Effect of processing and storage on protein and lipid composition of peas

Changes in protein and lipid contents of peas (P. sativum L.) at various stages of processing and storage at different temperatures over a six-month period were studied. Blanching had very little effect on protein or protein amino acids of peas while free amino acids were greatly affected. Immediately after bottling and canning peas, total protein differed little from that of blanched, unpackaged peas. However, free amino acids decreased much more than did protein amino acids. Storage of canned peas for six months at room temperature caused changes in some protein amino acids.Total lipids of fresh peas did not change after blanching, bottling or canning. After storage for six months, no changes were observed in the total lipids while there were increases in glycolipids and decreases in phosphatides.Increases in monogalactosyl diglycerides and decreases in digalactosyl diglycerides were also observed.     

酸菜发酵工艺与贮藏特性的研究进展

酸菜作为我国传统的发酵蔬菜制品,在国内尤其是在东北地区深受人们喜爱,有着悠久的历史文化。经发酵后酸菜不仅保留蔬菜原有的营养成分,而且具有清新爽口,开胃促消化等优点。本文主要对酸菜的发展现状、发酵工艺以及护色、防腐等贮藏特性进行了总结归纳,剖析了我国酸菜产业当前存在的主要问题,并对酸菜产业的发展前景作出展望,以期为我国酸菜产业更快速更稳定的发展提供理论支撑参考。      

无盐酸菜在发酵和贮藏过程中品质的变化

目的:探究无盐并接种乳酸菌发酵酸菜过程及低温贮藏过程中品质变化规律。方法:分析无盐酸菜发酵过程中的基本理化指标及贮存期间的品质变化。结果:无盐酸菜在发酵第5天达到成熟,发酵过程中,pH值、亚硝酸盐含量、还原糖含量和维生素C含量显著下降(P<0.05),其中维生素C含量减少了88.62%,总酸和总有机酸水平显著上升(P<0.05)。发酵成熟时,亚硝酸盐含量极低,达(0.23±0.10) mg/kg;其中有机酸主要为乳酸、草酸和醋酸,除琥珀酸外,其他有机酸如草酸、柠檬酸等发酵后均有增加,乳酸含量增加了26.5倍。4℃贮藏60 d,无盐酸菜的pH值、总酸含量无明显变化,亚硝酸盐含量持续降低。结论:发酵过程有效提高了无盐酸菜的酸味和鲜味,并保证了其优良的感官品质,且4℃下的贮藏性能良好,贮藏期为60 d。     

Effect of Rhizopus fermentation on the lipid composition of cassava flour

Studies were made on the complex lipid and fatty acid compositions of commercial cassava flour before and after nutritional ‘upgrading’ with Rhizopus arrhizus. The flour lipids closely resemble those found in other plant tissues except for a lower content of polyunsaturated acids and a higher content of free fatty acid. This can be accounted for by degradation during processing. Rhizopus fermentation leads to the appearance of γ-linolenic acid and changes in the percentage of other acids. The total lipid content falls and the typical plant glycolipids disappear to be replaced by mould phospholipids. Sterol glycoside present in the original flour is not metabolised and becomes a major component of the final material.     

Impact of fermentation conditions and refrigerated storage on microbial quality and biogenic amine content of sauerkraut

White cabbage (Brassica oleracea L. var. capitata cv. Bronco) was fermented, at 0.5% and 1.5% NaCl, using Lactobacillus plantarum or Leuconostoc mesenteroides as starter cultures and, subsequently, sauerkraut was stored at 4 °C for 3 months. Microbial populations and six biogenic amines (putrescine, cadaverine, histamine, tyramine, spermine and spermidine) were investigated. Fermentation and storage increased aerobic mesophilic bacteria and LAB populations in sauerkrauts, and this was accompanied by a rise in biogenic amine content. L. plantarum sauerkrauts produced with 0.5% NaCl had the highest microbial counts, whilst no differences between salt contents were found with L. mesenteroides. Total biogenic amine amount was lower at 0.5% NaCl than at 1.5% in both induced fermentations and L. mesenteroides produced a lower content than did L. plantarum. Spermidine was the major contributor to the total biogenic amine content, followed by putrescine, whilst histamine was present at the lowest level. The individual and total biogenic amine levels in the experimental sauerkrauts stored at 4 °C for 3 months were below the upper limits reported in the literature for fermented products, indicating good quality and safety of the sauerkrauts. L. mesenteroides starter and 0.5% NaCl were the optimal fermentation conditions for producing sauerkrauts with the lowest biogenic amine contents.     

混菌发酵对无盐酸菜品质特性的影响

目的:利用乳酸菌发酵无盐酸菜。方法:通过考量菌株的发酵特性和抑菌能力,筛选具有高产酸能力和抑菌能力的乳酸菌制成混合发酵剂,并对其发酵工艺进行优化。结果:植物乳杆菌和嗜酸乳杆菌的生长活性、产酸能力及抑菌能力较强,选二者为发酵菌株;最佳发酵工艺条件为m_{植物乳杆菌}∶m_{嗜酸乳杆菌}为2∶1,250 g白菜中乳酸菌接种量为450μL,玉米汁添加量为7.5 g,发酵温度30℃,此条件下制备的酸菜颜色和气味较好,感官品质最佳。结论:在无盐条件下,接种乳酸菌发酵酸菜是控制发酵过程、优化产品质量的有效手段,可以确保发酵稳定进行并获得高品质酸菜。     

乳酸菌发酵对富源酸菜品质及安全性的影响

采用液态发酵方式,比较乳酸菌发酵和自然发酵的富源酸菜在整个贮藏过程中不同时段的感官、理化指标和微生物变化的规律,评价两种发酵方式对富源酸菜品质及安全性的影响。试验结果表明:与自然发酵相比,乳酸菌发酵的富源酸菜感官品质更优;亚硝酸盐含量较低且亚硝峰值出现得较早、pH值较低、总酸含量较高;乳酸菌活菌数量更多,菌落总数、霉菌和酵母菌数量都较少;大肠杆菌未检出。说明乳酸菌发酵制作的富源酸菜在品质及安全性方面都优于自然发酵的富源酸菜。     

Effect of maturity, processing, and storage on the furanocoumarin composition of grapefruit and grapefruit juice

Since the early 1990's, grapefruit juice has been implicated in drug interaction with various furanocoumarins (FCs) now associated with the effect. Although FCs are present in various fruits and vegetables, it is their presence in grapefruit that has attracted the most attention. Studies have shown that FCs in grapefruit juice can vary significantly and from multiple causes. Most of all, FCs are stress-induced molecules, their levels affected by many factors ranging from UV exposure to insect infestation. There are also varietal and seasonal factors. In this study, juice processing and storage parameters were investigated. Prolonged fruit storage prior to processing and most steps involved in juice processing had little influence on the levels of 6',7'-dihydroxybergamottin (DHB), paradisin C, or bergamottin. However, products that were hot filled or stored at room temperature had lower amounts of DHB and paradisin C and higher amounts of bergaptol compared to juices that were not hot filled and stored at refrigerated temperatures. Both DHB and paradisin C are potent CYP3A4 inhibitors, while bergaptol is a very weak inhibitor. Bergamottin amounts decreased to a lesser extent. Therefore, grapefruit juice products that were hot filled or have been stored at room temperature for an extended period of time will have a reduced drug interaction potential.     

Effect of growth temperature on yeast lipid composition and alcoholic fermentation at low temperature

The loss of viability of wine yeast strains due to low-temperature fermentations could be overcome by increasing their stress tolerance and adaptability. Changes in membrane lipid composition are one of the first responses to cold stress. The aim of this study was to analyze the various adaptation mechanisms to low temperatures by comparing the better adapted Saccharomyces species. The viability, vitality, fermentation capacity, and lipid composition of different Saccharomyces species (S. cerevisiae, S. bayanus, S. uvarum, and a hybrid S. cerevisiae/S. uvarum) with different fermentative origins (wine, beer, and baker’s strains together with a laboratory strain) were compared after culturing at low (13 °C) and optimal (25 °C) temperatures. In spite of specific responses of the different strains/species, the results showed that at low temperature, the medium-chain fatty acid and the triacylglyceride content increased, whereas the phosphatidic acid content and the phosphatidylcholine/phosphatidylethanolamine ratio decreased. Only the laboratory strain was not able to ferment the sugars, and after growing at both temperatures, its lipid composition was very different from that of the other strains. The hybrid strain showed the highest sugar consumption at 13 °C and the best vitality whatever the preculture temperature used. The rest of the species needed a preadaptation at low temperature involving a change in their lipid composition to improve their fermentation rate at 13 °C.     

Effect of processing methods on product characteristics,lipid, fatty acid composition and oxidative stability of smoke-dried beef

Smoke-dried beef was pre-processed with water or by pressure cooking, weight losses were 50 and 54% respectively, with the rate of drying faster in the latter. There was a greater loss of total lipid and triglycerides in pressure cooked samples but the reverse was true for the phospholipids. The proportions of saturated and monoenoic fatty acids were slightly higher in the water cooked products although total unsaturation was slightly lower, the values being 37 and 39%, respectively. The fatty acid composition of the phospholipids was similar for both treatments except that the levels of polyenoic fatty acids were 16.4 and 14.43%, respectively in water and pressure cooked samples. Of the polyenes C20:4 accounted for about 75% of the fatty acids in the water cooked samples, compared with 40% with pressure cooking. After 60 weeks of storage at room temperature, pressure cooked samples were found to be more stable oxidatively: malonaldehyde was the principal oxidative by-product in both treatments.     

Effect of fermentation temperature and culture media on the yeast lipid composition and wine volatile compounds

The temperature of a wine fermentation strongly affects lipid metabolism and thus, aromatic profiles. Most of the metabolic studies are done in well-controlled laboratory conditions, yet wine is produced in less-reproducible industrial conditions. The aim of this study is to analyse the effect of fermentation temperature (13 degrees C and 25 degrees C) and culture media (synthetic media and grape must) on yeast lipid composition and volatile compounds in wine. Our results show that yeast viability was better at 13 degrees C than at 25 degrees C whichever growth medium is used, but that the complexity of the grape must enabled cells to reach higher viable population size. Viability was also related to the incorporation of linoleic acid and beta-sitosterol, which were present in the grape must. A lower temperature modified the cellular lipid composition of yeast, increasing the degree of unsaturation at the beginning of fermentation and decreasing the chain length as fermentation progressed. We also found that medium-chain fatty acids, mainly dodecanoic acid, were present in the cell phospholipids. Wines produced from grape must were more aromatic and had a lower volatile acidity content than those derived from a synthetic medium. Fermentations that were performed at the lower temperature also emphasized this feature.     

小麦粉加工精度对挂面储藏期间脂质稳定性的影响

研究不同加工精度小麦粉对挂面储藏期间脂质稳定性影响。结果表明,挂面储藏过程中,总脂和结合脂含量总体呈现下降趋势,游离脂含量先下降后升高再下降,脂肪不断消耗;游离脂肪酸值显著升高(P<0.05),低加工精度小麦粉制得的挂面脂质水解程度较高且水解速率快,12周后脂肪酸值略有降低;低加工精度的挂面脂肪酶活显著下降(P<0.05);低加工精度挂面亚油酸含量在0～12周显著上升(P<0.05),随后显著降低(P<0.05);GC-MS测定结果表明挂面中挥发性物质乙酸、己酸和壬酸含量明显升高,加工精度越低的小麦粉制得的挂面中酸性物质含量增幅越大,氧化酸败速度越快。因此,低加工精度小麦粉制得的挂面在储藏过程中脂质水解和氧化程度较高,脂质稳定性较低。     

榨菜叶酸菜发酵剂研究

通过对蔬菜发酵中几种常见乳酸菌的发酵生理特点的研究,筛选出适合榨菜叶发酵酸菜的发酵剂,得出最优混合发酵剂为肠膜明串珠菌3%、短乳杆菌1%、植物乳杆菌1%,可生产出质地、风味俱佳,与自然发酵无明显差别的酸菜,但发酵时间从自然发酵的15d左右缩短为5d左右。     

不同加工方式与时间对猪肉脂肪含量和脂肪酸组成的影响

为研究不同加工方式和时间对猪肉脂肪酸组成、脂肪含量、营养及风味的影响,以PIC猪背最长肌为原料,经不同时间的蒸煮或烤制加工后,分别测定各样品的脂肪含量和脂肪酸组成。结果显示,加工时间主要影响PUFA/SFA和SFA+MUFA值、磷脂的含量和脂肪酸组成、肌内总脂肪酸的组成;加工方式主要影响肌内脂肪总含量、甘三酯的含量、游离脂肪的脂肪酸组成;游离脂肪酸的含量同时受加工时间和方式的影响,而甘三酯的脂肪酸组成在加工中没有明显变化。因此采用不同时间的蒸煮或烤制加工时,加工方式和时间都会对猪肉脂肪酸组成、脂肪含量、营养及风味产生影响,但加工时间对脂肪酸组成、营养和风味的影响更大,而加工方式对脂肪含量的影响更显著。     

Effect of dietary fish oil on fatty acid composition, lipid oxidation and sensory property of chicken frankfurters during storage

Broilers fed with three levels of fish oil (0, 2 and 4%) for 6 weeks were used in the manufacture of chicken frankfurters. The meat samples were vacuum-packed and stored at 0°C for 0, 10, 20 and 30 days. Cooking yield, proximate and fatty acid composition, lipid oxidation, microbial and sensory properties of the meat products were measured. Cooking yield, moisture, fat, protein, ash and cholesterol contents of frankfurters were not affected (P>0.05) by levels of dietary fish oil. Frankfurters processed from chickens fed diets enriched with 2 and 4% of supplemental fish oil had a higher (P<0.05) level of n-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid), but had a lower level of n-6 fatty acids (P<0.05) than the controls (0% fish oil). TBA values and pH values of meat samples were not affected (P>0.05) by levels of supplemental fish oil in the diets, however, pH values of the vacuum-packaged chicken frankfurters decreased (P<0.05) as the storage time increased. No differences (P>0.05) in total anaerobic plate counts were observed among the fish oil treatments during storage. Supplementation of 2 and 4% fish oil in the diets did not increase (P>0.05) the intensity of fishy flavor in chicken frankfurters.     

接种发酵和自然发酵酸菜的亚硝酸盐含量对比分析

目的:对比乳酸菌接种发酵法和自然发酵法生产酸菜中的亚硝酸盐变化情况,考察不同发酵方式对酸菜中亚硝酸盐含量的影响.方法:采用离子色谱法测定酸菜中的亚硝酸盐含量,对发酵过程中不同时间采集的样品进行分析,动态监测2种发酵方式中亚硝酸盐的产生和变化情况.结果:酸菜发酵过程中亚硝酸盐呈现先升后降的趋势,乳酸菌接种发酵法生产的酸菜在发酵过程中亚硝酸盐一直处于较低水平,在5d出现峰值,发酵至15d亚硝酸盐几乎消失.而自然发酵法生产的酸菜发酵初期亚硝酸盐含量较高,峰值出现在7d,含量为20.84mg/kg,超过国家标准限度值,为达到绿色、安全和健康饮食的目的,最好将发酵周期控制在30d以上.结论:同样的发酵条件下,乳酸菌接种发酵法生产酸菜的生产周期更短,安全性优于自然发酵法的.     

黄浆水在酸菜腌制过程中的应用

以乳酸菌粉为发酵剂,加入营养丰富的黄浆水配成发酵液发酵酸菜.实验在室温条件下分成三组进行.第一组做对照组,第二、三组分别用加入了30％和60％黄浆水的盐水做发酵液.对酸菜的感官性质进行评价;分阶段测定酸菜的pH值、可滴定酸度、亚硝酸盐含量,以此衡量其添加的黄浆水对酸菜性质的影响.结果表明,黄浆水可以提高发酵速度,让酸菜快速成熟,而且不会增加亚硝酸盐的含量.加入了30％黄浆水的第二组比对照组早十天左右达到了可食用酸度,60％黄浆水的第三组酸度增加得也很快,但是感官性质不佳.