不同干燥方式对橄榄果粉品质的影响

比较微波干燥、热风干燥、真空干燥以及真空冷冻干燥对橄榄果粉外观色泽、物理特性、营养成分及微观结构等品质的影响。结果表明:真空冷冻干燥橄榄果粉色泽较佳,具有较高亮度和最低的红绿度,最接近鲜食橄榄绿色色泽;热风干燥和真空干燥所得果粉吸油性较低,吸湿性较高,热风干燥的果粉堆积密度和溶解度均最高,真空冷冻干燥的果粉堆积密度最低,吸湿率低,复水性、流动性、吸油性和溶解度均较高,微波干燥的果粉含水率最高,复水性、吸湿率、堆积密度、吸油性和溶解度均较低;微波干燥的还原糖、总酸含量损失较小,热风干燥的类黄酮损失较小,真空干燥的总糖和总酚含量损失较小,真空冷冻干燥的蛋白质含量损失较小。扫描电镜观察微观结构发现微波干燥和真空冷冻干燥果粉颗粒间空隙大,组织较光滑完整,皱缩少,热风干燥和真空干燥果粉颗粒间空隙小,部分皱缩。通过主成分分析品质综合得分结果为:真空冷冻干燥>真空干燥>热风干燥>微波干燥。     

响应面法优化复合酶酶解制备可口革囊星虫胶原蛋白抗氧化肽工艺研究

以可口革囊星虫为原料提取胶原蛋白,以总抗氧化能力和超氧阴离子清除率为考察指标,通过单因素实验和响应面法优化复合酶酶解制备可口革囊星虫胶原蛋白抗氧化肽工艺条件。结果表明,选用酶筛选试验中多肽抗氧化活性较高的木瓜蛋白酶、中性蛋白酶、胃蛋白酶和酸性蛋白酶进行单酶和复合酶试验,最佳方案确定为木瓜蛋白酶与中性蛋白酶复合酶解。在单因素实验基础上确定复合酶添加量（U/g）、酶解温度（℃）、酶解pH、酶解时间（h）为自变量,通过响应面法优化并参考实际因素,确定复合酶酶解的最优条件是:复合酶添加量8135 U/g、酶解温度51.6 ℃、酶解pH6.4、酶解时间4.2 h,在此条件下酶解制备的胶原肽总抗氧化能力为(1.333±0.021）μmol/mL,超氧阴离子清除率为78.75%±0.94%。     

福建省4 个果梅主栽品种果实营养品质、香气成分分析与评价

以福建省4 个果梅主栽品种青竹梅、龙眼梅、杭梅和白粉梅为试材,分析测定果实的主要性状和营养成分,包括单果质量、果实大小、VC、总酚、类黄酮、可溶性糖、有机酸、香气组分以及矿质元素含量。结果表明,4 个果梅品种VC、总酚、类黄酮、可溶性糖、有机酸、香气组分以及矿质元素含量存在显著差异。果梅主要可溶性糖为蔗糖,其次为葡萄糖和果糖;主要有机酸为柠檬酸,其次为苹果酸、琥珀酸、乙酸和奎宁酸;4 个果梅品种果实共检测出110 种挥发性物质,包括30 种酯类、26 种醇类、17 种醛类、15 种酮类、7 种酸类以及15 种其他类,其中有26 种物质为4 个品种共有成分,2-己烯醛、己醛、己醇和反式-罗勒烯醇可能是果梅特征香气的重要物质;4 个果梅品种含有较高的K、Ca和Se含量。通过主成分分析提取,得出综合得分品种最高为青竹梅,青竹梅果实挥发性物质相对总含量高于其他3 个品种且综合品质最佳,适宜作为选育果梅良种的育种材料。本研究结果为明确果梅营养价值评价及其在良种选育、生产加工中的合理利用提供理论依据。     

低温贮藏对油㮈果实采后贮藏品质的影响

目的 研究适宜低温贮藏对油?果实采后综合贮藏品质的影响。方法 以室温为对照, 测定采后贮藏期间各项理化指标变化, 评价低温贮藏对油?果实采后贮藏品质的影响。结果 与室温贮藏相比, (4±1) ℃低温贮藏能显著抑制果实采后腐烂率和质量损失率上升, 有效延缓贮藏中后期果实硬度下降和丙二醛含量积累; 可延缓果实贮藏后期可滴定酸、总糖和维生素C含量下降, 维持蔗糖含量。结论 低温贮藏可有效延缓油?果实采后贮藏品质劣变。     

福建10个不同产地‘芙蓉李’果实品质与矿质元素含量的相关性与通径分析

目的 研究福建10个不同产地‘芙蓉李’果实品质与矿质元素含量的关系,分析果实品质与矿质元素含量的地区差异,以及影响各果实品质的主要矿质元素。方法 采集福建10个产地果园的‘芙蓉李’,测定8个品质指标和10种矿质元素含量,利用比较分析、相关分析和通径分析等方法,分析地区间品质和矿质元素含量的差异、相关性和通径系数。结果 不同产地间各果实品质指标、矿质元素含量均存在极显著差异(P<0.01)。相关性分析表明,单果重与N含量呈显著正相关、与Mg含量呈显著负相关,色泽亮度因子L^*与Zn含量呈极显著正相关(r=0.903)、与P含量呈显著正相关(r=0.685),色泽红色因子a^*与Zn呈显著负相关(r=-0.706),色泽黄色因子b^*与Ca含量呈显著正相关(r=0.677)、而与Fe含量呈显著负相关(r=-0.705)。通径分析表明, N对单果重的直接影响最大, P对硬度的直接影响最大, Mn对固酸比的直接影响最大;Zn是对可溶性固形物含量、色泽因子L^*、a^*均具有最大直接影响的元素,Fe是对可滴定酸、色泽因子b^*有最大直接影响的元素,对‘芙蓉李’品质指标直接影响较大的元素还有B、Ca、K等。结论 ‘芙蓉李’果实品质是多种元素共同作用的结果,在生产中应协调好各种矿质元素的配比以提高果实品质,实现优质高效生产。     

温度对李果实采后品质的影响及货架期预测模型建立

目的 研究李果实采后品质变化及建立李果实采后货架期预测模型。方法 本试验设置了3种温度（4、15、25℃）,并定期测定生理生化指标。采用零级动力学模型和一级动力学模型结合Arrhenius方程建立基于品质变化的李果实采后货架期预测模型,并验证模型的预测精确度。结果 低温明显延缓了果皮强度和果肉硬度的下降和果实失重率的上升,同时也延缓了花色苷含量的积累,对总酸含量影响不明显。根据果皮强度、果肉硬度和失重率变化建立货架期预测模型,通过验证发现基于失重率变化的货架期预测模型具有最好的精确度,相对误差值低于10%。结论 货架期预测模型的建立,可快速预测果实剩余货架期,为贮藏和货架提供技术指导。     

Thermogravimetric analysis of longan seed biomass with a two-parallel reactions model

The kinetic analysis of pyrolysis process of longan seed was performed in a thermogravimetric analyzer. All experimental runs were carried out by using an initial sample mass of 15 mg and final temperature of 650 °C under the inert atmosphere of nitrogen. Particle sizes in the range from 0.05–2.1 mm and the heating rates from 5–100 °C/min were employed to investigate their effects on the thermogram and the kinetic parameters. The TG curves generally showed sigmoid shape and displayed one major peak in DTG curve. The main devolatilization of longan seed occurred over the temperature range of 210–330 °C. It was found that heat transfer resistance in a particle could be reduced either by decreasing the size of particle or increasing the heating rate. The thermal decomposition of longan seed could be well described by the two-parallel reactions kinetic model. This analysis of reaction kinetic gave the values of activation energy for the decomposition of the two fractions in the model corresponding closely to those of hemicellulose and lignin.     

Changes in the Content of Organic Acids and Expression Analysis of Citric Acid Accumulation-Related Genes during Fruit Development of Yellow (Passiflora edulis f. flavicarpa) and Purple (Passiflora edulis f. edulis) Passion Fruits

Organic acids are key components that determine the taste and flavor of fruits and play a vital role in maintaining fruit quality and nutritive value. In this study, the fruits of two cultivars of passion fruit Yellow (Passiflora edulis f. flavicarpa) and purple (Passiflora edulis f. edulis) were harvested at five different developmental stages (i.e., fruitlet, green, veraison, near-mature and mature stage) from an orchard located in subtropical region of Fujian Province, China. The contents of six organic acids were quantified using ultra-performance liquid chromatography (UPLC), activities of citric acid related enzymes were determined, and expression levels of genes involved in citric acid metabolism were measured by quantitative real-time PCR (qRT-PCR). The results revealed that citric acid was the predominant organic acid in both cultivars during fruit development. The highest citric acid contents were observed in both cultivars at green stage, which were reduced with fruit maturity. Correlation analysis showed that citrate synthase (CS), cytosolic aconitase (Cyt-ACO) and cytosolic isocitrate dehydrogenase (Cyt-IDH) may be involved in regulating citric acid biosynthesis. Meanwhile, the PeCS2, PeACO4, PeACO5 and PeIDH1 genes may play an important role in regulating the accumulation of citric acid. This study provides new insights for future elucidation of key mechanisms regulating organic acid biosynthesis in passion fruit.     

不同取汁工艺对青竹梅出汁率及品质的影响

目的 探讨不同取汁工艺对青竹梅出汁率及品质的影响。方法 以新鲜青竹梅为实验材料, 研究水浴提取法、超声波辅助提取法和复合酶法对青竹梅出汁率的影响, 对比分析3种方法在最优条件下的出汁率、可溶性固形物、可滴定酸、总糖、类黄酮和总酚等指标差异。结果 水浴提取法最优工艺料液比1?4(g:mL), 水浴温度80 ℃, 水浴时间60 min, 出汁率52.4%; 超声波辅助提取法最优工艺: 料液比1?4(g:mL), 超声波功率140 W, 提取温度60 ℃, 提取时间20 min, 出汁率53.2%; 复合酶解法最优工艺: 果胶酶添加量为0.6%, 纤维素酶添加量为0.2%, 酶解温度40 ℃, 酶解时间90 min, 出汁率66.6%。结论 3种方法均可有效提高青竹梅出汁率, 但复合酶法出汁率最高且综合营养成分提取效果最好。