荔枝皮综合利用的研究进展

荔枝是一种营养价值较高的水果，荔枝果皮中的营养成分具有较强的生理活性。然而，大量荔枝果皮作为副产物并没有得到有效地开发和利用，并且关于其营养成分的研究鲜见。该文对荔枝果皮的主要化学成分进行综述，解析荔枝果皮主要化学成分的生物活性，比较对主要化学成分的不同提取方法，并探索其在食品保鲜、水处理、生物医药、化妆品与新能源材料方面的综合利用现状，同时对荔枝果皮的开发前景进行展望，对荔枝果皮进一步开发、探索具有重要意义。     

荔枝果皮褐变机理和防褐研究的发展方向

荔枝原产于我国南部，具有良好的经济价值，但同时也不易储藏保鲜，容易褐变。本文综述了国内外有关荔枝果皮褐变机理的研究进展，并对今后荔枝防褐技术研究的发展方向提出建议。     

气调贮运摆放位置对荔枝保鲜品质的影响

为研究保鲜气调运输厢体内荔枝不同摆放位置对保鲜品质的影响,采用果蔬气调保鲜运输试验平台对"淮枝"荔枝进行气调贮藏。隔7 d对不同摆放位置的荔枝样品进行测试,测试指标为果皮褐变指数、质量损失率、果皮色差值、可滴定酸以及可溶性固形物含量,并结合厢体内的温度场、湿度场进行分析。试验结果表明:在贮藏期内,厢体内温度呈前低后高、上低下高分布;而相对湿度呈前高后低、上低下高分布。不同纵向摆放位置对无包装荔枝的果皮褐变指数、质量损失率影响较大,质量损失率自上而下逐步减小;处于厢体后部的荔枝的可滴定酸含量较前部和中部的荔枝要高;处于厢体中部的荔枝的可溶性固形物含量要比前、后部的荔枝低。本研究结果为果蔬贮运保鲜提供一定的参考。     

荔枝果柄处理对其常温贮藏特性的影响

为掌握荔枝果柄不同处理方式对其常温贮藏特性的影响,以"淮枝"荔枝为试验对象,分别在去柄、带柄和鲜插3种处理方式下,测定其褐变指数、色泽(L*,a*,b*值)、果皮含水率、果皮厚度、果肉可溶性固形物和可滴定酸含量等指标的变化。分析果柄处理对其耐贮性能的影响,结果表明:鲜插处理的保鲜效果依次优于带柄和去柄。鲜插处理可以抑制果皮a*值下降,延缓果皮褐变以及厚度降低,并且较好地维持了果皮含水率。对于3 d以内的短期贮藏,果柄对荔枝保鲜品质影响不大。超过4 d以后,果柄对荔枝果实外观色泽和风味的保持起到一定作用。该文可为荔枝贮藏保鲜技术与装备开发提供一定参考。     

荔枝无公害热处理保鲜技术

采用无公害热处理技术,研究了荔枝经热水处理后果皮的褐变指数;在整个过程中不使用有毒有害化学物质;经保鲜处理后,荔枝在(2±1)℃下贮藏32d果皮颜色、果肉及味道无明显变化,40d后果皮才逐渐开始褐变。     

几种保鲜模式对荔枝贮藏效果对比

为研究保鲜模式对荔枝果实贮藏品质变化的影响,在模式可控的保鲜厢体上,以"桂味"荔枝果实作为试验材料,分别在气调、控温控湿和仅控温3种保鲜模式下,开展荔枝果实贮藏试验,比较不同保鲜模式对荔枝果实贮藏效果的影响。试验结果表明,贮藏20 d后,气调模式荔枝的好果率接近1.00,控温控湿模式好果率为0.81,仅控温模式荔枝好果率为0.59;在贮藏期前5 d,不同保鲜模式下的荔枝果实品质差异不显著;仅控温模式荔枝在贮藏过程中果皮水分百分含量迅速下降至0.57、果实失重率迅速增长至11.52%;气调和控温控湿模式下,荔枝果实失重率分别上升至2.91%和2.05%,果皮水分百分含量分别从0.73降至0.69和0.71;不同保鲜模式对荔枝果肉TSS和TA含量变化影响不显著;第20 d货架期试验表明,气调模式能够延缓荔枝果实货架期失重率的变化。研究结果为荔枝果实贮运方式选择提供一定的参考。     

茶树油、丁香酚、柠檬醛在荔枝保鲜中的应用

本文研究了茶树油、丁香酚和柠檬醛的挥发性香氛对荔枝的保鲜作用,采用复配方法探究三种香料对荔枝的协同保鲜效果。结果表明:在冷藏(4±1℃)过程中,茶树油和丁香酚、柠檬醛的挥发性香氛可抑制荔枝果实腐败,延缓果皮衰老和果肉维生素C含量的降低,对保持荔枝果实的感官品质也具有积极作用;且三者复配后效果更佳,贮藏至18天,复配组荔枝的腐败率、果皮相对渗透率、维生素含量分别为对照组的56.0%、72.8%、124.8%,果皮颜色、果实滋味、果实气味和整体评价分别比对照组高2.4、3.3、2.6和3.4分。     

复配植酸保鲜剂对荔枝果实的保鲜效果

报道了植酸复配苯甲酸和柠檬酸对荔枝果实的保鲜效果。新鲜荔枝经复配植酸保鲜剂处理5～10min,3±1℃贮藏40d,根据果皮褐变、感官指标、腐烂程度和营养成分的变化评定保鲜效果。结果表明,复配植酸保鲜剂可使荔枝果实保鲜期达到40d左右,果肉品质、风味、果皮色泽保持良好。     

葡甘露聚糖改性复合膜在荔枝常温涂膜保鲜应用

荔枝在采摘之后,很容易会散失水分,表皮磨损,滋生微生物等不利于其储藏保鲜。利用葡甘露聚糖改性复合膜,在荔枝果皮上涂膜,与周围环境之间建立一道屏障,保护荔枝果实。     

复配植酸保鲜剂对荔枝果实的保鲜效果

本文报道植酸复配苯甲酸和柠檬酸对荔枝果实的保鲜效果。新鲜荔枝经复配植酸保鲜剂处理5～10min,3±1℃贮藏40d,根据果皮褐变,感官指标,腐烂程度和营养成分的变化评定保鲜效果。结果表明:复配植酸保鲜剂可使荔枝果实保鲜期达到40d左右,果肉品质、风味、果皮色泽保持良好。     

不同温度和包装方式对荔枝保鲜品质的影响

为掌握温度和包装对荔枝货架期的影响,本试验以“淮枝”荔枝为试验材料,以裸露的荔枝和由开孔袋包装的荔枝,分别处于常温货架和低温货架,研究不同因素对荔枝质量损失率、褐变指数、好果率、色差、可溶性固形物含量和可滴定酸含量的影响。试验表明：低温货架和包装都能延长荔枝货架期,各品质指标整体衰变速度从快到慢依次为：常温裸露、常温包装、低温裸露、低温包装。对荔枝货架期影响因素中,温度占主要影响作用,低温货架有效的降低了荔枝各指标的变质速度;开孔聚乙烯薄膜包装也能降低荔枝品质的衰变,该影响小于货架温度的影响。常温货架无包装的荔枝好果率在30 h变为0,低温包装荔枝的好果率在60 h仍保有9.20%。与常温货架荔枝裸露的销售方式对比,采用低温货架并由开孔聚乙烯薄膜包装可以使荔枝货架期延长一倍以上。该文为荔枝货架期保鲜研究提供了参考。     

荔枝果汁产品开发与市场策略分析

荔枝是我国岭南特色水果之一,其采收季节短,贮藏保鲜难度大,鲜果供应期集中,限制了荔枝产业的健康发展。荔枝加工产品主要包括荔枝干、荔枝罐头等。果汁加工具有原料消耗量大,市场需求高,对水果原有营养成分保存较多的特点,因此一直是水果加工的最主要形式,但目前荔枝果汁产品还鲜见于市场。本文探讨了以荔枝为原料,加工成为果汁系列产品的可行性和市场策略,以期为荔枝产业的持续发展提供有益的思路。     

Oxidation of (−)-epicatechin is a precursor of litchi pericarp enzymatic browning

The degradation of flavanols had been studied both in the litchi pericarp during the storage and in the model system containing PPO and flavanols of litchi pericarp. The results showed that (−)-epicatechin was the optimal endogenous substrate of litchi pericarp PPO, and the procyanidins of litchi pericarp were oxidised very slowly when incubated alone with PPO. However, (−)-epicatechin could accelerate the oxidation of the other flavanols in litchi pericarp through a coupled oxidation pathway. The results obtained allowed us to draw a conclusion that the oxidation of (−)-epicatechin was a precursor of litchi pericarp browning. A pathway of enzymatic browning of litchi pericarp was proposed as follows: with the loss of cellular compartmentation, the litchi pericarp PPO and flavanols mixed and, then, (−)-epicatechin was oxidised by the PPO and o-quinones formed. The o-quinones reacted with other flavanols and anthocyanins, accelerating the oxidation of other polyphenols. Finally, the oxidation of (−)-epicatechin and other polyphenols led to the formation of the brown-coloured compounds, resulting in the enzymatic browning of litchi pericarp.     

基于GC-IMS和GC-MS分析不同杀菌处理荔枝果汁及其发酵汁挥发性物质的特征

采用气相色谱-离子迁移谱（Gas Chromatography-Ion Mobility Spectrometry,GC-IMS）和气相色谱-质谱联用（Gas Chromatography-Mass Spectrometry,GC-MS）分析了热杀菌和超高压前处理对荔枝汁及其乳酸菌发酵汁挥发性物质的影响。结果表明,GC-IMS共检出70种挥发性化合物,以酮类、醇类、酯类、醛类和萜类为主,热杀菌导致新鲜荔枝汁中的丙酸乙酯、2-甲基丙酸甲酯、苯甲醇和1-辛烯-3-醇等成分损失严重,经发酵后其中的丙酸丁酯、三甲基吡嗪、5-壬酮和2,5-二甲基噻吩等成分含量更丰富。而超高压前处理荔枝汁与新鲜荔枝汁组分相似,经发酵后其中的芳樟醇、2,6-二甲基吡嗪、顺式玫瑰醚、苯甲醛等成分含量更丰富;GC-MS共鉴定出51种挥发性化合物,以萜类、醇类为主,热杀菌导致荔枝汁中萜类和醇类含量分别降低了37.05%和31.61%,超高压前处理荔枝汁中萜类和醇类含量则较鲜汁分别增加了33.57%和80.07%,而热杀菌和超高压前处理发酵荔枝汁挥发性化合物总量较发酵前分别增加了46.93%和46.19%,且超高压前处理发酵荔枝汁是热杀菌发酵荔枝汁的2.11倍,更富有愉悦性香气。两种技术相结合,表明了超高压前处理能有效改善荔枝汁及其发酵汁的香气品质,为提升荔枝发酵汁的品质提供了参考价值。     

荔枝核淀粉提取工艺研究

采用超声波浸提与酶处理的方法提取荔枝核淀粉,通过正交设计确定荔枝核淀粉提取的工艺参数,并对荔枝核淀粉成分及理化性质进行研究.结果表明:荔枝核淀粉提取最佳工艺为:酶用量1%,酶解时间4h,酶解前先超声波振提40min,浸泡时间为4h.采用该工艺提取荔枝核中的淀粉,粗淀粉提取率为52.90%,粗淀粉中淀粉质量含量为73.95%,直链淀粉11.11%,蛋白质含量7.38%,脂肪含量1.38%,灰分0.51%.     

Diffusivity,shrinkage and simulated drying of litchi fruit (Litchi Chinensis Sonn.)

Litchi (Litchi Chinensis Sonn.) is an important commercial fruit in Thailand and Vietnam. Litchi fruit is consumed both as fresh and dried products. Also most of the export of litchi is in the form of dried whole litchi fruit. Thermo-physical properties and drying model of litchi fruit is important for optimum design of litchi dryer. This paper presents moisture diffusivity, shrinkage and finite element simulated drying of litchi fruit. The moisture diffusivities of litchi were determined by minimizing the sum of square of deviations between the predicted and experimental values of moisture content of thin layer drying under controlled conditions of air temperature and relative humidity. The components in the form of cylinder for seed and seed stalk and slab for seed coat, shell and flesh were dried in thin layers at the air temperatures of 50, 60, 70 and 80 °C and relative humidity in the range of 10–25%. The mean diffusivity of flesh, seed and shell of litchi fruit increased with temperature and was expressed by the Arrhenius-type equation, but the diffusivities of seed coat and seed stalk were independent of temperature. The moisture diffusivities of seed coat and seed stalk were much lower than those of the other parts of the litchi. The shrinkage of litchi fruit has also been determined experimentally and it was expressed as a function of moisture reduction. A two-dimensional finite element model has been developed to simulate moisture diffusion in litchi fruit during drying. Shrinkage of the flesh and different component diffusivities of litchi during drying were also taken into account. The finite element model was programmed in Compaq Visual FORTRAN version 6.5. This finite element model satisfactorily predicts the moisture diffusion during drying. Moisture contents in the different components in the litchi fruit during drying were also simulated. This study provides an understanding of the transport processes in the different components of the litchi fruit.     

Nutrient components,health benefits,and safety of litchi (Litchi chinensis Sonn.): A review

Litchi (Litchi chinensis Sonn.) is a tropical to subtropical fruit that is widely cultivated in more than 20 countries worldwide. It is normally consumed as fresh or processed and has become one of the most popular fruits because it has a delicious flavor, attractive color, and high nutritive value. Whole litchi fruits have been used not only as a food source but also for medicinal purposes. As a traditional Chinese medicine, litchi has been used for centuries to treat stomach ulcers, diabetes, cough, diarrhea, and dyspepsia, as well as to kill intestinal worms. Both in vitro and in vivo studies have indicated that whole litchi fruits exhibit antioxidant, hypoglycemic, hepatoprotective, hypolipidemic, and antiobesity activities and show anticancer, antiatherosclerotic, hypotensive, neuroprotective, and immunomodulatory activities. The health benefits of litchi have been attributed to its wide range of nutritional components, among which polysaccharides and polyphenols have been proven to possess various beneficial properties. The diversity and composition of litchi polysaccharides and polyphenols have vital influences on their biological activities. In addition, consuming fresh litchi and its products could lead to some adverse reactions for some people such as pruritus, urticaria, swelling of the lips, swelling of the throat, dyspnea, or diarrhea. These safety problems are probably caused by the soluble protein in litchi that could cause anaphylactic and inflammatory reactions. To achieve reasonable applications of litchi in the food, medical and cosmetics industries, this review focuses on recent findings related to the nutrient components, health benefits, and safety of litchi.     

副干酪乳杆菌FX-6产抗菌肽粗提物对荔枝贮藏品质的影响

通过离体实验研究了副干酪乳杆菌FX-6产抗菌肽粗提物对荔枝霜疫霉菌生长的抑制作用,并且以施保克咪鲜胺处理作为对照,研究了两种质量浓度的抗菌肽粗提物在25℃条件下对荔枝贮藏品质的影响。结果表明,抗菌肽粗提物能显著抑制荔枝霜疫霉菌的生长,改善荔枝的贮藏品质,抑制霉变及褐变,维持果肉的营养成分含量;0.5 mg/m L的抗菌肽粗提物效果优于相同质量浓度的施保克咪鲜胺,且1.0 mg/m L抗菌肽粗提物的效果更佳。可见,副干酪乳杆菌FX-6产抗菌肽粗提物能有效延长荔枝的常温贮藏期,具有潜在的应用价值。     

A Comparison of mango kernel starch with a novel starch from litchi (Litchi chinensis) kernel: Physicochemical,morphological, pasting,and rheological properties

A novel starch was isolated from litchi kernel and compared with mango kernel starch. The properties studies were physicochemical, morphological, pasting, rheological, X-ray diffraction, and morphological. Litchi kernel starch had significantly (p < 0.05) higher amylose content and solubility, whereas its swelling power and paste clarity were lower than mango kernel starch. Peak viscosity and breakdown viscosity of litchi kernel starch were lower than mango kernel starch; however, it showed higher setback viscosity. The scanning electron microscopy revealed the presence of starch granules varying in size and shape from small to large and oval to elliptical, respectively, in litchi kernel starch. The mean length of small and large litchi starch granules was 9.52 and 50 µm, respectively, while the mean breadth of small and large litchi starch granules was 7.14 and 35.7 µm, respectively. X-ray diffractions of both litchi and mango kernel starches showed typical A-type patterns. During heating, litchi kernel starch showed higher peak G’ (storage modulus), G’’ (loss modulus), and breakdown in G’ in comparison to mango kernel starch. The peak tan δ of litchi and mango kernel starch was <1, which indicated that both litchi and mango kernel starches were more elastic than viscous.     

肉桂醛抗菌复合保鲜剂涂膜对采后荔枝的保鲜效果

对贮藏期荔枝的主要致腐菌进行科赫氏验证、形态学分析和ITS序列鉴定,优化肉桂醛抗菌复合保鲜剂的配方,探究其在荔枝保鲜中的应用效果。结果显示:引起荔枝腐烂的主要致腐菌为黑根霉(Rhizopus nigricans),肉桂醛复合保鲜剂可明显抑制荔枝的霉变。复合保鲜剂的组分(壳聚糖、玉米醇溶蛋白、甘油)均可显著减缓荔枝果实的可溶性固形物质量分数的下降和质量损失率的上升,延长荔枝的贮藏期;根据综合平衡法从正交试验组合中优选出复合保鲜剂最佳配方,即壳聚糖质量浓度1.2 g/100 mL、玉米醇溶蛋白质量浓度1.6 g/100 mL、甘油质量浓度0.7 g/100 mL、肉桂醛质量浓度750 mg/L。优选配方处理荔枝常温贮藏8 d时,果皮腐烂指数0.16,商品果率92.3%,贮后果皮色泽鲜亮,感官品质好,保鲜效果佳。