应用主成分分析法和聚类分析法对武隆猪腰枣的20个优良单株进行综合评价和分类。结果表明:武隆猪腰枣品质由酸脆口感、VC含量、果实大小形状及甜度4个主成分构成,其中酸脆口感的贡献率最大,占28.628%。20个优良单株中,综合营养价值高且口感偏酸脆的是4号、9号和10号,VC含量最高的是20号,核小、可食率高的是24号,个大偏圆的是1号,甜度最高的是15号。20个优良单株可划分为4个果实品质差别较大的类群。     

ABA和乙烯利处理对京优葡萄果皮花色苷和果实品质的影响

以京优葡萄为试材,研究不同浓度ABA和乙烯利处理果穗对果皮花色苷含量及果实品质的影响.结果表明,ABA和乙烯利处理皆能促进果实软化、有机酸降解、可溶性固形物和果皮色素积累,具有促进果实成熟的作用.乙烯利软化果实的效果明显好于ABA,但促进果实可溶性固形物积累的效果弱于ABA.300 mg/L ABA和乙烯利处理的催熟效果不明显,仅能使果实提前3～6d成熟;高浓度乙烯利处理(600 mg/L和900 mg/L)可以有效促进果实成熟,但会导致着色不良、裂果和落果等问题;600 mg/LABA处理效果最佳,可以使果实提前13～16 d成熟,且果实理化指标皆能满足商品要求.     

不同类型果袋对葡萄果实有关性状的影响

以晚熟葡萄品种红地球为试材,探讨了几种不同透光率的果袋对葡萄果实有关性状的影响,结果表明:不透光的复合袋极为显著地降低果实单粒重、总糖含量和糖酸此;透光率为16％的红色袋显著降低果实糖酸比,但对总糖含量、单粒重无显著影响;透光率为60％的无纺布袋对果实品质有一定提高作用;套袋处理的果实钙含量显著低于对照,且随着果袋透光率的降低而降低;透光率高的果袋袋内果实单宁含量偏高;各处理果实Vc含量均无显著差异.葡萄果实对光照强度的需求存在临界值,当袋内光照强度低于外界自然光照的1.4％左右时,果实生长发育开始受到影响.