真空微波和冻干组合降低胡萝卜片的干燥能耗

为减少脱水蔬菜冷冻干燥过程的能耗,以胡萝卜片为试材,采用真空微波和冷冻干燥组合的工艺,即先微波真空后冻干（组合Ⅰ）和先冻干后微波真空干燥（组合Ⅱ）。组合Ⅰ的优化参数为：真空微波阶段微波功率密度1.6w/g,脱去40个百分点的湿基水,冻干阶段升华干燥4 h,解析干燥3 h;组合Ⅱ的优化参数为：冻干阶段升华干燥7 h;真空微波干燥功率密度选1.0w/g以下,采用温度控制模式。所干燥胡萝卜片的β-胡萝卜素保留率和复水率等与纯冻干产品接近,体积保留率比纯冻干稍小,但仍能保持平直的外形;两种组合干燥工艺比纯冻干分别节能47.0%和54.2%,且干燥时间可缩短一半。     

鲜切莲藕微生物模型的建立及货架寿命预测

研究鲜切莲藕在不同贮藏温度下细菌生长趋势和感官质量的变化,建立微生物生长模型,预测鲜切莲藕的货架寿命;将莲藕切片经保鲜处理、包装后,置4、8和20℃贮藏温度下贮藏,测定贮藏期间鲜切莲藕中细菌总数,利用DPS软件,建立Gompertz模型;结果表明,试验中所建立的Gompertz模型能有效地拟合在不同贮藏温度下鲜切莲藕中细菌总数的动态变化;建立的微生物模型能预测不同贮藏温度下、不同贮藏时间内鲜切莲藕中的细菌总数,为快速、有效地评估鲜切莲藕的货架寿命和微生物安全性,提供了一个方便有效的方法。     

超声对橡木陈酿白兰地促溶工艺的优化

为了优化橡木中单宁类物质的溶出工艺,以50％Vol新蒸馏白兰地为试验原料,采用超声波非热力加工技术,通过单因素试验研究了超声时间、超声功率、橡木添加量、浸泡时间对白兰地中色度、总酚、单宁、pH值、总酸、总酯、感官评价的影响,结合Box-Behnken响应面法优化超声促溶橡木中单宁物质的溶出工艺.结果表明,超声促溶的最佳工艺条件为:超声时间11 min,超声功率180 W,橡木添加量1.20 g/100 mL,浸泡时间20 d,该条件下单宁含量为1319.42 mg/L.     

包装形式和贮藏条件对柠檬冻干片在贮藏过程中色泽变化的影响

[目的]寻求适用于柠檬冻干片的包装材质及其合适的贮藏条件。[方法]以真空冷冻干燥方法加工出的柠檬干片为试材,探讨不同包装形式和不同贮藏条件对柠檬冻干片色泽变化的影响。[结果]贮藏温度、氧气和光照均会令柠檬冻干片产生不同程度的褐变,且贮藏温度对柠檬冻干片的色泽变化影响最大,其次是氧气,再次是光照强度。[结论]选择避光、脱氧包装并于低温条件贮藏更利于柠檬冻干片的色泽保持。     

青苹果片过热蒸汽瞬时压降膨化动力研究

针对过热蒸汽瞬时压降膨化动力不明晰、膨化程度调控困难的问题,建立了片状物料膨化动力通用数学模型,表明膨化的能量源自于物料内部过热液体闪急蒸发做功和过热蒸汽瞬时释放做功2部分。由于不同含水率的待膨化样品孔隙率不同,而且膨化前过蒸汽加热过程中热交换所产生的冷凝水质量也不同,从而膨化前样品的孔隙率产生了不同的变化。因此,膨化度与物料的含水率、孔隙度有关,也与过热蒸汽的状态有关。以青苹果片为试验材料,结果表明待膨化样品的孔隙率随着含水率的增大而明显减小。采用温度和压力分别为430~470 K和0.1~0.5 MPa、过热蒸汽膨化含水率为15%~35%的青苹果片,运用建立的膨化动力模型可有效地预测和评价膨化条件与膨化度的关系(R~20.89)。增大蒸汽压力,对冷凝水的影响不大,可增大过热液体和过热蒸汽做功,对提升膨化动力和膨化效果最明显;升高过热蒸汽温度仅能提高过热液体做功,但显著增大的冷凝水量使得过热蒸汽做功减小,对提高膨化动力及膨化效果不明显;增加物料的含水率明显地增大过热液体做功,但是由于冷凝水量明显增加而降低了过热蒸汽做功,总体上表现为较大程度增大了膨化动力和膨化度。     

油炸藕片含油量快速预测及微观结构的三维重建

以油炸藕片为研究对象,首先利用高光谱图像技术(hyperspectral imaging technology,HSIT)结合联合区间偏最小二乘(synergy interval partial least squares,si PLS)和净分析物法(net analyze signal,NAS)提取油炸藕片的光谱信息,建立快速预测模型,并计算每个像素点的油含量值,将其表面油分布可视化;然后利用激光共聚焦显微镜(confocal laser scanning microscopy,CLSM)观察油在细胞中的分布,并扫描藕片Z轴方向序列图片进行微观结构的三维重建。结果显示,优选4个子区间,依据NAS法挖掘同油相关的NAS信号NAsk,建模后其预测集相关系数和均方根误差分别为0.819和0.682 mg/g,表明HSIT可快速预测油炸藕片含油量并可视化表面油分布。经CLSM扫描并图像三维重建后观察,油主要分布在细胞表面、边缘、细胞间隙以及破碎细胞内,且细胞的形状、大小均发生了很大的变化,可观察其内部油分布。结果表明,该研究可为油分布提供有效手段,并依据微观结构的变化为减少含油量提供科学的理论依据。     

薄片丝掺配·片掺配模式下细支卷烟品质稳定性比较

[目的]提升细支卷烟品质。[方法]运用方差分析,从加工过程稳定性、混合均匀度、物理指标稳定性、主流烟气以及感官评价5个方面,对比薄片丝掺配和片掺配2种模式下的细支卷烟样品。[结果]薄片丝掺配加工过程稳定性较优;薄片丝掺配混合均匀度高于薄片片掺配;薄片丝掺配较薄片片掺配样品,端部落丝量小、吸阻和密度有更高稳定性;薄片丝掺配降低烟碱和CO的作用较薄片片掺配有显著提高,且焦油、烟碱、CO等各项烟气指标更稳定;薄片丝掺配样品的香气、杂气、刺激性、余味指标较优,总体质量优于薄片片掺配样品。[结论]对于提高细支卷烟的品质稳定性,薄片离线加工后丝掺配方式比传统薄片叶掺配模式更优。     

Suitability of aqueous chlorine dioxide versus sodium hypochlorite as an effective sanitizer for preserving quality of fresh-cut lettuce while avoiding by-product formation

Aqueous chlorine dioxide (ClO₂) has been postulated as an alternative to sodium hypochlorite (NaClO) for fresh-cut produce sanitization with the advantage of avoiding the risks associated with chlorination by-products. However, little is known about its influence on preserving quality and the potential formation of trihalomethanes (THMs) under typical processing conditions. The suitability of aqueous chlorine dioxide (3 mg L⁻¹) as an effective sanitizer of fresh-cut iceberg lettuce stored under active modified atmosphere packaging (MAP) at refrigerated conditions was determined and compared with sodium hypochlorite (100 mg L⁻¹). Fresh-cut lettuce washed with tap water was used as a control. The epiphytic microbiota were characterized by the evaluation of the major relevant microbial groups such as mesophiles, psychrophiles, Pseudomonas spp., Enterobacteriaceae, lactic acid bacteria, yeasts and moulds. Additionally, gas composition, sensory quality, vitamin C and individual and total phenolics were monitored after washing and during storage for 3 d at 4 °C followed by 7 d at 8 °C. In general, the natural microbiota of fresh-cut lettuce after washing and storage was equally affected by the different washing solutions, with the exception of yeasts which showed the highest growth after 10 d storage in samples washed with chlorine dioxide. None of the tested washings negatively affected sensory quality, which was acceptable after 10 d storage. Additionally, the content of bioactive compounds was not significantly affected either by washing solution or by storage time. The potential formation of THMs was evaluated by the analysis of lettuce washed in water with a chemical oxygen demand (COD) of 700 mg L⁻¹ treated for 30 min with sodium hypochlorite (100 mg L⁻¹) or chlorine dioxide (3.7 mg L⁻¹). Trihalomethane formation was only detected in the process water in which sodium hypochlorite was applied (217 ± 38 μg L⁻¹). However, THMs formation in fresh-cut lettuce was negligible despite the sanitation procedure. The formation of THMs was only detected in fresh-cut lettuce when sodium hypochlorite was used under very extreme conditions where lettuce was washed in water with a high level of organic matter (COD = 1800 mg L⁻¹), high sodium hypochlorite concentration (700 mg L⁻¹) and long contact time (60 min). Our data suggest that aqueous chlorine dioxide is as suitable as sodium hypochlorite for fresh-cut lettuce sanitation with the advantage of preventing the formation of THMs.     

硕桦小径木圆截片常规干燥工艺初探

该文研究了硕桦小径木圆截片试样的干燥技术,制定了可行的常规干燥基准．试验结果表明,小径木圆截片在干燥过程中易产生径裂,其主要原因是弦径向干缩不一致引起的．热湿处理能提高干燥速度,树皮的有无对开裂影响不大．初步提出了硕桦小径木圆截片的部分干燥质量指标．     

不同热风干燥温度对高良姜片品质特性的影响

为明确热风干燥温度对高良姜片品质特性的影响,以高良姜为原料,分别对60、70、80、90 ℃条件下干燥获得的高良姜片的干燥时间、色泽、总酚、总黄酮和挥发性成分进行了比较分析.结果表明:高良姜片的干燥时间随温度升高而减小,60℃时干燥时间为29h,90℃时缩短为11h;高良姜片L*值随温度的升高而增大,a*值和b*值则整...