中红外-热风组合干燥牛肉干降低能耗提高品质

摘要

Drying was the key procedure of jerky processing, different drying methods had different economic benefits and impacts on the quality of jerky. For traditional hot air (HA) drying method has some defects in thermal efficiency, new drying method that combined mid-infrared and hot air (CMIHA) drying was investigated in this paper. CMIHA drying machine was heated directly by mid-infrared without media and convective mode, which significantly increased the rate of energy conversion and energy utilization. The thermal efficiency of CMIHA machine was 70%-80%, and the temperature drift range could be controlled under ±1℃. The structure composition, operational principle and technical characteristics of CMIHA drying machine were introduced in this study. Taking fresh beef as test material, the parameters of CMIHA drying process of jerky was optimized with range analysis, variance analysis and synthesis score analysis. Based on the heat transfer equation of combined radiation and convection, the orthogonal experiments of three factors including drying temperature (50, 60, 70℃), radiation distance (8, 12, 16 cm) and radiation intensity (0.48, 0.64, 0.80 W/cm2) were carried out with the fixed wind velocity (1 m/s) and jerky size. The indices including drying performance and benefit, shear force and color of jerky were measured. According to the range analysis, radiation distance B1 (8 cm) was preliminarily considered as the optimum dryer parameter, but drying temperature (A) and radiation intensity (C) could not be determined. According to the variance analysis, A had significant difference (p<0.1) in drying time, drying energy and b*value and C had no significant difference (p﹥0.1) in all indices, but compared with drying time, L*value and a*value, C had more important impacts on shear force, drying energy and b*value. So as for the low shear force and drying energy-consuming, A3C1 (70℃, 0.48 W/cm2) was preliminarily considered as the optimum drying parameter. Comprehensive analysis of the drying performance and benefit, quality of jerky, the appropriate drying parameter of CMIHA drying machine was A3B1C1. Through synthesis score analysis, A3B1C1 had the highest score among the ten drying parameters. Then the best CMIHA drying process was compared with mid-infrared (MI) drying (drying temperature 70℃, radiation distance 8 cm, radiation intensity 0.48 W/cm2) and HA drying (drying temperature 70℃, heat distance 8 cm, wind velocity 1 m/s), the indices including drying performance and benefit, shear force, texture profiles analysis (TPA), shrinkage rate, acid value and color were measured. The results showed that compared with MI drying and HA drying, CMIHA drying significantly reduced (p<0.05) the drying time and energy, its time-consuming and energy-consuming were only 70%and 90%of that with MI drying, 40%and 22%of that with HA drying. Besides, compared with HA drying, CMIHA drying could significantly increase (p<0.05) springiness, gumminess, chewiness, L*value, a*value, b*value and decrease (p<0.05) shear force and shrinkage rate. Compared with MI drying, CMIHA drying could significantly increase (p<0.05) gumminess, chewiness, L*value and decrease shear force and shrinkage rate, but there were no significant (p﹥0.05) differences in springiness, a*value and b*value. Based on the sensory quality, jerky with CMIHA drying could be easier accepted than that dried by MI drying and HA drying. So, compared with the traditional hot air drying, CMIHA drying could significantly increase economic benefit and quality of jerky. This study can provide a reference for the new drying method of jerky.%为研究中红外-热风组合（combined mid-infrared and hot air，CMIHA）干燥工艺对牛肉干干燥效果的影响，根据红外辐射-对流组合换热控制方程，在风速和物料尺寸固定条件下，分析了干燥温度、辐射距离和辐射强度等因素对干燥性能效益及牛肉干品质的影响，优化了CMIHA干燥工艺参数，与中红外（mid-infrared，MI）干燥、热风（hot air，HA）干燥进行比较，分析了三者在干燥过程中耗时、耗能，及对牛肉干品质的影响。结果表明：CMIHA干燥牛肉干的最佳工艺为干燥温度70℃、辐射距离8 cm、辐射强度0.48 W/cm2，干燥耗时130 min，耗能0.95(kW·h)/kg。此优化工艺的干燥耗时、耗能与MI干燥相比分别降低了30%和10%，与HA相比分别降低了60%和78%，耗时、耗能均显著降低（p＜0.05）；与MI、HA干燥相比，CMIHA干燥牛肉干的黏聚性、咀嚼性、剪切力、收缩率和亮度值L*等指标得到显著改善（p＜0.05）；红度值a*和黄度值b*与MI干燥无显著差异（p＞0.05），但显著高于（p＜0.05）HA干燥；此工艺下牛肉干肉香味浓，质地均匀，色泽呈均匀的亮褐色，总体可接受度显著高于（p＜0.05）MI干燥和HA干燥。与传统热风干燥相比，中红外-热风组合干燥能显著提高经济效益和牛肉干的品质，该研究为开发肉干新型干燥方法提供依据。