地下储油与地上储油对油脂品质的影响北大核心CSCD

油脂在储存过程中,其品质指标易受温度等因素的影响。将大豆原油和菜籽原油储存于室外地上和埋于室外地下的钢制储罐,定期取样测定油脂的水分及挥发物、酸值、过氧化值、色泽、挥发性成分、脂肪酸组成、反式脂肪酸含量、氧化稳定性及甾醇和维生素E含量,考察不同储油方式对大豆原油和菜籽原油品质的影响。结果表明:地下储油温度变化较小,基本在11~27℃之间,地上储油温度变化较大,最高接近45℃,最低接近0℃;地上、地下储油中均未检出反式脂肪酸,储油方式对油脂水分及挥发物、色泽、脂肪酸组成影响较小;储存12个月时,地上、地下储存大豆原油酸值升幅分别为83.3%、12.5%,地上、地下储存菜籽原油酸值升幅分别为86.4%、19.0%,地上、地下储存大豆原油过氧化值升幅分别为243%、218%,地上、地下储存菜籽原油过氧化值升幅分别为219%、167%;地下储油的氧化稳定性优于地上储油,地下储油对部分重要挥发性成分和甾醇、维生素E等油脂营养成分的的保留效果优于地上储油。总的来说,地下储油是良好的油脂品质保鲜技术,不但能控制氧化速率,对营养价值及风味的保持效果也较好。     

Inverse relationship between oil content and specific gravity of groundnut kernels

Thirty-two samples of groundnut kernels were analysed for oil content by the standard Soxhlet extraction procedure. The oil content ranged between 425.6 and 549.5 g kg^?1. The specific gravity of groundnut kernels was determined both for the whole kernels and the split kernels (cotyledons with testa). The specific gravity of whole kernels varied between 0.9358 and 1.0730 while that of split kernels between 1.0547 and 1.1227. A highly significant correlation (r = -0.9459) was found between oil content and specific gravity of split kernels. It should, therefore, be possible to predict the oil content of the groundnut samples on the basis of specific gravity of split kernels.     

Soybean seed storage: Packaging technologies and conditions of storage environments

Artificial refrigeration is sufficient for maintaining the quality of soybean seeds in storage in processing plants, but when lots are distributed to rural producers, they are often kept in natural environments, without temperature or relative humidity control, which decreases their germination rates. This research aimed to evaluate different storage conditions and technological packaging for soybean seeds. The first stage evaluated the quality of soybean seeds stored at different temperatures for up to one year in raffia bags with or without polyethylene inner liners. The second stage evaluated the quality of soybean seeds stored in a natural atmosphere in raffia or laminated packaging, in a modified atmosphere with polyethylene packaging, in a refrigerated atmosphere with raffia or laminated packaging, or in a modified and refrigerated atmosphere with polyethylene packaging. An increase in storage time had a negative influence on the quality of the stored seeds. Storage temperature was the main influence in the reduction in seed physiological quality. Storage of soybean seeds in raffia packaging coated with polyethylene in a natural-temperature environment resulted in seeds retaining similar physical and physiological qualities to those stored under refrigeration. Raffia packaging coated with laminated material maintained the best physical and physiological quality of soybean seeds stored over time. Optimal packaging technology with laminated coating in “big bag” format has replaced the conditioning of storage environments with the maintenance of the quality of soybean seeds over time. The packaging technology is an excellent alternative for the soybean processing units.     

Comparison of chemical and sensory methods of evaluating thermally oxidised groundnut oil

Seven chemical methods, namely peroxide value (PV), totox value (TV), anisidine value (AV), conjugable oxidation products (COP), oxodiene value (OV), induction period (IP), iodine value (IV) and a sensory analytical procedure (flavour score, FS) have been used in evaluating the oxidation state of groundnut oil heated at 100°C for varying lengths of time up to 20 h. As oxidation progressed, PV, TV, AV, COP and OV increased. IP and IV decreased with oxidation while FS showed a progressive deterioration on a seven-point scale from bland to very rancid. On the basis of sensitivity to oxidative changes, five of the methods (PV, TV, IP, IV and FS) were found to be satisfactory. However, the best correlation with flavour scores were obtained in the case of IP, IV and OV while AV and COP correlated poorly with FS. Three methods (PV, IP and IV) best satisfied the combined criteria of sensitivity to oxidative changes and correlation with flavour.     

油脂充氮储藏技术的研究

探讨了油脂储藏过程中影响油脂氧化的因素及防控措施,并重点研究了充氮对油脂氧化的延缓。     

地下储油与地上储油对大豆油综合品质的影响

为了研究地下储油的可行性,将大豆油分别置于室外地上和地下室的钢制油罐（单罐容量200 kg）中储存,地上储油分别采用常规储存、添加抗氧化剂TBHQ储存、充氮储存,地下储油采用自然低温储存,储期24个月,期间自动检测和记录储油温度,每月取样检测大豆油的酸值、过氧化值、维生素E含量和甾醇含量,分析不同储油条件对大豆油综合品质的影响。结果显示：地上储油的全年周均温度为19.5 ℃,最高温度接近40 ℃,最低温度接近0 ℃,夏季（6—9月）月均温度为33 ℃,冬季（12月至次年3月）月均温度接近10 ℃;地下储油的全年周均温度为16.8 ℃,常年日均温度在12～21 ℃之间。经24个月储存,4种储油的酸值均未超出国标限量,但地上常规储油的酸值升幅明显高于其他3种储油,其过氧化值在7个月时已超标,地下储油和地上添加TBHQ储油的过氧化值至24个月也未超标,充氮储油的过氧化值在17个月时开始超标,地下储油的保质期比地上常规储油延长了17个月。随储存时间延长4种储油中维生素E、甾醇含量均持续降低,但与地上常规储油相比,地下储油中维生素E、甾醇损失率分别下降19.36、8.57个百分点。与地上储油相比,地下储油依赖于自然的恒定低温和避光条件,在不添加抗氧化剂和不充氮的条件下可实现对大豆油的保质保鲜储存,是一种绿色安全和优势明显的储油技术,值得推广应用。     

Spoilage moulds and deterioration of the Nigerian groundnut cake snacks under three storage methods

Twelve species of toxigenic and zoopathogenic fungi were isolated from three major types of the Nigerian groundnut cake snacks. All the isolates grew well on groundnut cake infusion medium and induced changes in the oil (decrease) and free fatty acid (increase) contents of groundnut seed medium with time. The largest changes were induced by Aspergillus flavus, A. niger and A. fumigatus. Mould deterioration of groundnut cake snack samples kept under traditional, “industrial” and retailer's storage methods was studied. Mouldiness was first recorded on the 5th day for samples stored under the retailer's method and on the 10th day for samples from other storage methods. The odour and taste acceptability values, although partly affected by the different storage techniques decreased rapidly with storage period. The overall results suggest the need for research into the processing and packaging to extend the shelf life of the snacks.     

不同储存条件对胡麻油品质的影响

通过测定酸价和过氧化值,研究温度、光照和空气等储存条件对胡麻油品质的影响.结果表明,温度升高导致酸价和过氧化值升高,光照条件下酸价和过氧化值也明显高于避光条件,随储存时间延长,空气氧化使胡麻油品质下降.     

Salmon by-product storage and oil extraction

Oils extracted from wild salmon by-products are excellent sources of long chain omega-3 polyunsaturated fatty acids including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, quality loss is expected if time delays are encountered before oil extraction. The free fatty acid levels (FFA), fatty acid profile and total fat soluble antioxidant activity in extracted oil from aging pink salmon heads and viscera stored at two temperatures (6 and 15 °C) for four days were determined. The FFA values in raw salmon heads and viscera increased with storage time and temperature. A significant difference (p < 0.05) from the starting material was noted at day 1 at both temperatures for FFA. Fatty acid composition data indicated no changes in the levels of long-chain omega-3 fatty acids with the respective temperature. The concentration of long-chain omega-3 fatty acids EPA ranged from 9.3 to 11.3 g/100 g of crude oil and DHA ranged from 12.3 to 13.1 g/100 g of crude oil. The antioxidant activity of the pink salmon oils at day 0 was 0.89 ± 0.15 μmole Trolox equivalent/g of crude oil. Significant decreases (p < 0.05) from the starting material were noted on day 2 for 15 °C samples and day 3 for 6 °C samples. After four days of storage antioxidant levels (Trolox equivalent/g of crude oil) were approximately 25% of initial values. Oil extracted from raw salmon heads and viscera remained a good source of long chain omega-3 fatty acids even after 4 days of raw material storage at 15 °C; however, fat soluble antioxidant activity was reduced and free fatty acid levels increased with increased raw material storage temperature and time.     

橄榄油储藏稳定性研究

将橄榄油和3种常用油脂储存在高温、常温、低温、光照和避光等6种不同的条件下,研究其储藏稳定性。通过分析储藏期间油脂的过氧化值,表明橄榄油的氧化稳定性最好。同时高温光照条件下,橄榄油中生育酚的含量降低最快。常温避光和低温避光下,橄榄油的品质变化不明显,是橄榄油储藏的适宜条件。     

大豆油在储存过程中的变化

收集储备大豆原油在储存过程中酸值和过氧化值的数据,分析其在储存过程中的变化规律。结果表明:大豆原油的酸值和过氧化值变化规律相同,酸值随着储存时间的延长呈缓慢线性增长,年变化值在0.2～0.4 mg/g,过氧化值随着储存时间延长呈平稳慢慢上升趋势,其变化值受环境温度影响较大,在外部温度和氧气突然增加时过氧化值迅速上升,当达到一定值后分解下降。     

番茄红素对核桃油贮藏品质的影响研究

番茄红素具有淬灭单线态氧和清除过氧化自由基、抑制脂质过氧化的功能,本研究在核桃油中添加0.005％的番茄红素,以同等添加量的TBHQ、BHT、BHA、α-生育酚为阳性对照,以不添加任何抗氧化剂的核桃油为空白对照,测定核桃油在贮藏过程中酸价和过氧化值的变化。结果表明：同等添加量的抗氧化剂在核桃油中抗氧化能力大小为：TBHQ>番茄红素>BHA>BHT>α-生育酚。为了进一步评价番茄红素对核桃油贮藏品质的影响,测定其在贮藏过程中δ-生育酚、总酚、角鲨烯、脂肪酸的含量变化。结果表明：在25 ℃避光贮藏150天后,添加0.005％番茄红素的核桃油样中δ-生育酚、总酚和角鲨烯的含量分别降低到33.76 mg/kg、200.54 mgGAE/kg、14.03 mg/kg,而未添加抗氧化剂的核桃油样中δ-生育酚、总酚和角鲨烯的含量分别降低到30.98 mg/kg、110.75 mgGAE/kg、13.83 mg/kg;5种脂肪酸的含量也发生了不同程度的变化。研究发现在核桃油中添加0.005％的番茄红素,可有效延缓油脂的氧化酸败,提高油脂中活性成分的保存率,有助于延长其贮藏和货架期。     

茶油贮藏的稳定性及高效液相色谱分析

以过氧化值和酸值作为油脂的评价指标,探讨温度、光线对茶油稳定性的影响;采用Schaal烘箱法(62±1)℃,以POV含量为指标,结合固相萃取—高效液相色谱法研究多酚类物质(没食子酸、3,4-二羟基苯乙酸、槲皮素)对茶油的抗氧化性能.结果表明:高温和光照都可以显著加速茶油氧化,降低茶油的稳定性;多酚类物质可以提高茶油的稳定性,其抗氧化能力随加入量增大而增强,其中3,4-二羟基苯乙酸＞槲皮素＞没食子酸.     

不同植物油体蛋白及其油体贮藏最适温度关联研究

以仁用杏、油桐、花生、大豆、芝麻和油茶种子为试材,研究不同植物油体蛋白的组分差异,并结合其脂肪酸成分含量分析不同温度下油体贮藏效果。结果表明,前3种植物油体蛋白组分较多,而后3种植物油体蛋白组分相对较少;植物油体蛋白组分越多,油体差异个体也越多,同时某组分油体蛋白基因表达量越多,其对应大小的油体也越多;在4℃冷藏条件下植物油体均能达到一个较长时间保鲜的效果,但并不是温度越低油体贮藏效果越好,脂肪酸成分和油体蛋白综合影响植物油贮藏效果。     

鱼油纳米乳的制备及贮藏稳定性研究

采用高压均质法,以乳清分离蛋白(WPI)乳化包埋鱼油制备鱼油纳米乳。采用单因素实验研究了主要因素对包封率和吸光比(SRI)的影响,并以包封率为指标,进行正交实验优化工艺配方。同时以不同压力处理的鱼油纳米乳为对照,分别考察了4、25℃条件下鱼油纳米乳的贮藏稳定性。结果表明:最佳工艺配方为乳清分离蛋白质量浓度25 g/L,鱼油添加量100 g/L,均质压力80 MPa,均质次数4次。采用最佳工艺配方制备的鱼油纳米乳的包封率为96.4%,SRI为0.113。稳定性实验结果表明鱼油经纳米乳包埋可显著提高鱼油氧化稳定性,高压处理有利于提高鱼油纳米乳的稳定性,鱼油纳米乳在4℃的贮藏稳定性高于25℃的贮藏稳定性,80 MPa处理鱼油纳米乳经4、25℃放置30 d乳析指数分别为0、1.4%,鱼油纳米乳经25℃放置60 d后过氧化值及渗漏率分别为4.25 meq/kg、5.89%。     

Effect of ammoniation on the carcinogenicity of aflatoxin-contaminated groundnut oil cakes: long-term feeding study in the rat

The efficacy of detoxication by ammoniation of aflatoxin-contaminated groundnut oil cakes was determined in long-term (18 months) feeding experiments with rats. The aflatoxin content of the cake was reduced very considerably by the pressurized application of ammonia, dropping from 1000 to 140 ppb at a gas pressure of 2 bar and to 60 ppb at 3 bar. No reversion was noted during the experiment. The percentage of hepatic tumours obtained was very high for the untreated cakes, but fell sharply with medium treatment and was reduced to zero by the treatment at 3 bar. A satisfactory dose-effect relationship was shown between the residual aflatoxin content of the cakes and the observed incidence of tumours. The results show that ammonia treatment is a practical solution to the problem of the carcinogenic potency of contaminated oil cakes.     

Rats fed blended oils containing coconut oil with groundnut oil or olive oil showed an enhanced activity of hepatic antioxidant enzymes and a reduction in LDL oxidation

The effects of feeding Wistar rats with blended and interesterified oils of coconut (CO):groundnut (GNO) or CO:olive (OLO) on liver antioxidant enzyme activities and susceptibility of LDL to oxidation were studied. The hepatic lipid peroxidation (LPO) levels in the rats fed CO:GNO blend and interesterified oils were increased by 31% and 21%, when compared to the rats given CO. The superoxide dismutase activity was increased by 31% and 28%, and catalase (CAT) activity was increased by 37% and 39%, respectively, in rats given blends and interesterified oils of CO:GNO, as compared to those given CO. The activities of glutathione peroxidase (GPx) were increased by 17% and 20% in rats given CO:GNO blend and interesterified oils. Glutathione transferase (GST) level was also found to be increased by 26% and 31% after feeding blended and interesterified oils of CO:GNO, compared to those given CO. The LDL oxidation, which was elevated by feeding GNO, was found to be reduced by 10% and 14%, respectively, in the groups fed blended and interesterified oils of CO:GNO. Similarly, CO:OLO blended oils enhanced SOD, CAT, GPx and GST activities by 34%, 43%, 27% and 23%, respectively, compared to the rats given CO-containing diets. The corresponding increases in theses antioxidant enzyme activities when CO:OLO interesterified oils were fed to rats were 38%, 50%, 28% and 26%, respectively, when compared to rats given CO-containing diets. There was a significant reduction in hepatic LPO as well as oxidation of LDL, when blended and interesterified oils of CO:OLO were fed to rats. The results demonstrated that blended and interesterified oils of CO with GNO or OLO enhance hepatic antioxidant enzymes, decreased lipid peroxidation in liver and reduced the susceptibility of LDL to oxidation.     

微波预处理对亚麻籽油得率及其贮藏稳定性的影响

对亚麻籽进行微波预处理,并采用微波辅助溶剂法提取亚麻籽油。以亚麻籽油得率为指标,对微波预处理亚麻籽工艺条件进行优化,同时比较了经微波预处理和未经微波预处理提取的亚麻籽油得率、贮藏稳定性和多酚含量。结果表明:微波预处理最佳工艺条件为原料水分含量6%、微波功率65 W、微波时间3 min,在此条件下亚麻籽油得率为46. 60%,比未经微波预处理的提高了8. 05个百分点;在105℃贮藏8 d内,经微波预处理和未经微波预处理提取的亚麻籽油的过氧化值增加量分别为4. 38 mmol/kg和18. 16 mmol/kg,K_(232)的增加量分别为2. 53、9. 04,K_(270)的增加量分别为0. 09、0. 35;与未经微波预处理相比,微波预处理可将亚麻籽油中的多酚含量提高14. 9%。微波预处理能提高亚麻籽油得率和多酚含量,同时可延缓亚麻籽油氧化的速率,进而提高其贮藏稳定性。