Delayed harvest reduces quality of raw and roasted macadamia kernels

BACKGROUND: Macadamia integrifolia, M. tetraphylla and their hybrids are cultivated for their edible kernels. Abscised macadamia fruit is gathered from the ground, and harvest intervals vary due to management decisions or unavoidable delays. In this study, macadamia fruit from cultivar HAES 344 was harvested between May and August in three experiments in south‐east Queensland, Australia. Control fruit was dehusked, dried and evaluated immediately, while delayed harvest fruit remained on the ground under trees for periods of 3 and 5 weeks before processing. Whole kernel weight, shoulder damage and weight of pieces were assessed for raw kernels, and kernel colour mottled colour and surface damage were assessed after roasting. RESULTS: Delaying harvest for 3 weeks in experiment 1, and 3 or 5 weeks in experiment 2 reduced whole kernel and increased shoulder damage and weight of pieces. Experiment 3 raw kernel was not affected. After‐roast darkening increased in all experiments, and roasting produced severe mottled colour in one experiment, and severe surface damage in two of three experiments. CONCLUSION: Macadamia kernels may deteriorate rapidly when harvest is delayed, and both raw and roasted kernel quality may be affected. Shorter harvest intervals, preferably less than 3 weeks, will help maintain optimum kernel quality. Copyright © 2008 Society of Chemical Industry     

采摘时间和天气条件对菜豆保鲜品质的影响

以贵阳青棒豆作为试材,采后贮藏在(9±1)℃下,研究了不同采摘时间和天气条件对其贮藏期间失重率、腐烂率、硬度、可溶性固形物含量、呼吸速率、可溶性蛋白质、抗坏血酸、淀粉及色泽的影响。研究发现,在阴天中午采摘时贵阳青棒豆的贮藏和营养品质最佳。      

1-MCP处理对不同采收期阿克苏红富士苹果贮藏品质的影响

以阿克苏红富士苹果为试材,对三个采收期果实进行1-MCP熏蒸处理,通过测定贮藏过程中果实硬度、可滴定酸含量、V_C含量、可溶性固形物含量、失重率等指标,研究1-MCP处理对不同采收期果实低温贮藏下果实品质与生理变化的影响。结果表明:使用1.0μL/L的1-MCP在常温下处理富士苹果24 h,在低温贮藏期间果实呼吸高峰的出现推迟了30 d;至贮藏结束,不同采收期的果实处理组失重率平均低于对照组10%,处理组硬度平均高于对照组0.33 kg·cm^-2,处理组可滴定酸含量平均高于对照组0.16%。1-MCP处理对不同采收期果实在贮藏期间品质的影响差异显著,根据贮藏过程中果实品质的变化情况,中期采摘果实（本文为11月1日）1-MCP处理效果较好,贮藏150 d后果实硬度≥8.66kg·cm^-2,可溶性固形物含量≥14.79%。      

Quality of fresh‐cut products as affected by harvest and postharvest operations

There is a rising demand for fresh‐cut convenience products with high quality and nutritional standards that needs to be met by the fresh‐cut industry. It is well known that harvest and postharvest handling of fresh produce has a paramount impact on its quality and storage, although most of the existing literature has focused on these impacts related only to fresh produce that is destined for the final consumers. Indeed, current harvest methods and postharvest technologies have improved fruit and vegetable handling and distribution processes by slowing down physiological processes and senescence. Nonetheless, these technologies and methods may influence the quality of fresh produce as raw material for fresh‐cut processing as a result of the dynamic responses of fresh produce to handling procedures and treatments. Here, we review the existing literature on the challenges facing the fresh‐cut industry, focusing on the impact of harvest, maturity, and handling of fruit and vegetables on the quality of raw materials, as well as the implications for fresh‐cut products. The review also highlights areas for further research with the aim of enhancing the sensorial, nutritional and biochemical quality of such products. © 2018 Society of Chemical Industry     

Plant metabolites and nutritional quality of vegetables

ABSTRACT:  Vegetables are an important part of the human diet and a major source of biologically active substances such as vitamins, dietary fiber, antioxidants, and cholesterol-lowering compounds. Despite a large amount of information on this topic, the nutritional quality of vegetables has not been defined. Historically, the value of many plant nutrients and health-promoting compounds was discovered by trial and error. By the turn of the century, the application of chromatography, mass spectrometry, infrared spectrometry, and nuclear magnetic resonance allowed quantitative and qualitative measurements of a large number of plant metabolites. Approximately 50000 metabolites have been elucidated in plants, and it is predicted that the final number will exceed 200000. Most of them have unknown function. Metabolites such as carbohydrates, organic and amino acids, vitamins, hormones, flavonoids, phenolics, and glucosinolates are essential for plant growth, development, stress adaptation, and defense. Besides the importance for the plant itself, such metabolites determine the nutritional quality of food, color, taste, smell, antioxidative, anticarcinogenic, antihypertension, anti-inflammatory, antimicrobial, immunostimulating, and cholesterol-lowering properties. This review is focused on major plant metabolites that characterize the nutritional quality of vegetables, and methods of their analysis.     

绿陈茶发酵后主要品质及香气成分的变化

以绿陈茶为原料通过潮水后固体发酵,分析茶叶中主要品质成分及香气成分的变化。结果表明,发酵后,绿陈茶中的茶多酚、儿茶素总量分别下降了52.87%和87.12%,简单儿茶素降低了80.88%,酯型儿茶素降低了90.66%,其中EGCG降幅达92.7%,但没食子酸含量增加了888.72%;绿陈茶中的游离氨基酸总量下降了53.67%,叶绿素下降了27.6%,但可溶性糖及水溶性果胶含量分别增加了53.4%和50.15%,茶黄素、茶红素和茶褐素含量分别增加了33.33%、15.26%和129.3%。发酵后,茶样中的香气物质总含量相较于绿陈茶增加了235.80%,并新增了香叶醇、苯并环庚三烯,但二甲基-2-异丙基苯和1-甲基萘不再检测出,芳樟醇及其氧化产物发生了剧烈的变化。植醇和3-甲基-2丁烯基苯是所有茶样中含量最多的两类香气成分。经感官评定发酵后的茶样具有典型的四川黑茶品质风格特征。      

Antifungal activity of chitosan and its application to control post‐harvest quality and fungal rotting of Tankan citrus fruit (Citrus tankan Hayata)

In this study, the antifungal activity of chitosan A (MW = 92.1 kDa) and B (MW = 357.3 kDa), with 94.2% N‐deacetylation were examined at various concentrations against fungi including Penicillium digitatum, Penicillium italicum, Botrydiplodia lecanidion and Botrytis cinerea. The effectiveness of these chitosans to control the post‐harvest quality of Tankan fruit, a popular sub‐tropical citrus fruit, was investigated. It was found that chitosan, depending on type and concentration, caused 25.0–90.5% growth inhibition on test organisms after 5 days of cultivation at 24 °C. Chitosan treatment significantly reduced (P < 0.05) the percentage decay of Tankan fruit during storage at 24 °C. After 42 days of storage at 13 °C, chitosan‐coated Tankan fruits were firmer, exhibited less decay and weight loss, and showed higher titratable acidity, ascorbic acid, and total soluble solids than the control fruit. Weight loss of Tankan fruits decreased as the concentration of chitosan was increased. On the other hand, chitosan A, regardless of concentration tested, was found to be more effective in retaining the firmness, titratable acidity and water content, total solid content and ascorbic acid content of Tankan fruits than chitosan B. Copyright © 2006 Society of Chemical Industry     

Delayed harvest and cold storage period influence ethylene production,fruit firmness and quality of ‘Cripps Pink’ apple

The effects of harvest date and cold storage period on ethylene production, fruit firmness and quality of ‘Cripps Pink’ apple were investigated. Fruit were harvested from Perth Hills and Donnybrook (Western Australia) at commercial maturity (CM), 2, 4 and 6 weeks after CM prior to 0, 45, 90 and 135 days cold storage in 2003 and 2004. Delayed harvest significantly increased ethylene production, CIE values a* and C* at both locations in 2 years. Delayed harvest and extended cold storage period increased the internal ethylene production and reduced fruit firmness, soluble solids concentration: titratable acidity (SSC:TA) ratio and reduced CIE values L*, b*, h° during both years and locations. Fruit harvested 2 weeks after CM can be cold‐stored for 90 days with acceptable fruit quality. If the fruit is intended to be sold fresh immediately in local markets, the harvest can be delayed up to 6 weeks after CM to harness substantially improved fruit colour with acceptable fruit quality.     

The effect of delayed harvest on moisture content,insect damage,moulds and aflatoxin contamination of maize in Mayuge district of Uganda

Field drying is a traditional practice carried out by farmers in Uganda and it is one of those practices reported to affect the postharvest quality of maize. A study was therefore conducted to establish the effects of delayed harvest on moisture content, insect damage, moulds and aflatoxin contamination of maize in Mayuge district. Sixteen farmers were selected from Bayitambogwe sub‐county, eight from each of the villages of Bugodi and Musita. Maize was sampled from each farmer's field in 2003B and 2004A seasons at harvest stages of physiological maturity and after delayed harvest for 1, 2, 3 and 4 weeks. Each sample was analysed for mould incidence, moisture content, insect damage and aflatoxin contamination. In each season, mould incidence, insect damage and aflatoxin levels significantly (P < 0.05) increased with delayed time of harvest. Moisture content reduced with delayed harvest time but the maize did not dry to the required safe storage moisture content of ?15%. Seasonal effects were only significant for moisture content: the 2003B crop had consistently lower moisture content than 2004A crop. These results indicate that, for improved harvest quality of maize, farmers should harvest no later than 3 weeks after maize has attained physiological maturity. Copyright © 2005 Society of Chemical Industry     

Protein quality and energy density of green peas as influenced by seed size and time of harvest

Green peas (Pisum sativum L) were harvested at three different time points—3 days apart—and subsequently sorted into four fractions according to seed size (diameter > 10.2 mm; 10.2–8.75 mm; 8.75–8.2 mm and 8.2–6.0 mm). Three varieties from two years were investigated. The study comprised a total of 31 green pea samples. The average protein content of the samples was 276 g kg^?1 DM with relatively low variation (SE = 5.7). Protein content was highest in the smallest seeds. The average energy content was 18.6 MJ kg^?1DM. Dietary fibre content was 226 g kg^?1 DM, the major part (77%) as insoluble fibre. Seeds of early harvest and seeds with the smallest diameter had the lowest fibre (IDF and TDF) content and at the same time the highest energy digestibility. The average energy digestibility was 83.2%. Protein digestibility was relatively high (average 92.1%), while biological value (BV) and net protein utilisation (NPU) were moderate to low (60.6% and 55.8% respectively) due to low contents of the essential amino acids (g per 16 g N), especially tryptophan, methionine + cystine and lysine. Contents of lysine, tryptophan and methionine + cystine were more than 20% higher in the smallest seeds compared to the larger seeds. Similar differences were observed in seeds of late harvest as compared with seeds of early harvest. Correlation coefficients revealed a strong positive correlation between lysine, tryptophan and methionine + cystine content and the biological value of green pea protein. The three varieties investigated showed no differences in the chemical parameters although small differences in BV and NPU were observed.     

Influence of nutrient solutions in an open‐field soilless system on the quality characteristics and shelf life of fresh‐cut red and green lettuces (Lactuca sativa L.) in different seasons

BACKGROUND: Little information is available about the impact of nutrient solution ion concentration on quality characteristics and shelf life of fresh‐cut lettuce grown in soilless systems in open field. Three lettuce genotypes, lollo rosso and red oak leaf as red‐leafed genotypes and butterhead as green‐leafed genotype, were studied. The influence of three nutrient solutions with low, medium and high ion concentrations, which varied in the macroanion (NO$_{3}^{-}$ ) and macrocations (K⁺, Ca²⁺ and NH$_{4}^{+}$ ), were compared in summer and winter. RESULTS: The nutrient solutions evaluated in this study for the production of lettuce in a soilless system did not strongly influence the quality characteristics of the raw material. When the ion concentration of the nutrient solution was increased, fresh weight decreased, although it depended on the genotype and season. Maturity index and dry matter content varied with the season but independently of the nutrient solution. In summer, maturity index was higher and dry matter lower than in winter. Initial texture and visual quality were not influenced by the nutrient solution. Medium ion concentration provided the highest content of vitamin C and phenolic compounds. Our observations pointed out that the genotype had a strong influence on the shelf life of the fresh‐cut product with minor differences among nutrient solutions. In general, red‐leafed lettuces showed the highest antioxidant content, helping the maintenance of sensory characteristics throughout storage. CONCLUSION: The combination of optimal nutrient solution ion concentration and suitable cultivar is considered essential to ensure lettuce post‐cutting life. Copyright © 2012 Society of Chemical Industry     

不同采收期不同品种莲藕的营养品质变化规律及评价

目的 探究不同采收期不同品种莲藕的营养成分和活性成分的变化规律。方法 选取5个采收期的4个品种莲藕,测定蛋白质、淀粉等指标。采用主成分分析和聚类分析进行综合评价,并建立莲藕品质评价模型。结果 在采收期内,莲藕淀粉含量呈现先上升后下降再上升的趋势,可溶性糖的变化趋势与其相反;总酚含量整体呈现先上升后下降的趋势;蛋白质、膳食纤维等指标呈现不同的变化规律。主成分分析法提取出PC1、PC2、PC3 3个主成分因子,特征值依次为2.274、1.933、1.023,累积方差贡献率达87.170%。不溶性膳食纤维、可溶性膳食纤维、可溶性总糖、淀粉、总酚和总黄酮6个指标可以用来综合评价莲藕营养品质。综合评价发现, 9月采收的八月粉,10月的鄂莲6号,2月的鄂莲10号和鄂莲11号,营养品质较好,优于其他采收期。3月采收的4个品种莲藕的综合营养品质较低。结论 在采收期内, 4个品种莲藕的营养物质动态规律存在一定差异。基于主成分分析和聚类分析的分析方法能够科学评价不同采收期莲藕的综合营养品质,为莲藕育种、加工等提供支撑。     

植物多糖在低盐低脂肉制品中的应用

食用高盐高脂肉制品不利于人体健康,低盐低脂已成为肉制品发展趋势。植物多糖是一种天然的高分子化合物,将其添加到肉制品中可以改变肉体系的凝胶、持水、乳化能力等特性,提高肉制品品质（质构、保水性等）、改善感官品质、促进健康等。本文系统总结和归纳植物多糖在肉制品中的应用研究现状,梳理植物多糖在肉类工业中的应用前景,以期为肉类工业中更好地应用植物多糖提供理论指导。     

酵母菌和乳酸菌发酵老面团过程中对可溶性糖的代谢

采用Saccharomyces cerevisiae CGMCC2.0562和/或Lactobacillus brevis CGMCC1.0579纯菌接种发酵老面团,研究老面团发酵过程中微生物对可溶性糖的代谢作用。本实验确定了高效液相色谱(HPLC)-蒸发光散射检测器(ELSD)检测老面团中可溶性糖(麦芽糖、蔗糖、葡萄糖和果糖)的方法为流动相乙腈/水(70∶30,V/V),流速1.0mL/min,柱温25℃;ELSD漂移管温度83.5℃,载气空气流速2.2L/min。结果显示,S.cerevisiae2.0562能快速消耗麦芽糖、蔗糖和葡萄糖,对果糖的消耗较慢;接种单一L.brevis1.0579时,麦芽糖、葡萄糖的浓度增大,总体而言蔗糖浓度呈下降趋势,果糖呈上升趋势;接种S.cerevisiae2.0562和L.brevis1.0579时,麦芽糖、葡萄糖和果糖的浓度前几个小时降低,随后开始增加,而乳酸菌的存在减慢了酵母菌对蔗糖的消耗。由此看出接种不同菌种对可溶性糖的消耗不同,所以对老面团特性及代谢物的产生会有不同的影响,最终将影响馒头的品质。     

基于稀土元素指纹分析判别普洱古树茶和台地茶的研究

普洱茶根据不同来源分为古树茶和台地茶。古树茶被认为是一种有别于台地茶的茶,具有特殊的香气和品质。本研究为探讨基于稀土元素指纹对普洱茶不同来源判别的有效性,找寻表征判别特性的元素指标,采用电感耦合等离子体发射光谱法（ICP-MS）测定云南省西双版纳州代表性普洱茶古树茶和台地茶中的15种稀土元素（La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Y、Er、Tm、Yb、Lu和Sc）含量,对数据进行方差分析、主成分分析和判别分析,筛选出4个有效判别指标La、Ce、Eu和Sc,分别建立普洱茶古树茶和台地茶的判别模型,产地检验判别率为94.4%,交叉检验判别率83.3%;身份判别检验率为100%,交叉检验判别率91.65%。利用不同来源的普洱茶稀土含量差异,结合稀土元素指纹技术判别普洱古树茶和台地茶的分类方法是可行性的     

HPLC测定植物染纺织品中姜黄素及其同系物

建立了HPLC同时测定植物染纺织品中姜黄素、去甲氧基姜黄素和双去甲氧基姜黄素含量的方法.采用Agilent C18色谱柱(4.6 mm×250 mm,5μm);流动相:乙腈-9.6％乙酸(48:52);柱温:30℃;流速:1.0 ml/min;紫外检测波长:425 nm.结果表明3种姜黄素线性良好,线性相关系数r在0....