Study On Inhibiting Of Coating To Walnut Rancidity

During walnut storage, study on inhibiting of coating to walnut rancidity by analyzing acid value, peroxides value, iodine value, saponification value and sensory evaluation on walnut and husked walnut with coating. So that coating would postphone its storage time.Soy Protein lsolate(SPI) coating was adopted on walnut. The results showed that SP1 coating and package did not influence notability on walnut rancidity, storage temperature did influence notability on walnut rancidity during walnut storage. SPI coating can inhibit walnut rancidity if walnut storaged in 7°C, vacuum shutoff light package.Besides Soy Protein lsolate(SPI) coating was adopted on husked walnut, coating which integrated antioxidant Vc, Cys TBHQ was adopted. The results showed that the effect of inhibition on husked walnut with coating SPI+0.02%TBHQ+0.015%Vc+0.07%Cys coating, SPI+0.02%TBHQ+0.015%Vc coating> SPI+0.07%Cys+0.02%TBHQ coating >SPI+0.015%Vc+0.07%Cys coating > SPI+0.02%TBHQ coating > SPI+0.07%Cys coating >SPI+0.t015%Vc coating > SPI coatingo By analyzing coating with storage and storage temperature, SPI+0.02%TBHQ+0.015%Vc+0.07%Cys coating can inhibit husked walnut rancidityif husked walnut storaged in 7°C, vacuum shutoff light package and its inhibition effect was best.During walnut storage, lipases, lipoxygenases and peroxidases were the main enzymes which affected walnut rancidity. Lipases made the acid value high, and accelerated walnut oil hydrolytic rancidity by hydrolysising oil. Lipoxygenases made the peroxides value arise, and led to oil oxidative rancidity by oxidizing lipids. Peroxidases catalyzed hydroperoxides to break down many small molecules which had off-flavor and promoted oil oxidative rancidity. SPI coating influenced appreciably on three enzymes of walnut and husked walnut, its effect of inhibition to rancidity was not markedly. Coating which contained antioxidant Vc. Cys, TBHQ have marked influence on three enzymes of husked walnut and inhibited its rancidity in evidence. Concerning effect of inhibition to rancidity, the coating compounded with antioxidant Vc, Cys, TBHQ was better than the single.