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Effects of Instant Pressure Drop Puffing with Super‐Heated Vapor on the Physical Properties of Granny Smith Apple Chips

An, Fengping, Qiu, Dongzhao, Song, Hongbo, Wu, Xiaoqi, Tong, Jinhua, Guo, Rui
Journal of food process engineering 2015 v.38 no.2 pp. 174-182
apples, color, energy, freeze drying, hardness, heat, puffing, temperature, vapors, water content
A central composite rotatable design of three factors was used to optimize instant pressure drop puffing with super‐heated vapor (IPDPSV) for Granny Smith apple slices. The physical properties of the chips processed by hot‐air drying after IPDPSV, hot‐air drying or freeze drying were analyzed and compared. The results revealed that moisture content, puffing temperature and heating time had significant effects on puffing ratio and color differences. The optimum conditions were 23% moisture content for pre‐dried samples, 122C puffing temperature and 41 s heating time. In these conditions, the puffed slices had a large puffing ratio of 45.137% and a relative small color differences of 4.642. Compared with the chips processed by hot‐air drying or freeze drying, chips processed by hot‐air drying after IPDPSV were brighter in color and had porous structures and suitable hardness. Therefore, IPDPSV is an effective method to improve chips quality. PRACTICAL APPLICATIONS: Instant pressure drop puffing with super‐heated vapor (IPDPSV) could increase the pore volume in Granny Smith apple tissue. The effects of puffing parameters, including moisture content in sample, puffing temperature and heating time, on puffing ratio and color difference were studied. On optimized conditions, Granny Smith apple could be effectively puffed with less color change. IPDPSV combined with hot‐air drying gave the best physical qualities for Granny Smith apple chips, such as color and hardness, compared with traditional hot‐air drying and freeze drying. This processing method spent shorter time than hot‐air drying and consumed less energy than freeze drying. We may reasonably infer that IPDPSV has the advantages of productivity and economy. IPDPSV will be a helpful technology to produce high‐quality Granny Smith apple chips.