Ripening Associated Phytochemical Changes in Mangos (Mangifera indica) Following Thermal Quarantine and Low-Temperature Storage

ABSTRACT: Fresh mangos entering the United States must be subjected to a thermal quarantine treatment to eliminate invasive pests, commonly followed by cold storage to extend shelf-life. Changes in phytochemicals and their resultant antioxidant capacity after such treatments are unknown. These studies evaluated mature, green mangos subjected to a simulated quarantine treatment using hot water immersion at 50°C for 60 min and subsequent storage at 5°C and 20°C against their respective controls. Fruit held at 5°C were transferred to 20°C after 8 d of storage to complete ripening, whereby symptoms of chill injury were observed. Phytochemical, antioxidant capacity, and quality parameters were then assessed every 4 d as the fruit ripened over the next 20 d. Storage temperature during ripening and not the hot water treatment was the major factor contributing to changes in polyphenolic content, with antioxidant capacity unaffected by either postharvest treatments or ripening. Major polyphenolics identified were free gallic acid and 4 gallotannins that collectively increased in concentration by 34% as the fruit ripened, also independent of postharvest and storage treatments. Carotenoid concentrations were highest in hot water-treated fruit stored at 20°C, whereas storage at 5°C initially delayed ripening. Despite appreciable differences in fruit quality during quarantine treatment or low temperature storage, only minor differences in antioxidant phytochemicals were observed.     

Demethylation of Pectic Substances: Relationship to Methylesterase Activity during Brine Storage of Cherries

Residual pectin methylesterase activity (60% of initial activity) was present in cherry fruit stored 12 mo in brine. The specific activity of pectin methylesterase increased during the first 4 mo (195% of initial specific activity) but remained relatively stable thereafter. Methanol concentration increased (+144.5%) indicating that pectic substances underwent continuous demethylation during 12 mo storage. Pectin deesterification was probably of enzymatic origin since notable chemical deesterification occurred only at a pH lower than that found in fruit during storage. Residual pectin methylesterase activity introduces the possibility of improving fruit texture by manipulating physico-chemical conditions prior to blanching and candying.     

Relationship between Pectic Substances and Strand Separation of Cooked Spaghetti Squash--Part 2. Changes in Firmness,Histological Structure and Pectic Substances during Soaking in Pectin Extractants

The flesh of spaghetti squash separates into strands when cooked. The purpose of this paper is to investigate the cause of strand separation （during cooking） by soaking for 24 h at 35 ℃ in solutions with three kinds of pectin extractant. The changes in strand separation, firmness, histological structure and the pectin of flesh during soaking in 0.01 N HCI solution （pH 2.0）, 0.035 M ammonium oxalate solution （pH 4.0） or 2% sodium hexametaphosphate solution （pH 4.0） were investigated. When flesh was soaked in the HCI solution, the separation into strands and removal of calcium and magnesium were greater than that soaked in other pectin extractants. High methoxyl pectin was extracted by soaking in HC1 solution （pH 2.0） due to removal of polyvalent cations. This result shows that high methoxyl pectin glues strands together in the flesh of spaghetti squash. The shape of the cells which constituted strands was round; on the other hand, that of cells surrounded strands was elongated. When cooked in boiling water or soaked at pH 2.0, the shape of the former cells was maintained, but the latter cells, which contributed to adhesion between strands, broke down. Thus, the flesh separated into strands. When flesh was boiled for 15-30 min, pectin degraded and dissolved in the cooking solution; consequently, the flesh separated into strands and also the middle lamella of cell walls of strands separated. However, pectin remaining in strands maintained their crispness.     

纳豆生产及冷藏过程中营养成分和生物活性物质变化

为探讨纳豆生产及冷藏过程中营养物质和生物活性成分的变化,以纳豆菌为菌种、以小粒豆为原料进行发酵,通过采集不同时期样品,测定蛋白质、脂肪、可溶性总糖、活菌数、纳豆激酶、蛋白酶、氨基酸态氮及大豆异黄酮等含量或活力指标,研究其在生产及冷藏阶段变化规律。结果表明,小粒豆经过发酵后大部分营养物质含量、生物活性物质活力均有不同程度的提高,但在冷藏阶段各指标出现不同程度的变化。其中以冷藏3 d时蛋白质、氨基酸态氮含量、纳豆激酶、蛋白酶活力最高,分别为（44.81±0.01）%、（0.57±0.05）g/100 g、（3 875±105）IU/g 和（919.75±24.71）U/g,同时在冷藏第3天时,生物活性高的苷元型大豆异黄酮占大豆异黄酮总量比例最高为33.5%,随着冷藏时间的延长,纳豆大部分指标出现下降趋势,其营养保健功效随之降低,综合评价认为冷藏期3 d内纳豆可保持较高的活性成分。     

Changes in Tyramine during Chorizo-Sausage Ripening

The changes in tyramine and several parameters (nitrite and nitrate content, pH value, dry matter, total nitrogen and fatty material) was followed during chorizo-sausage ripening. Tyramine concentrations increased significantly during the fermentation stage and underwent small variations during the drying phase. A relationship between the contents of this amine and the pH of the sausage was observed.     

鳗鱼鲞冷藏过程中油脂氧化及挥发性物质的变化

为研究家庭冷藏条件下鳗鱼鲞油脂氧化和风味衰减情况,将成熟鳗鱼鲞在1～7℃(模拟家庭冰箱)冷藏4个月,测定其在冷藏期内过氧化值(peroxide value,POV)、硫代巴比妥酸(thiobarbituric acid,TBA)值和脂肪酸、风味成分的组成及相对含量变化并结合相关性分析研究冷藏期内鳗鱼鲞油脂和风味物质变化...     

蓝莓贮后货架期间生理品质与挥发性物质的变化

为了探讨自发气调结合冰温贮藏蓝莓果实的贮后货架效果,研究不同处理的两个品种蓝莓（伯克利（Berkeley）和北陆（Northland））冰温贮藏40 d后10 ℃货架期间果实品质、生理指标以及挥发性物质的变化规律。结果表明,两个品种果实贮后货架期间具有相似的变化规律：自发气调结合冰温处理能够有效延缓果实硬度和VC含量的下降,抑制丙二醛含量的增加,并维持了较高的谷胱甘肽含量、过氧化物酶和超氧化歧化酶活性,有效控制了果实质量的损失与腐烂,延长了果实贮后货架寿命。蓝莓果实在贮后货架期间醇类和酯类化合物相对含量呈上升趋势,萜类相对含量呈下降趋势,相同货架期的自发气调结合冰温处理果实醇类和酯类化合物相对含量则高于冰温处理,而萜类化合物相对含量低于冰温处理。     

卤牛肉贮藏过程中气味活性化合物变化及异味分析

采用吹扫捕集-热脱附-气相色谱-嗅闻-质谱联用技术、气味活性值研究卤牛肉常温贮藏期间（0、3、6、9、12 个月）气味活性化合物的变化情况,并结合感官评价综合分析异味相关的特征化合物。结果表明：共有52 种气味活性值不小于0.1的气味活性化合物,其中醛类物质最多（13 种）;醛类和醇类所占比例较高,分别为34.53%～70.55%和27.72%～57.91%。贮藏期间卤牛肉色泽变暗,弹性降低,贮藏后期香气逐渐减弱,异味明显加重,可接受度降低,主成分分析可较好地区分不同贮藏时间的卤牛肉样品。相关性分析发现,分别有16、12 种气味活性化合物与风味感官评分和贮藏时间显著相关,结合气相色谱-嗅闻鉴定,1-辛烯-3-醇、庚醛、正辛醛、壬醛、癸醛、反,反-2,4-癸二烯醛、2-壬酮、辛酸可能是产生异味的主要物质。     

The Effects of Harvest Maturity on Storage Quality and Sucrose-Metabolizing Enzymes During Banana Ripening

Mature green “Baxi” banana (Musa spp. AAA Group, Cavendish) fruits were harvested at 60% and 80% maturity stages. In order to evaluate the effects of harvesting at different maturity stages on storage quality and changes in sucrose-metabolizing enzymes, fruit firmness, disease index, contents of starch, and total soluble sugars were determined, and enzyme activities associated with sucrose metabolism was investigated under natural and accelerated (treated with ethylene) ripening conditions. In fruit treated with ethylene, changes in flesh firmness, total sugar content, starch content, disease index, and activity of sucrose phosphate synthase (SPS), sucrose synthase (SS), acid invertase (AI), and neutral invertase (NI) were accelerated dramatically compared with untreated fruit with both 60% and 80% maturity. When fruit ripened under natural conditions, the changes in firmness, disease index, starch content, total sugar content, SPS activity, SS, AI, and NI activity in fruit with 80% maturity were significantly faster than those in fruit with 60% maturity. On the contrary, when fruit ripened under accelerated conditions, no significant differences in firmness, sugar, starch, disease index, SPS, SS, AI, and NI were observed between fruit harvested at 60% or 80% maturity. It is suggested that storage quality and sucrose-metabolizing enzymes of banana fruit stored under natural conditions are related to harvest maturity stage; storage quality of fruit with lower harvest maturity is better than fruit with higher maturity. However, when fruit ripening is accelerated by ethylene, the harvest maturity stage has no influence on storage quality and changes in sucrose-metabolizing enzymes.     

桑果发育期生物活性物质含量及抗氧化酶活性的变化

本研究探讨桑果发育期生物活性物质及抗氧化酶活性的变化规律。以3龄和5龄桑树果实为材料,研究果实发育期总酚、总黄酮、酚酸、单宁、叶绿素及类胡萝卜素、花色素苷、可溶性糖等生物活性物质及总抗氧化能力、抗氧化酶活性的变化。结果表明,桑果在发育成熟过程中,果肉内总酚、总黄酮、酚酸、单宁、花色素苷和可溶性糖含量逐渐升高,叶绿素a含量逐渐下降,叶绿素b和类胡萝卜素含量先上升后下降;整个发育期,3龄树桑果果肉总黄酮和酚酸含量高于5龄树桑果,但总酚、单宁和类胡萝卜素含量则低于5龄树桑果。果肉内的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和苯丙氨酸解氨酶(PAL)活性先下降后上升,过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性逐渐降低,总抗氧化能力逐渐上升;整个发育期,3龄树桑果果肉内的SOD、CAT和PAL酶活性高于5龄树桑果,但APX酶活性低于5龄树桑果,5龄树桑果果肉的总抗氧化能力高于3龄树桑果。因此,桑果果肉中生物活性物质及抗氧化酶活性变化规律与果实成熟度、树龄大小有关。在桑果发育过程中,桑果果肉的总抗氧化能力不断提高,在花后第25 d达到最高。树龄越大的桑果总抗氧化能力比越强。     

Compositional Changes in Mango Fruit During Ripening at Different Storage Temperatures

Chemical changes in Haden, Irwin, Kent, and Keitt mangos stored at 16-28°C and 85-90% RH were followed to determine the optimum storage and ripening conditions. Weight loss was slightly higher at 25° and 28°C than at 16-22°C. Breakdown in acidity during ripening was slower at 16°C. Vitamin C showed two basic trends; a general decrease as in Haden, Irwin, and Keitt or a steady increase as in Kent. Total and β-carotenoids were significantly higher at 22-28°C than at 16-20°C. No significant differences were observed with respect to carbohydrate and soluble solids content. However, sucrose increased spectacularly at all temperatures contributing most to the increase in sweetness. The pattern of chemical changes were strikingly similar in all the varieties. Temperatures of 20-22°C and 85-90% RH are recommended for storage and ripening of mangos to obtain sufficiently acceptable quality attributes.     

Fynbo Cheese NaCl and KCl Changes during Ripening

In a model study we assumed that the cheese is a homogeneous solid with nonuniform initial concentration distributions, cheese surfaces are rendered impermeable after brining, and the generalized Fick's law form is valid for expressing the diffusive fluxes of solutes. NaCl and KCl concentrations at selected positions during distribution in Fynbo cheese kept at 12°C, after salting 10 hr in a brine of 100 g NaCl/L and 100 g KCl/L at the same temperature, were determined experimentally and compared with predicted values with the model at different storage times up to 30 days. Homogeneous distribution of solutes was reached at 20 days ripening, as predicted by the model and verified experimentally.     

Hindrance of Hemicellulose and Cellulose Hydrolysis by Pectic Substances

Treating the tissue of the grapefruit segment membrane with pectinase and cellulase decreased the content of xylose and glucose significantly more than the sum of the separate effects. The synergistic effect obtained by the combination of pectinase and cellulase showed that the pectic substance sterically masked the hemicellulose and cellulose. Breaking down the barrier of the pectic substance with pectinase allowed a significant increase in the hydrolysis of the hemicellulose and cellulose. Preparation of alchol-insoluble solids from fresh tissue modified the structure of the pectin in the cell wall and prevented its steric hindrance to breakdown of hemicellulose and cellulase. Extraction of pectic substances from the tissue by NaOH greatly increased cellulose hydrolysis by cellulase.     

对腐乳后酵过程中一些成分变化的研究

该文对腐乳在后酵过程中的粘度、主要作用酶活力、酸度、氨基酸态氮和总酯的含量变化进行了研究，发现腐乳质构的变化主要发生在后酵40d内；前期培菌时形成的皮膜具有一定的渗透性，使汤料和坯体中的小分子物质可以进行质的传递；由于不同发酵阶段生成的不同中问产物的影响，使3种主要作用酶呈现出不同的活力。     

Ripening of Apples during Storage I.—Introduction

The literature describing the respiration climacteric and some related processes in apples is discussed, with particular attention to implications for commercial storage practice.     

Gamma Radiation Effects on the Pectic Substances in Citrus Fruits

SUMMARY— Exposure of citrus fruits to gamma radiation at doses of 150 and 300 krad increased the water- and oxalate-soluble pectins and decreased the protopectin in component parts of Valencia oranges and Duncan grapefruit. The quantities of water-soluble pectin and protopectin in the peel and membrane were affected the most by irradiation. Degradation of the pectins as measured by jelly grade increased in all components of the irradiated fruits. The greatest decrease in jelly grade occurred in the March samples when the Brix/acid ratio was least. Methoxyl contents of the pectins from the peel of oranges and grapefruit decreased, while this characteristic decreased only slightly in pectins from the membrane of irradiated fruits. Pectinesterase activity in the peel of both oranges and grapefruit decreased with increased dosages, while the activity in the membrane of both fruits increased.     

Determination of Chlorophylls in Kiwi Fruit and Their Changes during Ripening

Chlorophylls were separated into a and b compounds by thin-layer chromatography and determined using a dual-wavelength chromato-scanner. A linear relationship existed in the range 0.1-1.0 μg for chlorophyll a (chla) and 0.1-0.7 μg for chlorophyll b (chlb). The recoveries of chia and chlb when added to kiwi fruit were 79.4% and 99.5%, respectively. Total chla+ chlb contents of four cultivars of kiwi fruit (Abbott, Bruno, Hayward and Monty) were 2000-3000 μg/ 100g at the beginning of growth, but decreased to about 1000 μg after four months. This decrease was mainly due to a decrease in chla. Total chlorophyll content decreased gradually during post-harvest ripening.