Changes in anthocyanin concentration in Lychee (Litchi chinensis Sonn.) pericarp during maturation

Lychee has an edible aril surrounded by an anthocyanin-rich pericarp. Chemical and physical changes during lychee ripening were studied focusing on anthocyanins (Acy). Length increased up to the 17th week after anthesis (waa), and width and weight increased continuously. Pericarp % decreased until the 17th waa while aril % increased until the 19th waa. The fruit became darker during ripening and changed from light green to yellow-green (12–15th waa), and from yellow-red to dark red (16–20th waa). pH decreased from 3.18 to 2.68 (12–15th waa), finally increasing to 4.49. Highest titratable acidity occurred in the 14th waa (4.44% malic acid) decreasing to a final 0.16%. Soluble solids were highest at ripeness (18 °Bx). Increases in monomeric (mAcy) and total Acy levels were observed up to the the 17th waa. Green fruits contained only malvinidin-3-acetylglucoside and polymeric pigment while the ripe fruit contained cyanidin-3-rutinoside (>75%), cyanidin-3-glucoside (<17%) and malvinidin-3-acetylglucoside (<9%).     

Anti-Inflammatory Effects of Lychee (Litchi chinensis Sonn.) Seed Peptide Hydrolysate on RAW 264.7 Macrophage Cells

Lychee (Litchi chinensis) seeds, a by-product from the canned lychee processing, were hydrolyzed using various concentrations of proteases (Alcalase, Flavourzyme, and Neutrase). The protein hydrolysate produced with Neutrase at a concentration of 50 mg/mL exhibited the highest free radical scavenging activity. After ultrafiltration, the fraction containing peptides of less than 650 Da was purified by using gel filtration chromatography into G1–G3. The G1 fraction exhibited the highest activity and was further purified by reversed phase high performance liquid chromatography (RP-HPLC). Four fractions (H1–H4) were isolated and exhibited efficient nitric oxide (NO) scavenging activity. The G1 fraction inhibited NO production in lipopolysaccharide (LPS) stimulated RAW 264.7 cells with down-regulation of inducible nitric oxide synthase (iNOS) and interleukin-6 (IL-6). The results showed that lychee seed peptide hydrolysates exhibited potent anti-inflammatory activities, suggesting the peptides may be useful as additives to health products such as functional foods and/or pharmaceuticals.     

不同包装薄膜对荔枝气调贮藏品质的影响研究

为研究不同包装对荔枝果实气调贮藏品质的影响,在果蔬气调保鲜贮运实验平台上,以\     

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。     

Vital Characteristics of Litchi (Litchi chinensis Sonn.) Pericarp that Define Postharvest Concepts for Thai Cultivars

To assess the fruit-specific determinants of pericarp browning, litchi pericarp was characterized in terms of appearance, the polyphenol pattern as specified by HPLC-DAD-MS ⁿ without and after thiolysis, and the activities of polyphenol oxidase (PPO) and peroxidase (POD) by exploring “Kwang Jao,” “O-Hia,” “Kim Cheng,” and “Chacapat” fruit on the respective harvest day, “Hong Huey” fruit also throughout 52 days of cold storage (5 °C, 95% relative humidity). At harvest, PPO activity was maximum for “Kim Cheng” pericarp (126 μkat/hg), whereas POD activity was striking for that of “O-Hia” (512 μkat/hg, including membrane-bound isoforms). Flavan-3-ol and proanthocyanidin patterns were consistent for all cultivars. However, cultivars with sharp-pointed and round–obtuse protuberances differed in pericarp anthocyanin and flavonol glycosylation patterns. The molar ratio of cyanidin 3-O-rutinoside to its glucoside was ≤6:1 for “Hong Huey” and “Kwang Jao,” but ≥43:1 for “Kim Cheng” and “Chacapat” pericarp. Long-term storage gave evidence of two key processes involved in pericarp browning: (1) PPO-mediated oxidation of abundant (?)-epicatechin (1.4–2.0 g/hg), resulting in dark brown pigments, and (2) microcrack-induced formation of light brown surface scurf, supposably with involvement of POD. Accordingly, an improved scheme for litchi pericarp browning was proposed. As regards recommendable postharvest concepts for each cultivar, “Chacapat” suited most for long-distance transports due to its overall low susceptibility to pericarp browning. Properties of “O-Hia” litchi, being prone to surface scurf formation, suggested preferred distribution via domestic markets. High contents of flavonols (e.g., quercetin glycosides, 166 mg/hg) and A-type-linked procyanidins (e.g., procyanidin A2, 1,092 mg/hg) qualified pericarp of “Hong Huey” litchi as raw material for polyphenol extracts exerting antioxidant properties.     

不同品种荔枝果肉细胞抗氧化及抗增殖活性评价

为明确荔枝果肉的生物抗氧化和抗肿瘤保健功能,采用HepG2人肝癌细胞模型对我国南方地区主要种植的10种代表性荔枝品种果肉的细胞抗氧化活性(CAA值)和抗肿瘤细胞增殖活性进行了评价。结果表明,10种荔枝品种中,妃子笑荔枝果肉具有最大的CAA值,淮枝则最小;妃子笑抗HepG2肿瘤细胞增殖活性最强,糯米糍则最弱。荔枝果肉的CAA值与总多酚含量、总黄酮含量、多酚化学抗氧化能力指数(ORAC值)之间都有极显著的正相关性(p0.01),且与黄酮含量之间正相关性最大,说明荔枝果肉中起生物抗氧化作用的主要成分是黄酮类化合物;但荔枝果肉对HepG2肿瘤细胞的抗增殖活性与总多酚含量、总黄酮含量、ORAC和CAA值之间均呈现较弱的负相关性(p0.05),提示某些特殊酚类单体或其协同作用在抗肿瘤细胞增殖过程中发挥主要作用。     

火龙果粉冷冻-真空微波干燥工艺优化及贮藏品质

为优化火龙果粉的冷冻干燥结合真空微波干燥工艺并研究其贮藏品质,以火龙果为原料,以复水比和维生素C 保留率加权转化的综合评分为指标,通过单因素和响应面试验优化火龙果粉的工艺条件并分析其贮藏品质。结果表明,优化后的工艺条件为采用冷冻干燥将火龙果干燥到水分含量35% 后,再采用真空度40 Pa、微波功率1 500 W 的真空微波干燥继续将其干燥至水分含量3.5%。该条件下,产品实际综合评分为85.17,与理论预测值基本吻合。联合干燥技术的产品在25 ℃、相对湿度65% 的条件下贮藏30 d 时,火龙果粉中的VC 保留率为（83.36±0.65）%,感官评分65.6,VC 的保留率和感官评分均较高,具有较好的贮藏品质。     

Inhibitory effects of litchi (Litchi chinensis Sonn.) flower-water extracts on lipase activity and diet-induced obesity

Litchi flower–water extract (LFWE) contains plenty of phenolic acids, flavonoids, condensed tannins, anthocyanins, and proanthocyanidins. In this study, we used eight male rats per group that were assigned randomly to one of the following dietary group: (1) normal-caloric diet and distilled water; (2) hypercaloric diet (HCD) and distilled water; (3) HCD and 2.5% LFWE; (4) HCD and 5% LFWE for 10 weeks. As results, LFWEs demonstrated a suppressive (p < 0.05) effect on in vitro lipase activities; meanwhile, larger sizes of livers, perirenal and epididymal adipose tissues, and cell sizes of epididymal adipose tissues in hypercaloric-diet-fed group were decreased (p < 0.05) by drinking LFWEs, especially in 5% LFWE-treated groups. Increased (p < 0.05) serum cholesterol and liver lipid levels were measured in hypercaloric-diet-fed rats. However, drinking LFWEs also decreased (p < 0.05) those levels to that similar to the NCD group, whereas drinking LFWEs resulted in higher (p < 0.05) faecal lipid concentrations. It also corresponded to the liver TNF-α and IL-1β values which were ameliorated (p < 0.05) in hypercaloric-diet-fed rats with LFWEs. Therefore, the result of this investigation match the anticipation, which LFWE indeed possesses a potential nutraceuticals for anti-obesity effects.     

微波真空与真空冷冻组合干燥对芦笋营养与品质的影响

为获得优良的芦笋干燥制品,采用微波真空干燥和真空冷冻干燥技术对芦笋进行不同的组合干燥处理,并对干燥芦笋的营养成分和品质进行评价。以芦笋为原材料,通过不同的微波真空和真空冷冻干燥组合对芦笋进行干燥处理,以芦笋的冻干时间、含水量、复水性、成分、色泽等指标,确定芦笋干燥的工艺技术参数。结果显示:微波干燥2 min后再进行冷冻干燥12 h芦笋脱水率可达95.4%;以微波干燥2 min后再冻干20 h的芦笋色泽最优;纯冷冻干燥的芦笋复水比较好,8 min可达10.38;冷冻干燥对芦笋VC含量影响较小,微波处理对芦笋VC含量有一定损失;真空冷冻干燥芦笋保留蛋白质和总糖含量高于微波处理后再冷冻干燥的芦笋;微波处理的芦笋对细菌和真菌都有显著的杀菌作用,但对细菌的杀菌效果好于真菌。对减少芦笋加工过程中营养成分的损失,提高干燥产品品质和芦笋工业化深加工提供了理论依据。     

深圳“南山荔枝”的品质分析与喜好度研究

妃子笑、糯米糍和桂味是深圳市最受欢迎的荔枝品种。通过理化检测分析三种荔枝中与口感相关的品质指标,妃子笑的含糖量及总甜度高于桂味和糯米糍,三种荔枝中均含有8种有机酸,其中酒石酸、苹果酸和柠檬酸含量较高,妃子笑的总有机酸含量高于桂味和糯米糍。通过9标度喜好度检验实验研究三种荔枝的喜好度,按喜好度从高到低为:桂味>糯米糍>妃子笑。喜好度顺序与总糖/可滴定酸度比值无显著相关性(p>0.05),与总糖/总有机酸比值高度相关(p<0.01),与果肉的质构也存在高度相关性(p<0.01)。      

Effects of high-pressure treatment on the extraction yield, phenolic content and antioxidant activity of litchi (Litchi chinensis Sonn.) fruit pericarp

As a promising technique, high-pressure extraction (HPE) method was used to extract bioactive compounds from litchi fruit pricarp. The study involved in different experimental factors such as solvent, ethanol concentration (35-95, v/v), material to solvent ratio (1:25-1:100, w/v), acidic medium, extraction pressure (200-500 MPa), time (2.5-30 min) and temperature (30-90 °C). The extraction yield, total phenolic contents, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide anion scavenging capability of the HPE sample were examined and then compared with those of ultrasonic extraction and conventional extraction samples. The application of HPE obtained higher extraction yield compared to other extraction methods. However, there were no significant differences ( P  >   0.05) in the total phenolic content and the antioxidant activities among these various extractions. Compared with some conventional extraction method, the HPE exhibited higher extraction efficiency in terms of higher extraction yield and extraction time.     

真空微波干燥中微波强度对胡萝卜和南瓜中类胡萝卜素生物利用率的影响

为明确真空微波干燥过程中,微波强度对胡萝卜和南瓜中类胡萝卜素生物利用率的影响,本文采用静态体外模拟消化模型评价类胡萝卜素生物利用率的变化,采用透射电镜（TEM）和光学显微镜观察细胞壁微观结构的变化。结果表明,真空微波干燥后的胡萝卜和南瓜的细胞壁断裂,有色体结构破坏严重。经体外模拟消化,胡萝卜和南瓜消化液细胞结构破坏明显,细胞壁破裂严重,类胡萝卜素从细胞内部释放到消化液中的含量明显高于鲜样,且类胡萝卜素生物利用率随微波强度的增加呈现先升高后降低的趋势。当微波强度为9 W/g时,胡萝卜和南瓜中类胡萝卜素的生物利用率较高,其β-胡萝卜素生物利用率相比于鲜样分别显著提高了12.02、24.2倍（P<0.05）。由此可知,选择合适的微波强度有助于提高蔬菜中类胡萝卜素生物利用率。     

基于控温的莲子微波干燥特性及干燥品质研究

为了探索基于控温下的莲子微波干燥特性及干燥品质,研究不同微波功率、物料表面温度区间对莲子微波干燥特性的影响,对莲子进行了微波控温干燥试验,并将基于控温下的微波干燥莲子与热风干燥莲子在品质上进行了分析。研究结果表明:物料表面温度对莲子干燥影响较大,物料表面温度区间越大,莲子干燥速率越快,干燥时间越短;微波干燥功率对莲子干燥影响较小。采用7种常见的薄层干燥模型对控温微波干燥过程进行拟合,结果表明Midilli模型是最适合描述在莲子微波控温干燥过程中水分变化规律的薄层干燥模型。根据Fick第二定律得出莲子控温微波干燥的有效扩散系数为8.9891×10^-10~2.22431×10^-9 m²/s;由Arrhenius方程得出莲子微波控温干燥的活化能为79.85 kJ/mol。两种干燥方式干燥的莲子复水率差异不显著(p>0.05);莲子控温微波最短干燥时间低于热风干燥。研究结果可为莲子控温微波联合干燥工艺提供参考。     

Antioxidative and anti-inflammatory effects of polyphenol-rich litchi (Litchi chinensis Sonn.)-flower-water-extract on livers of high-fat-diet fed hamsters

Gentisic acid and epicatechin are two major compounds in phenolic acids and flavonoids of litchi-flower-water extracts (LFWEs), respectively. Increased (p < 0.05) serum lipids and liver size/lipid, damage/inflammatory indices, TBARS value, CRP level, MMP-9 activity, and decreased (p < 0.05) liver GSH and TEAC levels, and SOD, CAT and GSH-Px activities were observed in high-fat-diet fed hamsters compared to normal-fat-dietary hamsters. Those biochemical values of high-fat-diet fed hamsters were significant improved (p < 0.05) by drinking LFWEs. In addition, these improvements on liver damage induced by a high-fat diet were also evidenced in the histopathological examination of livers where less microvesicular steatosis and no necrotic/inflammatory cells were observed in high-fat-diet fed hamster drinking LFWEs. Therefore, protective effects of LFWEs on liver damage of high-fat-diet fed hamsters can be accounted for antioxidative properties and anti-inflammatory effects of LFWEs.     

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.     

Measurement and Modeling of Moisture Sorption Isotherm of Litchi (Litchi Chinensis Sonn.)

The equilibrium moisture contents of litchi (Litchi Chinensis Sonn.) were experimentally determined using the dynamic method at temperatures of 30, 40, and 50°C over a range of relative humidity values of 12 to 95%. Five models were tested to fit the experimental isotherm data of litchi. The GAB model fitted the best to experimental isotherm data. The agreement between experimental and predicted values of this model is excellent (RMSE 1.8 to 3.4%). The isosteric heats of sorption water were also determined from the equilibrium data using the Clausius-Clapeyron equation and it was found to be a function of equilibrium moisture content.     

几种不同干燥方法对荔枝肉干燥品质的影响

作者对剥壳荔枝用热风干燥法、热风微波耦合干燥法、微波真空干燥法及真空冷冻干燥法进行干燥,分别取其最优的干燥工艺并进行对比,通过测定不同干燥方法的蛋白质、还原糖的成分和色泽,分析干燥产品的质量,据此可根据不同的需求选择不同的干燥方法.     

冷冻预处理及负压微波喷动干燥对脱水牛蒡品质的影响

以牛蒡为主要原料,在干燥腔内真空压力波动范围为12~21 kPa的条件下,研究喷动频率、微波功率,以及预处理方式,对负压微波喷动干燥(PSMVD)牛蒡片的干燥特性及质构、收缩率、复水比、感官评分、色泽等品质的影响。结果表明:喷动频率、微波功率,以及预处理方式对其影响较大,当喷动频率为3.3 r/min,微波功率为19.8 W/g,采用冷冻预处理(-18℃,12 h)的方式,所得到的牛蒡产品色泽佳、质地松脆、风味浓郁、保质期长。