Study On Storage Stability Of Linseed Oil

Linseed oil is a high nutritional and functional vegetable oil, with unsaturated fatty acid content of more than 87% and n-3 fatty acid ?-linolenic acid content as high as 40% to 60%, much higher than the walnut oil, camellia oil, olive oil and other healthy fats, known as "fish oil on the prairie". However, linseed oil is prone to get oxidative rancidity, in order to ensure its good eating quality, systematic study of their storage performance is needed to acquire proper storage methods. Up to now, studies on flaxseed oil storage have been reported but are still lack of systematicness.This article discussed the changes in linseed oil quality during storage. Taking peroxide value, K232 value, acid value, K270 value and TBA value as quality indicators, the influence of pretreatment process, extraction method, storage conditions and nutritional components were studied and the oxidation kinetics model was constructed to predict the shelf life of linseed oil at different temperatures, aiming to provide scientific basis for the production and storage of linseed oil. The results are as follows:(1) Influence of different pretreatments on the storage stability of flaxseed oilThe quality and storage performance of linseed oil pretreated respectively by baking, roasting and microwaving after 135 d of storage under room temperature were compared. The results showed that microwave pretreatment could improve the storage stability of linseed oil, while baking pretreatment showed slight influence and roasting pretreatment showed the worst. The contents of nutrition such as polyphenols, flavonoids and sterols kept declining during the storage process, which showed a negative correlation to the physicochemical indexes.(2) Effect of different extraction methods on the storage stability of flaxseed oilThe storage stability of linseed oil obtained by solvent extraction, crushing and subcritical extraction were studied. The results showed that the best extraction method was subcritical liquid extraction, followed by pressing and then extracting. In consideration of cost and actual production demand, the press method is more adoptable in that the oxidation stability of press oil is close to subcritical extraction oil.(3) Effect of different storage conditions on the storage stability of flaxseed oilTaking press linseed oil as raw material, peroxide value, K232 value, acid value, K270 value and TBA value as quality indicators, the influence of defferent temperatures, light conditions, oxygen content, container material and color of the package bottle on the storage properties of linseed oil were studied. The results showed that temperature was the most influencing factor and low-temperature storage was more suitable. The indexes under dark conditions were better than fluorescent, natural light. The storage properties of sealed storage were better than that of open storage. Among ceramic bottle, glass bottle and PET bottle, ceramic bottle was the best, followed by glass bottle and the last was PET bottle. The storage stability were in colored bottle better than transparent bottle, among which green and red color showed the best storage properties to delay linseed oil oxidation effectively.(4) Quality change analysis during storageDetermination of changes in moisture and volatile matter, iodine value, refractive index and fatty acid composition of linseed oil during storage was completed. The changes of moisture and volatile matter, iodine value were not significant while there was an increase in refractive index and no severe reverse color phenomenon. The composition of fatty acid did not change significantly, the fatty acid content after storage of 0 d,90 d,150 d were respectively 89.31%,89.22% and 86.23%.Principal component analysis method was adopted to study the relative importance of different physicochemical on the storage properties of linseed oil. The results showed that POV value, TBA value, K270 value, acid value and K232 value the oxidation condition could largely reflecte the oxidation condition and explain the most information of quality changes during the oxidation.(5) Shelf life prediction of linseed oilBased on linseed oil peroxide value changes at different temperatures, linseed oil oxidation kinetics was consistent with first-order oxidation reaction, the relevant rate constants was obtained by Arrhennius formula, and the shelf life model of linseed oil was Based on the model, the shelf life was under 20?,25?,30? was predicted. It was proved that the error of the model was within 10%, and could predict the shelf life effectively within 50? (6) Influence of antioxidants on storage stability of flaxseed oil The results indicated that all the antioxidant both showed certain effects on delayingThe oxidation. What's more, the synergists could enhance the effect of antioxidant. The complex optimization results showed that 0.005%TBHQ+0.01% tea polyphenol+0.02%CA+0.01%VC was a good combination for anti-oxidation with the least addition amount of antioxidant, thus makes the oil product more healthy and safe.