影响荔枝酒发酵过程中挥发酸的因素

挥发酸的控制是荔枝酒的生产过程中的重要技术瓶颈,发酵过程易造成荔枝果酒挥     

Effect of Calcium Lactate, 4-Hexyl Resorcinol and Vacuum Packing on Physico-chemical, Sensory and Microbiological Qualities of Minimally Processed Litchi (Litchi chinensis Sonn.)

Litchi (Litchi chinensis Sonn.) fruits are very susceptible to pericarp browning which adversely affects consumer acceptability even though the aril portion remains in excellent condition. Litchi arils (litchis) were treated with a solution containing 0–2% (w/v) calcium lactate (CL), 0–0.02% (w/v) 4‐hexyl resorcinol (4‐HR) and 1% potassium sorbate. The pH of solution was adjusted to 4.0 with citric acid. Treated litchis were packed in polystyrene trays, over‐wrapped with polypropylene film, vacuum‐packed (0, 47409.3, 94831.9 Pa) and stored at 4 ± 2 °C. Drip losses, pH, total soluble solids (TSS), sensory attributes and microbiological quality of stored samples were estimated. A four‐factor, three‐level experimental design (D₆ Hokes design) with 19 experiments was chosen. Mathematical models were developed to analyse and predict the effect of CL, 4‐HR, in‐package vacuum and storage time on the responses. TSS, pH and sensory scores decreased significantly (P 0.01), whereas drip losses and microbial count increased significantly (P 0.01) with time. Drip loss was significantly (P 0.1) reduced by addition of CL. 4‐HR prevented browning and changes in colour score during storage were significantly less. Vacuum in packages exerted significant (P 0.01) effect over pH, TSS, sensory and microbiological qualities of minimally processed litchis.     

基于人性化理念的荔枝剥皮器设计

目的为解决手剥荔枝不卫生和易弄伤指甲等问题,设计一款供日常食用荔枝使用的剥皮器。方法分析荔枝的物理特性和常用的荔枝剥皮方法,根据人性化设计理念中的人机工程学因素和美学因素综合进行设计:依据人手尺寸确定剥皮器手柄的造型与尺寸,根据荔枝物理特性确定刀刃的尺寸,设计并进行实验确定刀刃的锋利程度及手柄与刀刃的厚度;根据美学因素完善造型,确定3种色彩计划。结论得到了较理想的、能满足日常使用需求的荔枝剥皮器。     

荔枝保鲜的研究

在低温下 ,对不同时期的贮藏荔枝的酸度和含糖量进行了测定 ,对比了不同贮藏方法下 ,荔枝内部发生的变化     

银杏叶粗提物对荔枝的防腐保鲜效果

以银杏为研究对象,利用乙醇浸提法得到银杏叶粗提物,从色泽、VC含量、质量损失率、菌落总数以及感官评定等方面评价银杏叶粗提物对荔枝的防腐保鲜效果。结果表明:随着处理时间的延长,银杏叶粗提物能减少荔枝水分损失,抑制褐变,延缓VC含量的下降,减少微生物对荔枝果肉的侵染以及降低腐烂率,较好地保持了荔枝的感官品质。在试验浓度范围内(0.2%~0.6%),银杏叶粗提物浓度与荔枝防腐保鲜效果呈正相关。银杏叶粗提物对荔枝具有较好的防腐保鲜效果。     

Effects of Four Different Drying Methods on the Quality Characteristics of Peeled Litchis (Litchi chinensis Sonn.)

Four different drying methods, namely, air drying (AD), microwave-assisted vacuum drying (MWVD), coupled microwave–hot air drying (MWAD), and freeze drying (FD), were studied, in terms of drying time, color, reducing sugar content, shrinkage, microstructure, and sensory evaluation. The drying rate of MWVD and MWAD were notably faster than that of AD and FD. The highest reducing sugar content was observed in MWAD, followed by MWVD. No significant differences were observed in reducing sugar between air-dried and freeze-dried products. FD had the best color and shrinkage among the other drying methods. The color and shrinkage of MWVD drying is close to the fresh litchis and much better than hot air and MWAD. Scanning electron microscopy (SEM) images showed that the MWVD and FD litchis have a porous structure, whereas AD and MWAD litchis have a compact structure. The sensory evaluation suggests that peeled litchis dried by the four studied drying methods are of a quality that is accepted by consumers.     

荔枝果皮色差a*值与其他品质指标的关联性

褐变是影响荔枝销售的主要因素之一,为掌握荔枝颜色变化与荔枝品质指标的关联关系,以"桂味"为试验材料,采用带孔PE袋进行包装,分别将其贮藏于气调和冷藏2种贮藏保鲜模式30d,研究了荔枝果皮色差a*值与其他品质指标的变化关系,并拟合成线性关系式。研究结果表明:气调模式比冷藏模式有利于抑制荔枝果皮色差a*值变化,荔枝果皮色差a*值分别从35.0降至28.97和20.96;荔枝果皮色差a*值与果皮失水率、褐变指数、花色素苷含量、果实失重率以及感官评定值成线性关系,平均相关系数为0.8609;荔枝果皮色差a*值与其电导率、pH值线性关系不显著,平均相关系数分别只有0.5392和0.4977;冷藏模式下,除感官评定值外,荔枝果皮色差a*值与其他品质指标的线性相关性要高于气调模式,平均相关系数分别为0.9465和0.7752。研究结果对研究以果皮色差预测荔枝贮藏期及货架期具有一定的参考价值。     

荔枝核淀粉理化特性的研究

利用SEM、X-光射线衍射、Brabender黏度仪、DSC等研究荔枝核淀粉的理化性质。结果表明:荔枝核淀粉颗粒多呈椭圆形或多角形,平均粒径为12.6μm;有明显的黑十字且交叉点在颗粒中心;颗粒晶体结构为C型;起糊温度较高,为85.3℃,热稳定好,有黏度峰值,为177BU;DSC测得T°、Tp、Tc分别为69.04℃、78.79℃、87.08℃,ΔHgel为7.50J/g;支链淀粉、直链淀粉含量分别为88.8%和11.2%。     

荔枝果实中营养元素的测定

采用原子吸收法测定了广东地区20种荔枝中钾、钙、钠、镁、铁、锰、铜和锌8种元素在果肉、果皮和果核中的分布,方法的相对标准偏差介于0.2～1.9％,平均回收率为98.1～104.2％.对不同荔枝品种营养元素含量的变化及其分布的规律性进行了讨论,结果表明元素的分布特征和荔枝品种具有一定相关性,为进一步研究荔枝的药效和保健作用及综合利用提供参考.     

糯米糍荔枝叶片矿质养分含量充足范围的确定

对深圳市4个典型丰产园糯米糍荔枝叶片7种矿质养分(氮、磷、钾、钙、镁、锌和硼)含量的统计分析表明:采样地点和生育时期均对叶片营养元素含量有显著的影响。四个关键生育时期(末次秋梢老熟期、花芽形态分化期、谢花期和果实成熟期)的单株样与混合(多株)样的供试矿质养分含量之间大部分没有显著差异。本研究根据丰产园糯米糍荔枝叶片混合样的分析结果提出了7种矿质养分的充足含量范围。