红外漂烫联合热风干燥对核桃仁的品质与贮藏稳定性的影响

Effects of infrared radiation blanching combined with hot-air drying on the qualities and storage stabilities of Juglans regia L. kernels

中文关键词:  核桃仁  热风干燥  红外漂烫  内源酶  贮藏稳定性

英文关键词:Juglans regia L. kernels  hot-air drying  infrared radiation blanching  endogenous enzyme  storage stability

中文摘要:

      目的 探究红外漂烫(infrared radiation blanching, IR)联合热风干燥(hot-air drying, HA)对核桃仁的品质与贮藏稳定性的影响。方法 分别采用500、600、700 W功率对核桃仁进行IR处理, 随后分别用60、70、80℃热风进行HA, 再分析IR联合HA (IR-HA)的核桃仁的含水量、干燥速率、色泽、过氧化值(peroxide value, POV)、酸价(acid value, AV)、单宁和总酚含量、抗氧化活性、内源酶活性以及贮藏稳定性。结果 500 W需IR 120 s, 600 W需65 s, 700 W需45 s可使核桃仁的中心温度达到90℃; IR-HA相比HA对照组(control group-HA, CK-HA)具有更快的干燥速率, 色泽变化更小(ΔE<6.00), POV和AV更低, 单宁含量在40.00 μg/g以下, 总酚和抗氧化能力提高到50%以上, 残余酶活力最低可在10%以下。在35℃、30%相对湿度条件下贮藏30 d, 核桃仁的内源酶活性均逐渐下降, 而POV和游离脂肪酸含量逐渐上升, 但与CK-HA相比, IR-HA显示了更弱的脂氧合酶、过氧化物酶和脂肪酶活力, 更低的POV及游离脂肪酸含量, 以及更稳定的脂肪酸组成。结论 600 W IR 65 s接着60℃ HA的加工工艺提高了核桃仁的干燥效率, 提升了核桃仁的营养品质和贮藏稳定性。

英文摘要:

      Objective To investigate the effects of infrared radiation blanching (IR) combined with hot-air drying (HA) on the quality and storage stability of Juglans regia L. kernels. Methods The Juglans regia L. kernels were blanched with infrared radiation at 500, 600 and 700 W power, respectively, and then dried with hot-air at 60, 70 and 80℃. Then, the moisture content, drying rate, color, peroxide value (POV), acid value (AV), content of tannin and total phenolics, antioxidant activity, endogenous enzyme activity and storage stability of Juglans regia L. kernels by IR-HA were analyzed. Results The 500 W requires 120 seconds of IR, 600 W requires 65 seconds, and 700 W requires 45 seconds to achieve a center temperature of 90 ℃ Juglans regia L. kernels; compared to control group-HA (CK-HA), IR-HA had a faster drying rate and less color change (ΔE<6.00), lower POV and AV, with a tannin content of 40.00 μg/g, the total phenols and antioxidant capacity increased to over 50%, and the minimum residual enzyme activity could be below 10%. Stored at 35℃ and 30% relative humidity for 30 days, the activities of endogenous enzymes of Juglans regia L. kernels gradually decreased, while the POV and free fatty acid content gradually increased. However, compared with CK-HA, IR-HA showed weaker activities of lipoxygenase, peroxidase and lipase, lower POV and more stable fatty acid composition. Conclusion The technology of blanching with 600 W IR for 65 s followed by HA at 60℃ can improve the drying efficiency, nutritional quality and storage stability of Juglans regia L. kernels.