脉冲超声对灰枣片理化及超声液特性的影响

Effect of Pulsed Ultrasound on Physicochemical Properties of Huizao Tablets and Ultrasonic Liquid Properties

为探究脉冲超声持续时间对枣片理化及超声液特性的影响,以灰枣为原料,设置脉冲超声持续时间为15,30,60 s,并分别于1,2,3,4,5 h对灰枣片和超声液进行取样分析。追踪检测灰枣片的色泽、水分状态、质构和微观结构,以及超声液可溶性固形物(TSS)、色泽、浊度和电导率的变化。结果表明,随着脉冲超声处理时间的延长,灰枣片中的主要水分由结合水转变为自由水,灰枣片组织吸水膨胀,色泽L*值(42.88~50.71)和△E值(3.69~9.85)呈显著增加的趋势,a*值(由19.88降至14.70)和b*值(由22.39降至19.03)呈显著降低的趋势。脉冲超声处理可诱导灰枣片组织内微通道的形成,随着循环次数的增加和脉冲时间的延长,微通道发生扩张,数量增加,同时伴随咀嚼性、弹性和回复性降低。超声液分析结果表明,高强度脉冲持续时间(30 s和60 s)可使灰枣片与超声液在处理前期(1~2 h)发生快速传质,超声液色泽(△E值:0~26.69)、TSS(0~6.1°Brix)、电导率(0~257.54μs/cm)、浊度(0~8.81 NTU)等显著增加,处理后期(3~5 h),15 s处理组超声液特性呈现出最显著的特性变化;至处理完成,各处理组超声液色泽L*值均达到100,a*值与b*值接近于原始状态;同时30 s和60 s处理组超声液中TSS为0°Brix,传质趋于平衡。结论:可根据灰枣片和超声液特性的改变来判断传质的程度,从而适应不同的加工需求。

In order to investigate the effect of pulse ultrasonic(PU)duration on the physicochemical properties of jujube slices and the characteristics of ultrasonic liquid,Huizao was selected as the test materials.Huizao slices were treated by PU with different durations(15,30,60 s)for 5 h,which were sampled and analyzed at 1,2,3,4,5 h,respectively.The color,water status,texture and microstructure of Huizao slices were measured,as well as the total soluble solids(TSS),color,turbidity and conductivity of ultrasonic solution.Results showed that with the increasing in PU time,free water instead of bond water was considered as the most important water for Huizao slice.Huizao was expanded by water adsorption,with a significant increase trend in L*(42.88 to 50.71)and △E(3.69 to 9.85)and a remarkably decrease in a*(19.88 to 14.70)and b*(22.39 to 19.03).The microchannel was produced by the PU,with the increase in processing cycles and pulsed duration,the microchannel became bigger and more,accompanied with the decreased chewiness,springiness and resilience.It was found that in the initial phase(1-2 h)the color(△E:0-26.69),total soluble solids(TSS,0-6.1°Brix),conductivity(0-257.54μs/cm)and turbidity(0-8.81 NTU)gradually decreased because of the fast mass transfer resulted from the PU with long duration(30 s and 60 s).In the later phase(3-5 h),the most obvious changes were shown in 15 s group.At the end,all the L*values were 100,while a*vales and b*values were approached to the initial phase of ultrasonic solution.Along with the transfer balance,the TSS in the 30 s and 60 s group was 0°Brix.Therefore,the degree of mass transfer could be evaluated by the changes in characteristics of Huizao slices and ultrasonic solution,which could adapt to different needs in the food industry.