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The objective of this work was to determine the effects of infrared radiation combined with heating on grape seeds and oil quality. Experimental results showed that high moisture removal was achieved through infrared radiation heating. After infrared radiation heating for 108 s, the inactivation rates of total aerobic bacterial and total mold-yeast counts of the grape seeds were 1.97 ± 0.12 and 0.62 ± 0.09 log CFU/g, respectively. The maximum microbial reduction was achieved after infrared radiation heating of the grape seeds to 135 ℃ and subsequent holding at 75 ℃ for 60 min. The crude oil yield of samples subjected to these conditions was 10.39%, which was significantly higher ( p < 0.05) than that of the control sample, and their final moisture content was 7.20%. Additionally, increases in the free fatty acid content and peroxide value of the oil were achieved. The iodine value of the oil decreased. In conclusion, surface pasteurization with a high oil yield could be achieved by the combination of infrared radiation heating and the holding process. Consequently, infrared radiation treatment is suggested to be a promising method for the surface pasteurization of grape seeds.

The walnut industry is faced with an urgent need to improve post-harvest processing efficiency, particularly drying and dehulling operations. This research investigated the feasibility of dry-dehulling and infrared (IR) pre-drying of walnuts for improved processing efficiency and dried product quality. Freshly harvested walnuts (ethephon and nonethephon treated) with whole and partly-attached hulls were dehulled using a test device to determine dry-dehulling time and frequency. The physical dimensions of walnuts without, with partly-attached, and with whole hulls were determined. In-shell walnuts of high (43%, w.b.) and low (18%, w.b.) moisture were pre-dried with IR for 2, 3, and 4 min followed by hot air (HA) drying at 43°C for up to 24 h and effects on drying rate and product quality were studied. Based on results, walnuts with whole and partly-attached hulls could be dry-dehulled to achieve over 90% dehulled nut in 45 and 15 s, respectively. Ethephon treatment had no significant influence on dry-dehulling of walnuts with partly-attached hulls. Contrarily, Ethephon-treated walnuts with whole hulls had dehulled nut percentage higher than untreated ones. Walnuts without, with partly-attached, and with whole hulls could be separated based on axial dimensions. IR pre-drying improved walnut drying rate. Up to 7% moisture reduction for high moisture nuts was achievable in 240 s of IR pre-drying with nut center temperature relatively below 43°C in the first 150 s. IR pre-drying for 180 s followed by HA drying had no effect on the quality of processed products compared with HA. The studied approaches have potential to improve processing efficiency and quality of dried walnuts.

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