Effects of various pretreatments and drying methods on Salmonella resistance and physical properties of cabbage

The combined effects of pretreatment and drying methods on the resistance of Salmonella attached to vegetable surfaces as well as some physical properties, in terms of color and shrinkage, were investigated. Cabbage was used as a test vegetable and Salmonella Anatum was used as a test microorganism. Cabbage leaves were pretreated either by soaking in 0.5% (v/v) acetic acid for 5 min, blanching in hot water for 4 min or blanching with saturated steam for 2 min prior to either hot air drying, vacuum drying (10 kPa) or low-pressure superheated steam drying (10 kPa) at 60 °C. Based on an initial Salmonella contamination level of approximately 6.4 log CFU/g, soaking in acetic acid, hot-water and steam blanching resulted in 1.6, 3.8 and 3.6 log CFU/g reduction in the number of Salmonella, respectively. Drying without pretreatment could not completely eliminate Salmonella attached on the cabbage surfaces, while no Salmonella was detected on the pretreated samples at the end of the drying process. Volumetric shrinkage was not affected by the pretreatment and drying methods. Dried blanched samples exhibited greener and darker color than the dried acetic acid pretreated and untreated samples.     

扇贝柱预处理工艺优化及干燥过程中品质变化评价

以栉孔扇贝柱为实验对象对其干燥前预处理工艺进行优化,得出最佳预处理工艺参数组合,对经过优化工艺预处理后的样品在干燥过程中外形、营养成分、流变学特性参数的变化进行评价。结果表明:栉孔扇贝柱干燥前预处理工艺参数组合为:扇贝柱在瓜儿豆胶和黄原胶的复配液中浸渍时间为1 h,复煮时间为1 min。在干燥过程中,工艺优化组扇贝柱样品水分含量变化缓和,扇贝柱干品柱形完好,表面裂纹细且少,不出现凹陷和散柱现象,外形评分较高。与传统预处理工艺相比,优化后的工艺预处理扇贝柱基本成分含量较高,营养成分损失少;流变学特性参数中硬度变化小而弹性、黏聚性和咀嚼性均显示出增长趋势,反映其具有弹性大、硬度小、黏结性好的特点,也说明改良的预处理工艺条件具有可行性。      

预处理对气流膨化干燥黄桃丁品质的影响

为了研究预处理对黄桃气流膨化干燥的影响,探讨了成熟度、桃丁厚度、烫漂、糖浸渍、冻融和干燥时间对黄桃脆丁产品膨化度、色泽和质构的影响。研究结果表明:成熟度对黄桃脆丁产品的色泽和质构影响较大;烫漂2~3 min可改善黄桃组织结构,提高膨化效果;糖浸渍使黄桃脆丁产品酸甜可口,组织内部充实,利于膨化骨架形成,对产品色泽具有保护作用;冻融可改善产品硬度和色泽,提高品质;预干燥时间对气流膨化的膨化效果和形状保持能力具有重要影响。较适宜的预处理条件为:九成熟的黄桃原料,桃丁厚度2 cm,烫漂2~3 min,糖浸渍浓度6%,冻融1次,预干燥2.5 h。为黄桃干制品产业化生产提供技术支撑。      

预处理方式对热风干燥玫瑰花瓣品质特性的影响

采用5%柠檬酸溶液、20%糖溶液、20%NaCl和柠檬酸混合溶液浸渍、烫漂4种处理方式处理玫瑰花瓣,以未预处理的花瓣作为对照,进行热风干燥对比试验和分析,对花瓣品质特性(色泽、总黄酮含量、总酚含量)以及微观结构等进行比较,并结合模糊数学综合评判法进行感官评定。结果表明:预处理方式对玫瑰花瓣的干燥速率有显著影响,且在含水率较高时尤其明显;微观结构有一定的差异性。其中,5%柠檬酸溶液组耗时最长,ΔE最小;20%糖溶液组复水比最低;混合溶液组色泽变化ΔE最大,总酚含量最高;烫漂组耗时最短,总黄酮含量和复水比最高。经烫漂预处理后的花瓣干燥后得到的感官评分值最高,对应的干燥时间、ΔE、复水比、总黄酮含量及总酚含量分别为120min、18.17±0.54、3.01、0.27mg/g、1.43mg/g。因此,采用烫漂预作为预处理方式可以提高食用玫瑰花瓣干制品的品质。     

Comparative study of different combined superheated-steam drying techniques for chicken meat

The purpose of this study was to compare and evaluate different drying techniques for chicken meat, which was aimed as an ingredient for ready-to-eat noodle. Two multi-stage drying techniques, i.e., superheated steam drying in the first stage followed by heat pump drying in the second stage (SSD/HP), and superheated steam drying in the first stage followed by hot air drying in the second stage (SSD/AD), were proposed. The effects of superheated steam temperature and moisture content of chicken at the end of the first-stage drying on the drying kinetics and quality of the dried product viz. color, shrinkage, rehydration ability were then evaluated. The results were also compared with those of purely superheated steam drying. SSD/HP was found to be the most suitable drying method for drying chicken as an ingredient for ready-to-eat noodle.     

超声和烫漂预处理对红薯叶热风干燥的影响

采用超声、烫漂两种方式对红薯叶进行热风干燥前的预处理,研究超声时间、超声功率、超声温度和烫漂时间、烫漂液ZnAc_2与EDTA-2Na质量比、烫漂温度对红薯叶热风干燥后叶绿素、复水性、色差、干燥特性、能耗以及微观结构的影响。结果表明:超声处理的最佳工艺为超声时间10min、超声功率300W、超声温度40℃,经超声预处理的红薯叶干燥效率较高,皱缩率低,组织结构较为完整;烫漂处理的最佳工艺为烫漂时间60s、烫漂液ZnAc_2与EDTA-2Na质量比2:1、烫漂温度80℃,经护色液烫漂处理干燥后的红薯叶复水率、叶绿素含量和色泽都稍高,质构紧密均匀,细胞开孔率高,总能耗低。     

预处理和干燥方式对方便米饭品质的影响

研究不同蒸煮方式、干燥方式和预处理方式对方便米饭质构、体外消化率、血糖指数等因素的影响。实验结果表明,电饭锅蒸煮制备的方便米饭硬度和黏度要高于常规制备的方便米饭。-20℃冷冻+80℃热风干燥和4℃水洗+-20℃冷冻干燥方式制备的方便米饭品质最接近新鲜米饭。热风干燥方便米饭的复水率为2. 71,复水时间为8 min;冷冻干燥方便米饭的复水率为3. 32,复水时间为5 min。2种干燥方式制备的方便米饭体外消化率均高于新鲜制备的米饭,其饱和浓度C∞、水解指数HI和血糖指数GI等指标也相应的增高。感官评价结果表明,2种干燥方式制备的方便米饭均具有较好的品质,口感良好;其中,4℃水洗+-20℃冷冻干燥制备的方便米饭感官评价更高。     

高密度CO2预处理对樱桃番茄干燥的影响

将樱桃番茄经过和未经过高密度CO2(DPCD)预处理,然后进行热风干燥,以比较干燥速率和干燥后产品品质的变化,探索新型干燥工艺。结果发现,经过1、2和3MPaDPCD处理组与对照组相比,干燥速率提高,干燥时间缩短,产品收缩率降低,复水率提高,褐变度没有显著变化;但经高压处理的干燥产品VC和颜色比对照组差。综合各指标分析,除了VC和颜色,DPCD预处理后的干燥指标优于对照组。     

Effect of drying temperature on polyphenolic content and antioxidant activity of apricots

This study was carried out in order to check for the influence of drying parameters on the phenolic compounds and antioxidant activity on two apricot cultivars (Pelese and Cafona) using two sets of air drying temperatures: (1) air temperature at 55 °C; (2) air temperature at 75 °C. Whole fresh and dried fruits were assessed for: phenolics, ascorbic acid, antioxidant activity and redox potential (all parameters were calculated on a dry matter basis). Analysis of data shows that the decrease in chlorogenic and neochlorogenic acid in Cafona cultivar is higher at the lower drying temperature. Catechin showed the same behaviour of hydroxycinnamic acids in both cultivars, while the decrease in the other compounds was significantly more marked in the sample dried at 75 °C. The antioxidant activity increased significantly in Cafona fruits and this increase was confirmed by a diminution of the redox potential.     

Effect of blanching on microwave freeze drying of stem lettuce cubes in a circular conduit drying chamber

Effects of boiling water and microwave blanching methods on the dielectric properties, electrical conductivity as well as microstructure of stem lettuce cubes (as a model for plant tissue) were studied. The study also focused on how different blanching methods affect microwave freeze-drying (MFD) in a circular conduit drying chamber and conventional freeze drying (FD) of stem lettuce cubes. Results showed that the electrical conductivity of samples blanched by microwave was two times higher than that of boiling water blanched ones and five times higher than that of unblanched samples. Apart from that, dielectric constant (ε′) and loss factor (ε″) of the stem lettuce cubes decreased significantly after freezing. MFD duration of microwave blanched samples was approximately 4.5 h, reduced by 30% compared to boiling water blanched ones. MFD process in a circular conduit yielded products of high quality compared to that in a tray.     

Influences of hot air drying and microwave drying on nutritional and odorous properties of grass carp (Ctenopharyngodon idellus) fillets

Hot air drying and microwave drying were applied to dry fish fillets made of grass carp (Ctenopharyngodon idellus), and the correlative influences on nutritional and odorous properties were evaluated by proximate composition, protein solubility, amino acid composition, fatty acid composition, peroxide value, anisidine value, and odour evaluation. Drying resulted in a significant increase of protein but reduced fat content. There was lack of negative influence of the drying process on the amino acid composition of grass carp fillets. Both saturated and monounsaturated fatty acid contents decreased, while polyunsaturated fatty acids increased by an average of 23.8% after drying. Microwave-dried samples showed lower fat loss, higher protein solubility, and lower anisidine values than hot air-dried samples. There was no significant difference in odour quality between hot air-dried and microwave-dried samples. The present study provides a possible application of microwave drying as an efficient drying process for fish fillets.     

不同干燥方法对南美白对虾品质的影响

干燥方法对南美白对虾品质具有重要影响。本文研究了热风干燥、冷风干燥、微波真空干燥3种干燥方法对南美白对虾色泽、虾青素含量、组织结构、质构和感官质量的影响。结果发现:干燥后L*下降,其大小依次为微波真空干燥>冷风干燥>热风干燥;虾青素含量降低,微波真空干燥产品虾青素含量最高,为77.5μg/g;热风干燥后肌纤维断裂严重,而冷风干燥和微波真空干燥产品肌纤维结构较为完整;干燥后南美白对虾硬度、胶着性、咀嚼性提高,其中微波真空干燥产品增加最为显著;感官方面,微波真空干燥产品口感风味更好。综合来看,微波真空干燥方法较为理想。      

干燥方式对大果山楂粉干燥速率及品质的影响

探究真空微波脉冲干燥、真空微波干燥、热风联合真空微波干燥和热风干燥4种干燥方式对大果山楂粉色泽、褐变度、持水性、持油性、透光性、Vc、总酸和黄酮含量等品质指标的影响。结果表明:干燥方式对大果山楂粉的色泽、褐变度、透光性和总酸含量有显著影响(P0.05);真空微波脉冲干燥大果山楂粉的综合品质优于其他3种,该工艺生产效率较高,成本低,是大果山楂粉生产中较适宜的干燥工艺。     

前处理和干燥对甘薯全粉品质影响的研究进展

本文从甘薯全粉生产过程中的前处理和干燥两个方面对甘薯全粉品质的影响进行综述,对现代食品技术在生产甘薯全粉中存在的问题进行了探讨,以期为该领域的研究者提供理论参考.     

干燥条件对熟化竹荪品质的影响

为了选出对熟化竹荪干制品最好的干燥方式及干燥温度,以熟化的竹荪为原料,比较热风干燥、真空干燥、远红外干燥和真空冷冻干燥4种干燥方式在不同的干燥温度条件下对熟化竹荪干制品色泽、复水性、质构、多糖含量及组织结构的影响。结果表明,真空冷冻干燥和真空干燥能使竹荪干制品分别在20,30min达到完全复水,而热风干燥和远红外干燥均需要40min才能完全复水。真空冷冻干燥和真空干燥的整体色泽#E值明显低于热风干燥和远红外干燥,其中真空冷冻干燥在20℃条件下干燥的竹荪干制品#E值最小为3.021。真空冷冻干燥和真空干燥均使竹荪干制品的硬度和咀嚼性小于热风干燥和远红外干燥,但对弹性影响不大。真空冷冻干燥能基本保持竹荪原有的组织结构且制品的多糖含量显著高于其他三种干燥方式。综合试验结果,真空冷冻干燥和真空干燥方式均能较好地保持熟化竹荪干制品品质。     

干燥工艺对红茶品质的影响

以碧香早夏秋季一芽二叶为原料,在萎凋、揉捻、发酵等红茶加工工艺基础上,将箱式热风、锅炒、链式热风、平板式热风和微波5种干燥方式的不同组合分别应用于毛火初干与足火复干工艺中,从感官品质、滋味品质成分和香气品质成分3个方面探讨了不同干燥工艺对红茶品质的影响。结果表明,与箱式热风初干及复干工艺加工的对照茶样相比,采用120 ℃链式热风初干和120 ℃锅炒复干工艺的红茶品质较好,汤色红橙亮,香气甜香带花香,滋味较醇爽;茶黄素、茶红素、水浸出物、可溶性糖、简单儿茶素、酯型儿茶素和总儿茶素质量分数显著增加（P<0.05）,茶多酚、咖啡碱质量分数以及酯型儿茶素/总儿茶素的比值显著降低（P<0.05）;醇类香气物质相对质量分数增加9.68%,同时增加了苯甲醇（苹果香）、7-甲基-3-亚甲基-6-辛-1-醇（花香）、异香叶醇（玫瑰香）、植物醇（花香）、2,6,6-三甲基-1-环己烯-1-乙醛（木香、玫瑰香）、2-（5-甲基-5-乙烯基四氢呋喃-2-基）丙-2-基碳酸乙酯和水杨酸甲酯（薄荷香味）等香气成分,而顺-α,α-5-三甲基-5-乙烯基四氢化呋喃-2-甲醇（带樟脑气息）、辛烯醛（略带刺鼻）、壬酸（腐臭味）等不良香气成分减少。由此提示链式热风毛火初干和炒锅足火复干相结合的干燥工艺技术有利于红茶品质的提高。     

不同干燥条件对张溪香芋全粉品质的影响

以张溪香芋为原料,经去皮切片蒸煮,采用日晒(约35℃)、不同温度(60℃、70℃和100℃)热风干燥四种不同干燥条件进行干燥,以干燥后粉碎所得的香芋全粉的色泽、水分、吸水性、吸油性、含糖量、蛋白质含量和颗粒分散性为指标,研究了不同干燥条件对张溪香芋全粉品质的影响。结果表明采用60℃低温热风干燥得到的张溪香芋全粉综合品质最佳,全粉色泽较浅偏白色,颗粒粒径均匀,分散性好,营养成分含量较高,具有较好的吸水性和吸油性。     

油莎豆热风干燥特性及数学模型研究

以新鲜油莎豆为原料,研究风温和风速对油莎豆热风干燥特性的影响,计算干燥过程中有效扩散系数与活化能,并选取8种干燥动力学模型进行拟合分析。实验结果表明：热风温度越高,干燥速率越快,干燥时间越短;风速对干燥速率影响较小。本试验干燥过程主要发生在降速阶段,油莎豆有效水分扩散系数2.2856×10^-10～7.8112×10^-10,平均活化能为35.31kJ/mol,Two-term模型可以很好的反映油莎豆热风干燥过程,实验值与预测值吻合度较高,拟合效果良好。