芦荟汁保鲜番茄的研究

用芦荟汁为主要成分制成涂被液对番茄进行涂膜保鲜研究。结果表明:芦荟汁涂被液对番茄具有明显的保鲜作用。以库拉索芦荟为主要成分制成的涂被液保鲜效果最好,1%库拉索芦荟汁、0.5%淀粉、0.2%甘油等体积混合,是最佳涂被液。经此涂被液保鲜处理的番茄其失重率、烂果率和褐变指数最低,总糖、总酸、VC和氨基酸含量变化幅度最小。此配方为最优配方。     

壳聚糖在蒜米涂膜保鲜中的应用研究

以壳聚糖为主剂,加入不同助剂配制成涂膜液,于常温下对蒜米进行涂膜保鲜试验,研究壳聚糖涂膜对蒜米贮藏效果的影响。试验结果表明:配制壳聚糖涂膜液的最适助剂为乙酸1.0%、甘油0.5%、吐温200.2%。壳聚糖涂膜处理可降低蒜米贮藏期间的失重率,抑制呼吸、发芽、MDA的生成,降低总糖的消耗,延长蒜米的贮藏期,保鲜效果以1.5%的壳聚糖为最好。     

壳聚糖保鲜剂涂膜对保鲜葡萄的效果研究

研究了壳聚糖保鲜剂涂膜保鲜葡萄。采用壳聚糖为成膜主剂,表面活性剂为助剂,测定了添加不同表面活性剂的壳聚糖溶液的吸光度和涂布效果。在此基础上,添加不同金属离子的壳聚糖复合保鲜液对葡萄进行了涂膜保鲜处理,并测定了葡萄在贮藏过程中失重率、褐变指数、VC含量和总酸度等生理指标的变化。结果表明：在1%的壳聚糖溶液中添加2%吐温-20、Ca2＋或Cu2＋对葡萄的保鲜效果较好,能有效降低葡萄的失重率,延缓葡萄中总酸度的变化。添加了Ca2＋和Cu2＋的壳聚糖保鲜液对葡萄有较明显的保鲜效果。     

壳聚糖常温保鲜番茄的研究

用壳聚糖作为番茄保鲜剂进行试验。研究结果表明，２％壳聚糖涂膜番茄的总酸度，总糖，维生素Ｃ与新鲜番茄最接近，果实较硬，失水较小，具有较好的保鲜效果。     

壳聚糖处理番茄的保鲜效果研究

将变色期番茄果实浸入浓度为1．5％、2．0％、2．5％的壳聚糖溶液中30s,在常温下贮藏;35d,研究壳聚糖对番茄果实的保鲜效果。结果表明,壳聚糖溶液涂膜处理番茄果实,可延迟果实呼吸跃变,降低呼吸强度;缩小可溶性固形物含量变化幅度;延缓果实硬度、VC、总酸度下降速度;减小失重率,推迟果实腐烂时间,降低腐烂率,从而较好地保持番茄果实的贮藏品质。其中以浓度为2．0％的壳聚糖溶液涂膜保鲜效果最好。     

丝素蛋白改性涂膜处理对番茄保鲜效果研究

目的:为了研究不同浓度丝素蛋白改性壳聚糖铈涂膜处理对番茄采后的保鲜效果。方法:分别用蒸馏水、1%壳聚糖铈配合物、2%、4%、6%丝素蛋白改性壳聚糖铈配合物对番茄进行涂膜处理,并定期对各项理化指标进行测定。结果:表明丝素蛋白改性壳聚糖铈配合物能有效地降低番茄的失重率、呼吸速率,处理组均能抑制多酚氧化酶(PPO)活性上升,同时提高超氧化物歧化酶(SOD)、过氧化物酶(POD)的活性,与对照组相比有显著差异(p0.05)。结论:壳聚糖铈配合物(处理1)相比,丝素蛋白的加入提高了番茄的保鲜效果,其中4%丝素蛋白-壳聚糖铈配合物涂膜处理对室温储藏番茄的保鲜效果最佳,在25℃的条件下,储藏时间比对照组提高23.65%,延长了果实的储藏时间,为番茄的室温短期贮藏提供一种新的方法。     

“枸杞”鸡蛋涂膜保鲜技术的研究

为了研究土鸡饲喂枸杞皮渣所产的鸡蛋的保鲜方法,运用涂膜保鲜技术对鸡蛋进行涂膜处理,以失重率、蛋黄系数、哈夫单位、蛋白pH、浓稀蛋白比为指标,研究壳聚糖-冰醋酸复合涂膜液、壳聚糖-山梨酸钾复合涂膜液、壳聚糖-饱和氢氧化钙复合涂膜液、壳聚糖-面筋蛋白-玉米醇溶蛋白复合涂膜液和普鲁兰糖-甘油-油酸-吐温80涂膜液对鸡蛋的保鲜效果,发现普鲁兰糖-甘油-油酸-吐温80复合涂膜液保鲜效果最好,贮藏25 d后,其失重率为5.1%,蛋黄系数为0.31,哈夫单位为40,蛋白pH为8.93,浓稀蛋白比为0.53。在此基础上,采用响应面法优化浸涂时间和涂膜次数对失重率的影响,得到最佳参数值为:浸涂时间20 s,涂膜次数3 次,在此条件下进行验证试验,验证结果中失重率为2.78%±0.06%,与预测值之间的相对误差为0.007%,表明应用响应面法优化涂膜保鲜工艺是可行的,结果发现\     

羧甲基壳聚糖/海藻酸钠/纳米二氧化硅涂膜保鲜草莓

采用质量分数为1%羧甲基壳聚糖、0.8%海藻酸钠和0.8%纳米二氧化硅为原料配置成复合保鲜液,对新鲜草莓进行涂膜处理。以草莓的腐烂率、失重率、硬度、可溶性固体含量、抗坏血酸含量、可滴定酸含量为指标进行保鲜效果分析。结果表明,复合保鲜液涂膜处理组的草莓保鲜效果最好,且随着羧甲基壳聚糖取代度的增大,复合涂膜的保鲜效果有一定的提升。该复合涂膜能够有效阻止草莓水分的散失和抑制代谢,可应用于草莓的保鲜。     

含茶多酚的壳聚糖涂膜对鸡蛋保鲜效果的影响

用茶多酚和壳聚糖制成的复合涂膜液对鸡蛋进行涂膜处理,以感官指标、失重率、蛋黄指数、蛋清pH值、哈夫单位为质量指标定期取样分析测定,研究所制成的涂膜液在室温条件下对鸡蛋的保鲜效果。结果表明,和对照相比,含茶多酚的壳聚糖涂膜液能较好地保持鸡蛋的新鲜度和品质,尤其以1.5%的壳聚糖溶液联合200mg/kg茶多酚制得的涂膜液保鲜效果最好,经此涂膜液处理后的鸡蛋室温下贮存35d,失重率为1.89%,蛋黄指数为0.26,哈夫单位为60.109,蛋清pH值为8.20。     

天然保鲜剂对朋娜脐橙果实贮藏保鲜效果的研究

利用天然保鲜剂(壳聚糖和1.2%森柏)涂膜液对朋娜脐橙进行保鲜,并测定了不同浓度涂膜液对朋娜脐橙的呼吸强度、失重率、主要有机物含量、腐烂率生理生化指标的影响。结果表明:壳聚糖保鲜效果优于1.2%森柏;2%壳聚糖用于朋娜脐橙保鲜效果最好。      

水溶性壳聚糖稀土配合物对西红柿保鲜及农药残留降解的研究

目的:探索研究水溶性壳聚糖及其稀土配合物对樱桃西红柿的保鲜和农药残留的降解作用。方法:用浓度为1%的水溶性壳聚糖、水溶性壳聚糖铈配合物和水溶性壳聚糖镧配合物水溶液为膜材料,涂膜处理樱桃西红柿,通过好果率、pH变化、失重率和对农药(氧乐果)残留降解的效果考察水溶性壳聚糖及其稀土配合物对樱桃西红柿的保鲜和农药残留的降解作用。结果:处理组各项指标均优于对照组。其中铈配合物最好,镧配合物次之,水溶性壳聚糖最低。结论:水溶性壳聚糖及其稀土配合物对樱桃西红柿有保鲜作用,壳聚糖稀土配合物可模拟降解酶,对有机磷类农药残留有一定的降解效果,其中水溶性壳聚糖铈配合物的降解效果最好,降解度可达到74.09%。      

Fresh tomato specific fluctuations in the composition of lipoxygenase-generated C6 aldehydes

Linoleoyl and α-linolenoyl fatty acyl groups are converted to hexanal and hexenal ((Z)-3-hexenal and (E)-2-hexenal), respectively, on the maceration of tomato fruits. These C6 aldehydes greatly contribute to the mix of volatile compounds which determines the flavour of the tomato. Cherry and standard fresh tomatoes were used to study the relationship between fatty acid composition of the intact fruit and the C6 aldehydes produced on maceration. The cherry tomato (var. Cherry Belle) had approximately twice as much α-linolenic acid as the standard tomato (var. Solairo). The enrichment of α-linolenic acid in the cherry tomato compared to the standard tomato was not evenly distributed between the major lipid classes (neutral lipids, glycolipids and phospholipids) but was prominent in the neutral fraction. The linoleic/α-linolenic acid ratio in the cherry and standard tomatoes was 1.75 and 4.1, respectively; this was reflected but not matched by the hexanal/hexenal ratio on macerating these tomatoes (0.1 and 0.27, respectively). Analysis of volatile compounds on macerating tomato fruits was extended to 14 other commercially available varieties which were nominally split into ‘cherry’ (50 g average fruit weight and below) and ‘standard’ (average fruit weight above 50 g) tomatoes. Hexanal/hexenal ratios were remarkably different between ‘cherry’ (0.05–0.1) and ‘standard’ (0.14–0.27) tomatoes. The concept of increasing α-linolenic acid levels in tomatoes to increase desirable flavour is discussed.     

Study of the volatile composition of tomato during storage by a combination sampling method coupled with gas chromatography/mass spectrometry

BACKGROUND: The volatile compositions of common tomato (Lycopersicon esculentum var. commune) and cherry tomato (Lycopersicon esculentum var. cerasiforme) during storage were studied by a combination sampling method, including headspace solid phase microextraction (HSSPME), simultaneous distillation extraction (SDE) and steam distillation (SD), coupled with gas chromatography/mass spectrometry (GC/MS) detection. RESULTS: Twenty‐one and 14 volatile compounds of fresh and stale common tomatoes and 27 and 17 volatile compounds of fresh and stale cherry tomatoes were identified with various degrees of certainty. The main identified volatile compounds of common and cherry tomatoes were C6 alcohols and aldehydes. During storage, saturated hexanal increased gradually whereas unsaturated (E)‐2‐hexenal decreased. Different volatile compositional characteristics at the fresh and stale storage phases obtained by HSSPME were specified by principal component analysis (PCA). Different metabolic pathways and enzyme catalyses resulted in the various volatile compositional characteristics during tomato storage. Five typical volatile compounds contributing greatly to the difference in volatile compositional characteristics of common and cherry tomatoes at the fresh and stale storage phases were distilled by a common model strategy. These compounds are potential biomarkers for tomato degradation, but further study is needed. CONCLUSION: The preliminary results suggest that the combination of HSSPME and conventional sampling methods would yield more representative information on changes in tomato volatile composition during storage. Copyright © 2007 Society of Chemical Industry     

Variability in the content of soluble sugars and cell wall polysaccharides in red‐ripe cherry and high‐pigment tomato cultivars

BACKGROUND: Soluble sugars and cell wall polysaccharides are well known for contributing to a range of ‘quality’ characteristics of fresh vegetables such as flavour, texture and healthy properties. Red‐ripe berries of 14 cultivars of cherry tomatoes and four cultivars of high‐pigment tomato hybrids, cultivated in the south of Italy, were analysed for their content of these important qualitative parameters. RESULTS: Sakura appeared to be the cultivar with the highest amount of soluble sugars (53 g kg^?1 fresh weight (f.w.)), mainly glucose and fructose, and, hence the ‘sweetest’ among cherry tomatoes. High‐pigment tomatoes, especially HLY02 and HLY13, showed a soluble sugar content much lower than cherry tomatoes, as expected for industrial, normal‐size tomatoes. Variations in the fructose/glucose ratio, of between 0.68 and 1.48, were evidenced among the different tomato cultivars. Cell wall polysaccharides isolated from whole fresh red‐ripe berries of each cultivar were analysed chemically. The amount of matrix polysaccharides (0.9–3.4 g kg^?1 f.w.) and cellulose (0.16–1.86 g kg^?1 f.w.), as well as their glycosidic composition, showed significant differences among the different cultivars. Cellulose to matrix polysaccharide ratio was highly variable and ranged between 0.06–1.44 and 0.17–0.77 in cherry and high‐pigment tomato cultivars, respectively. CONCLUSION: The differences evidenced in the total soluble sugar and cell wall polysaccharide composition, not only among different types of tomatoes but also different cultivars within the same typology, may play a fundamental role in the quality of tomatoes and deserve further investigations. Copyright © 2008 Society of Chemical Industry     

毛细管气相色谱法测定番茄中的非挥发性有机酸、高级脂肪酸和低分子量糖类

本文提出了应用毛细管气相色谱法(CGC)对番茄内的非挥发性有机酸、高级脂肪酸和低分子量糖类进行测定的方法。番茄样品经匀浆后用水在超声波振荡下提取,减压干燥后, 用羟胺吡啶(2.5mg/ml)先将糖转化为肟,再用硅烷化试剂(BSTFA+1%TMCS)衍生化,然后进行毛细管气相色谱分析。有机酸的测定采取将番茄样品加入H2SO4-CH3OH(10%) 30ml衍生化2h,经萃取、干燥后再进行毛细管气相色谱分析。针对方法的前处理条件、重现性及回收率均进行了探讨。结果显示番茄中糖类主要含有葡萄糖、果糖,酸类主要包括柠檬酸、苹果酸、棕榈酸。此外, 对比不同品种的番茄样品中糖及有机酸含量成分进行了营养对比实验。     

Volatile profile of dehydrated cherry tomato: Influences of osmotic pre-treatment and microwave power

Vegetable flavour is a quality characteristic for consumer acceptability. Sun and air are traditionally used for drying tomatoes; however, the optimal combination of techniques such as osmotic dehydration or microwave-assisted air-drying could lead to high quality self-stable products. The aim of this paper was to study the influence of different process variables on the volatile profile of dehydrated cherry tomato halves. The analysed variables were: air-drying temperature (40 and 55 °C), microwave power (0 and 1 W/g) and previous osmotic dehydration with a 55 Brix binary sucrose solution at 30 °C for 120 min (OD1) or ternary solution of 27.5% sucrose + 10% NaCl (w/w) at 40 °C for 60 min (OD2). Twenty major volatile compounds were identified in fresh tomatoes. Among them, 2-isobutylthiazole and 6-methyl-5-hepten-2-one stand out as impact volatile compounds. Dehydration modified the volatile profile, mainly due to the changes induced in some typical fresh-like tomato compounds, but also due to the generation of five new compounds: 1-butanol, 2-methyl-2-butenal, 3-hydroxy-2-butanone, furfural, acetonitrile, related to Maillard reactions, and the catabolism of carotenoids and polyunsaturated fatty acids. Principal component analysis showed the possibility of obtaining dried cherry tomatoes with different volatile profiles, depending on drying conditions.     

保鲜剂对甜樱桃果实贮藏性的影响研究

以红灯等甜樱桃为试材,探讨自制的甜樱桃专用保鲜剂对甜樱桃贮藏保鲜的效果。试验结果表明,该保鲜剂处理在保持甜樱桃果实营养方面有良好的效果,能够有效地抑制果实的褐变,减少果实腐烂。     

Partial dehydration of cherry tomato at different temperature, and nutritional quality of the products

This study concerns the partial dehydration of cherry tomatoes (Lycopersicon esculentum, var. Shiren) to obtain a product with 25% initial water content. Two kinds of dried tomatoes were obtained using a forced air oven at 40, 60 and 80 °C for different lengths of treatment. The first type was dehydrated after immersion of the fresh tomatoes in an aqueous solution of citric acid, sodium and calcium chloride (10:10:24 g/l); the second was obtained with no pre-treatment. The products were characterised by measuring their CIE L*a*b* colour parameters and levels of l-ascorbic acid, lycopene and β-carotene to evaluate thermal damage during processing under the different conditions. Moreover, water activity and the formation of 5-hydroxymethylfurfural were also determined as an index of sugar heat degradation. Treatment with a dipping solution protected both the nutritional and chemical qualities of the partially dried cherry tomatoes. Temperature was directly related to browning, ascorbic acid loss and HMF formation, while no clear influence could be found for carotenoid degradation.     

Contribution of tomato phenolics to suppression of COX-2 expression in KB cells

Tomatoes, which are consumed worldwide, contain abundant phenolics. The objective of this study was to understand the suppression effect of phenolics in fresh and heated tomatoes on the expression of cyclooxygenase 2 (COX-2). Both small and big tomatoes of fresh or heated (in boiling water for 30 min) treatments were used. Sephadex LH-20 gel was used to separate the noncondensed tannin containing and the condensed tannin containing fractions from the crude phenolic extracts of tomatoes. The condensed tannin containing fraction was rich in condensed tannins and simple phenolics. The noncondensed tannin containing fraction contained abundant nontannin flavans. This study explored the effect of tomato phenolic extracts on the regulation of 12-o-teradecanoylphorbol-13-acetate (TPA)-induced inflammatory responses in KB cells. HPLC showed that tomato phenolic profiles were similar between small and big tomatoes either by fresh or heated treatment. Fresh tomato extracts had 70.8 +/- 4.8% (mean +/- SD) noncondensed tannin containing polyphenols (6.68 +/- 0.09 mg/g dry weight), 27.4 +/- 6.9% condensed tannin containing polyphenols (3.52 +/- 0.24 mg/g dry weight), and 1.7 +/- 0.6% other residues. Instead, heated tomato had 53.3 +/- 4.3% noncondensed tannin containing polyphenols (2.70 +/- 0.20 mg/g dry weight), 24.2 +/- 1.7% condensed tannin containing polyphenols (7.37 +/- 0.03 mg/g dry weight), and 22.5 +/- 4.8% other residues. Cell studies showed that phenolic extracts of heated tomatoes resulted in increased suppression of COX-2 expression compared with that of fresh tomato. Noncondensed tannin containing fraction of fresh tomato greatly suppressed COX-2 expression (P < 0.05) that compared to the negative control, but both noncondensed tannin containing and condensed tannin containing fractions of heated tomatoes showed suppression on COX-2 expression. These results suggest that tomato phenolics may play an important role in the chemoprevention of cancer.