地下储油与地上储油对大豆油综合品质的影响

Effect of underground storage and above-ground storage on quality of soybean oil

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。

In order to study the feasibility of underground oil storage,soybean oil was stored outdoor above-ground and basement steel tanks(single tank capacity 200 kg)for 24 months,respectively,with conventional storage,antioxidant-added TBHQ storage,and nitrogen-filled storage for outdoor storage and natural low-temperature storage for underground storage.The storage temperature was automatically detected and recorded,and the acid value,peroxide value,vitamin E content and sterol content of soybean oil were evaluated monthly.The effect of different storage conditions on the overall quality of soybean oil was investigated.The results showed that the annual average weekly temperature of above-ground storage was 19.5℃,with the maximum temperature close to 40℃and the minimum temperature close to 0℃,and the monthly average storage temperature in the summer(from June to September)was 33℃,the monthly average storage temperature in the winter(from December to March of following year)was 10℃;the annual average weekly temperature of underground storage was 16.8℃,and the year-round average daily oil temperature ranged from 12℃to 21℃.After 24 months of storage,the acid value of the four soybean oils did not exceed the national standard limit,but the acid value of the above-ground conventional storage oil increased significantly more than the others,and its peroxide value exceeded the standard in 7 months;the peroxide value of the underground storage oil and the storage oil with TBHQ did not exceed the standard until 24 months;the peroxide value of the nitrogen-filled storage oil began to exceed the standard in 17 months,and the shelf life of the underground storage oil was extended by 17 months compared with that of the above-ground conventional storage oil.The contents of vitamin E and sterols in the four storage oils continued to decrease with the extension of storage time,but compared with the above-ground conventional storage oil,the loss rates of vitamin E and sterols in the underground storage oil decreased by 19.36 percentage points and 8.57 percentage points,respectively.Compared with above-ground storage,underground storage without adding antioxidants and filling with nitrogen could achieve quality and freshness storage of soybean oil relying on natural constant low temperature and light-proof conditions,which was a green and safe oil storage technology and worth for promoting the application.