Original article: Incorporations of blueberry extracts into soybean‐protein‐isolate film preserve qualities of packaged lard

The effect of blueberry‐extract incorporation into soybean‐protein‐isolate edible film on the quality of packaged lard was compared with vitamin E or butylated hydroxyl anisole (BHA) incorporations individually during the storage at 36 °C and relative humidity of 40% for 5 weeks. Blueberry‐extract incorporations into soybean‐protein‐isolate film showed a greater tensile strength, lower water vapour permeability and lower oxygen permeability than vitamin E or BHA incorporations individually. On the other hand, the antioxidant capacity of soybean‐protein‐isolate film incorporated with the blueberry extract was greater than that incorporated with vitamin E and similar to that incorporated with BHA. Moreover, soybean‐protein‐isolate film incorporated with the blueberry extract showed a greater capacity to delay the lard hydrolysis than that incorporated with BHA, and a similar capacity to that incorporated with vitamin E. Consequently, blueberry‐extract incorporations into soybean‐protein‐isolate film not only improved mechanical and barrier properties, but also delayed the oxidation and hydrolysis of packaged lard. Therefore, blueberry‐extract incorporations into soybean‐protein‐isolate films have potential as a packaging material which will preserve the qualities of stored lard.     

Volatile compounds in oils after deep frying or stir frying and subsequent storage

Soybean oil (900 g) was heated by deep frying at 200°C for 1 h with the addition of 0, 50, 100, 150 and 200 mL water, and then stored at 55°C for 26 weeks. Soybean oil, corn oil and lard were heated by stir frying and then stored at 55°C for 30 weeks. The volatiles and peroxide values of these samples were monitored. All samples contained aldehydes as major volatiles. During heating and storage, total volatiles increased 260-1100-fold. However, aldehyde content decreased from 62–87% to 47–67%, while volatile acid content increased from 1–6% to 12–33%; especially hexanoic acid which increased to 26–350 ppm in the oils after the storage period was completed. Water addition to the oils heated by deep frying tended to retard the formation of volatile compounds. The total amount of volatile constituents of lard heated by stir frying increased more during storage than that of corn oil or soybean oil. Peroxide values did not reflect the changes of volatile content in the samples.     

Enzymatic interesterification of lard and high-oleic sunflower oil with Candida antarctica lipase to produce plastic fats

Lard and high-oleic sunflower oil (Trisun® Extra) were interesterified at 55°C for 24 h with SP435 lipase from Candida antarctica to produce plastic fats. As the amount of trisun increased, percentage free fatty acid, unsaturated fatty acid/saturated fatty acid value, oxidizability, and the amount of 18:1 found at the sn-2 position of triglyceride products increased. Differential scanning calorimetry showed that the low-melting components in the product contained more 18:1 than the high-melting components. A 60:40 (w/w) ratio of lard to trisun had the widest plastic range (3–26°C). The scaled-up reaction to produce this blend resulted in a product that had 60.1% 18:1 at the sn-2 position compared to 44.9% for the physical blend. The solid fat content of the 60:40 interesterified mixture resembled soft-type margarine oil.     

猪油醇解工艺的研究

介绍了适用于制备改性醇酸树脂合成中的猪油醇解工艺 ,确定了适宜的催化剂种类、用量及工艺条件     

Effect of feeding partially hydrogenated lard on trans-fatty acid content of muscle and backfat of heavy pigs

The incorporation of fat in diets for heavy pigs may be necessary in order to increase their energy intake in the finishing period. Lard may be a good lipid source but it contains 10–13% of linoleic acid, which makes the subcutaneous fat less suitable for long term curing of raw ham. Partial hydrogenation of lard decreases linoleic acid content, but increases trans-fatty acid content.

This trial involved two groups of pigs of 114 kg live weight, fed for the last two months before slaughter with diets containing 3% lard (L) or 3% partially hydrogenated lard (PHL). The PHL contained about 10% trans-fatty acids and 2.5% linoleic acid.

Rearing performance and carcass characteristics were unaffected by treatment. The group fed PHL showed a lower percentage of linoleic acid in the backfat (PHL 12.28% vs. L 13.04%) and a higher percentage of C18:1 trans-fatty acids both in backfat (0.5% vs. 0.06%) and in intramuscular fat (0.2% vs. 0.04%).     

负载二氢槲皮素的甘油解猪油微乳液体外抗氧化性及消化性

为解决含甘油解猪油的食品在贮藏过程中易被氧化的问题,向甘油解猪油中加入二氢槲皮素,制备负载二氢槲皮素的甘油解猪油微乳液,通过体外模型测定该微乳液的还原力以及对DPPH、ABTS和羟自由基的清除能力,探讨含二氢槲皮素甘油解猪油微乳液的体外抗氧化性,同时通过体外模拟胃肠消化测定其消化性。结果表明：该微乳液具有一定的还原力及DPPH、ABTS、羟自由基的清除能力,且还原力及自由基清除能力均随着二氢槲皮素负载量的增加而升高,相关性显著;该微乳液经胃消化2 h后二氢槲皮素的保留率为79.25%,说明该微乳液能有效保护二氢槲皮素实现靶向性肠道输送,在肠道消化2 h后,微乳液的游离脂肪酸释放率达到73.85%,二氢槲皮素生物利用率达33.3%。综上,负载二氢槲皮素的甘油解猪油微乳液在食品工业中有较大的应用潜力。     

红树莓叶片中黄酮类物质提取及抗氧化性的研究

以小浆果果树红树毒叶片为实验材料，利用分光光度法测定其总黄酮含量，并采用烘箱贮存法研究了不同添加量红树毒叶片提取物粗黄酮在猪油中的抗氧化性。结果表明：鲜样中红树毒叶片总黄酮含量是278．73mg／100g，干样中是533．71mg／100g；红树毒叶片提取物粗黄酮对猪油有一定的抗氧化作用，并随添加量的增加而增强；增效剂以(柠檬酸)对红树毒叶片提取物粗黄酮无增效作用，而Vc具有一定的增效作用。抗氧化活性顺序为：0．02％槲皮素＞0．02％PG＞0．02％BHT＞0．4％粗黄酮＞0．05％粗黄酮 0．05％Vc＞0．2％粗黄酮＞0.1％粗黄酮＞0．05％粗黄酮＞0．02％粗黄酮＞0．05％粗黄酮 0．05％CA＞对照。     

影响猪油干法分提因素探讨

猪油是不同甘油三酯组成混合物,其中S3含量为5％,S2U含量为32％~39％,SU2含量为 46％~60％,U3含量为3％~10％,可通过干法分提把熔点相差较大甘油三酯分离。影响猪油干法分提 参数有:结晶温度、冷却速率、养晶时间、搅拌速率及分离方式。干法分提结晶温度为20~26℃(由冷却 曲线决定),冷却速率为2~6℃／h,养晶时间为6~12 h,搅拌速率为0~50 rmp,可采用离心或过滤(真 空或压力过滤)等分离方式,这些条件决定分提效果。     

酶法猪油改性制人乳脂替代品的研究

人乳是人类提供给婴儿的最佳食品，其脂肪具有独特的结构，棕榈酸主要分布在Sn-2位，猪油的Sn-2位与其相似的结构。采用具有Sn-1,3催化专一性的Lipozyme IM作催化剂，游离脂肪酸作酰基供体进行酯交换改性猪油来制备人乳脂替代品。采用响应面法设计优化实验。其最优条件为：水分含量3.7%(以酶量计）；反应温度61℃，底物比：脂肪酸：猪油2.4:1（摩尔比）；酶量10%（以底物质量计），反应时间1h。     

芝麻饼提取物对猪油抗氧化作用研究

采用碘量法测定了芝麻饼甲醇提取物对猪油的抗氧化作用。结果表明,芝麻饼提取物有较强的抗猪油自动氧化能力。随着芝麻饼提取物浓度的增加,其抗氧化作用逐渐增强,抗坏血酸、柠檬酸对其具有一定的协同抗氧化作用。