Postharvest Gibberellin and Heat Treatment Effects on Polyamines, Abscisic Acid and Firmness in Lemons

Lemons at two ripening stages were vacuum-infiltrated with 100 ppm of gibberellin A₃ (GA₃) or heat-treated at 45°C, and then stored at 15°C for 3 wk. Both treatments increased fruit firmness either in stage 1 or in stage 2. Also, the levels of free putrescine and spermidine in the skin were higher in treated lemons than in controls but spermine concentration did not show significant differences, in fruits of either stage. GA₃ treatment was the most effective in retarding the color change during storage, especially in stage 1 fruits, which was related to the lowest levels of abscisic acid found.     

Naringinase Immobilization in Packaging Films for Reducing Naringin Concentration in Grapefruit Juice

Naringin, a bitter compound in citrus, may be converted to a nonbitter form by enzymic hydrolysis. Our objective was to determine the feasibility of immobilizing naringinase in a food contact approved packaging film. Naringinase from Penicillium sp. was immobilized in cellulose acetate films with up to 23% efficiency at 7°C. Kinetic studies showed that the free enzyme had an optimum pH=3.5 and the immobilized enzyme pH=4.0. Activation energy decreased upon immobilization (from 14.2 to 11.0 Kcal/mol), thus providing an increased catalytic efficiency for immobilized naringinase. The Michaelis constant for immobilized naringinase (K_m=2.1 mM) was lower than for free enzyme (K_mm=3.6 mM). Keeping films under dry storage for 1 mo at room temperature did not cause decreased enzyme activity. A film area/volume ratio (cm²/mL of 10° Brix grapefruit juice) of 7.2 hydrolyzed 60% of the naringin in 15 days at 7°C.     

高效液相色谱法测定柑橘中的柠檬苦素类似物

建立了同时测定柑橘中柠檬苦素和诺米林2种苷元的高效液相色谱方法。色谱柱为Phenomenex C18(250mm×4.6mm,5μm),流动相为体积分数45%乙腈,流速为1.0mL/min,柱温为25℃,检测波长在210nm。经考察该方法可行性强,柠檬苦素和诺米林的平均回收率分别99.91%和98.28%,RSD分别为2.55%和2.30%。因此用该法测定了柑橘中的柠檬苦素和诺米林的含量,并取得了理想的结果。     

柑橘籽油理化特性及脂肪酸组成研究

利用索氏抽提法从3种柑橘籽中提取油脂,并对柑橘籽油的理化特性进行了测定。利用气相色谱-质谱(GC-MS)联用技术对3种柑橘籽油的脂肪酸组成进行了分析和鉴定,每种柑橘籽油都分析鉴定出了10种脂肪酸,其中主要成分为亚油酸和油酸。柑橘籽油具有较高的营养价值,作为新油源具有一定的开发前景。     

果蔬中农药残留分析检测技术的发展

研究了果蔬中农药残留分析检测技术的发展以及应用现状,探讨了我国果蔬生产加工中存在的问题。     

采后橘油诱导及振动胁迫对贮藏期锦橙果皮油胞病的影响

以果皮塌陷指数和变色指数为测定指标,研究橘油及振动胁迫处理对锦橙果皮油胞病的影响。结果表明：随橘油体积分数增大果皮油胞病逐渐加重,并以100%橘油处理对锦橙果皮油胞病的诱导效果最明显;锦橙果皮油胞病发病程度随着振动胁迫强度增大而加重,其中500r/min的诱导效果最显著。另外,在橘油和振动胁迫处理后的果实在不同温度下贮藏时,发现20℃贮藏的锦橙果皮油胞病最为严重,0℃冷害温度也能加剧果实油胞病的发生,5℃贮藏的锦橙果皮油胞病最轻微。研究结果为进一步研究柑橘油胞病的发生机理及防控措施提供理论依据。     

柑橘皮中果胶酯酶的生物学特性研究

研究了柑橘皮中的果胶酯酶的生物学特性。用盐析法从新鲜柑橘皮中提取果胶酯酶粗酶液,用pH-stat法测定果胶酯酶的活力。结果表明,该柑橘皮中的果胶酯酶的最适温度在50℃左右,且对热稳定性好,其最适pH在8左右。     

Evaluating the in vitro bioaccessibility of phenolics and antioxidant activity during consumption of dried fruits with nuts

Dried fruits and nuts are considered as healthy snacks and they are often consumed together in the Turkish diet. In order to investigate the effect of codigestion of dried fruits (figs, apricots, raisins) together with nuts (almonds, walnuts, hazelnuts), total phenolics (TP) and total antioxidant capacity (TAC) have been evaluated spectrophotometrically at different phases of simulated gastrointestinal (GI) digestion, using an in vitro model. TP, ABTS and CUPRAC results revealed that for all fruit–nut mixtures, the amount recovered in the dialyzed fraction was lower than the recovery of fruits or nuts alone, indicating an antagonistic effect. On the other hand, DPPH results showed that for fig–walnut, fig–hazelnut and apricot–hazelnut mixtures the quantity recovered in the dialyzed fractions were 35–107% higher than the recovery of fruits or nuts alone, representing a synergistic effect. Similarly, FRAP results also demonstrated a synergistic effect in case of fig–walnut, apricot–walnut and apricot–hazelnut mixtures (10–74% higher recovery). Current study provides valuable insights into the changes taking place during in vitro GI digestion of dried fruits and nuts.     

商业橘皮果胶与大豆果胶流变性质的比较

通过流变学方法对商业橘皮果胶及大豆果胶溶液黏度及凝胶过程进行分析。结果表明：相同条件下,商业橘皮果胶的黏度高于大豆果胶;在形成凝胶过程中,商业橘皮果胶凝胶体系储能模量要远高于大豆果胶。果胶质量浓度为2 g/100 mL、蔗糖添加量为55、60 g/100 mL,葡萄糖酸内酯（D-glucono-δ-lactone,GDL）添加量为3、4 g/100 mL的商业橘皮果胶与相同条件下的大豆果胶储能模量差异不大;通过加入蔗糖及GDL或提高大豆果胶质量浓度,可明显提高大豆果胶凝胶体系的储能模量,增加大豆果胶的凝胶强度。     

白檀果实含油率及其油脂脂肪酸含量测定的近红外光谱模型构建

为快速、无损检测白檀果实的含油率及其油脂各脂肪酸含量,采用DA 7200型近红外分析仪采集115份白檀果实的光谱数据。采用标准正态变量转换法(SNV)、乘积分散校正法(MSC)、卷积平滑法(SG)、一阶导数(FDE)、二阶导数(SDE)以及多种方式相结合对原始光谱进行预处理,对比不同预处理方法的效果,选择最佳预处理方法,在此基础上,结合偏最小二乘法(PLS)和主成分回归分析(PCR)建立含油率及各脂肪酸含量的预测模型,比较不同模型的交互验证决定系数(RCV)和交互验证标准偏差(RMSECV),确定最佳模型,同时结合化学法的测定结果进行模型外部验证。结果表明：白檀果实含油率、棕榈酸含量、油酸含量的最佳建模方法为PLS与SG+FDE预处理,硬脂酸含量为PLS与SNV+SDE预处理,亚油酸含量为PLS与MSC+SDE预处理,亚麻酸含量为PLS与FDE预处理;模型校验结果表明,近红外光谱法可以用于白檀果实含油率和各脂肪酸含量的测定,其含油率和亚麻酸、亚油酸、硬脂酸、棕榈酸、油酸含量的定标外部验证系数分别为0.960 2、0.727 8、0.909 1、0.709 8、0.903 7和0.912...