处理工艺对四种速冻蔬菜品质的影响

以加工后样品内维生素C(Vc)和可溶性固形物(total soluble solid,TSS)剩余含量为评价指标,分析速冻加工过程中切分大小、漂烫和速冻速率对速冻样品蔬菜(马铃薯、胡萝卜、西兰花和洋葱)品质的影响。研究结果表明:速冻速率在一定范围内对蔬菜Vc和TSS含量无明显影响;切块较大可有效保持蔬菜中的Vc和TSS;速冻前的漂烫过程明显增大了胡萝卜和洋葱Vc和TSS的损失,而马铃薯和西兰花则更适合于漂烫后再速冻的加工方式。     

Thermal Inactivation Kinetics of Peroxidase and Lipoxygenase from Broccoli, Green Asparagus and Carrots

ABSTRACT: Thewermal inactivation curves for peroxidase (POD) and lipoxygenase (LOX) in broccoli (florets), green asparagus (tip and stem), and carrots (cortex and core) extracts were determined in the range of 70 to 95 °C for 0 to 600 s. The capillary tube method was used to obtain quasi-isothermal conditions. The kinetics of both enzymes showed a biphasic first-order model, while at 70 °C, LOX in asparagus showed a monophasic first-order behavior. LOX activity was not detected for carrots. Kinetic parameters, k and Ea , were determined for heat-labile and heatresistant isoenzyme fractions. Additionally, initial and residual activities for both enzymes within tissue sections showed a different distribution and heat stability.     

Vacuum-steam pulsed blanching: An emerging method to enhance texture softening,drying behavior and physicochemical properties of Cornus officinalis

Vacuum steam pulsed blanching (VSPB) was employed as a novel blanching technology on Cornus officinalis to soften the tissue for subsequent coring and dehydration. The current work aims to explore its effect on mass transfer behavior, PPO inactivation, drying characteristics, physicochemical properties, antioxidant capacity, and microstructure of C. officinalis. Results showed that VSPB increased water loss, decreased solid gain, and increased weight reduction with increased blanching cycles. Besides, VSPB significantly changed physical properties and extensively reduced drying time which was attributed to the cell wall components dissolving and cell turgor pressure decreasing, also verified by observing microstructure alteration. PPO was completely denatured after blanching in 6 cycles, but phenolic compounds were still diffused or degraded. Notably, the content of flavonoids and antioxidant capacity significantly increased compared to fresh samples probably due to increased extractability caused by the disrupting cell structure. Besides, the carotenoids and ascorbic acid could be well preserved.     

Polyphenol oxidase inactivation and vitamin C degradation kinetics of Fuji apple quarters by high humidity air impingement blanching

In this study, polyphenol oxidase (PPO) and vitamin C were used as the indicators of enzymes and nutrients to evaluate the apple quality during high humidity air impingement blanching (HHAIB) process. The PPO can be completely inactivated within 7 min at 90–120 °C and can retain relatively more vitamin C in the case of PPO fully inactivation. PPO inactivation followed zero‐order kinetics model at 90 and 100 °C, and followed first‐order fraction model at 110 and 120 °C. Activation energy (E_a) of PPO inactivation was between 11.61 and 13.66 kJ mol^?1 by Arrhenius equation. Vitamin C degradation under all processing temperatures was well described by first‐order model and its E_a value was 26.69 kJ mol^?1. Therefore, the HHAIB process was proved to be an effective pretreatment for Fuji apple quarters to inactivate PPO fast and meanwhile to maintain produce quality.     

真空油炸紫薯片预处理工艺的优化

研究了真空油炸紫薯片的预处理工艺.应用单因素试验及正交试验设计方法,对切片厚度、漂烫条件、冷冻时间等真空油炸紫薯片质量的预处理因素进行了系统研究,确定了真空油炸紫薯片的最佳预处理工艺:切片厚度3.0 mm;漂烫温度95℃,漂烫时间3.5 min;在-20℃条件下,冷冻18 h;在-0.094～-0.098 MPa真空度条件下,90℃真空油炸15 min.真空油炸紫薯片最大程度地保存了紫薯的营养价值,花青素含量为1.54 mg/g,脂肪质量分数为17.40％,破碎力为468.9 N.产品带有清晰的纹理,口感酥脆,无油腻感.     

微波烫漂荷苞片后红色素提取工艺条件的研究

以蘘荷穗状花序苞片为原料提取红色素,比较了微波烫漂辅助法与其它不同方法及不同溶剂对红色素提取得率的影响,利用单因素实验和正交L16(44)实验研究了微波烫漂后蘘荷苞片红色素提取的工艺条件,结果表明经微波烫漂处理后,用酸性乙醇提取蘘荷苞片红色素效果较好;最佳工艺条件为:体积分数60%的酸性乙醇为提取剂,料液比1∶60(g/mL),提取温度55℃,时间40min,此条件下红色素的得率为345.8mg/100g。     

鲜海带漂烫过程中碘的溶出规律

通过跟踪测定漂烫水、漂洗水、剩余海带中的碘含量,研究了鲜海带漂烫-漂洗过程中碘的溶出规律。漂烫水、漂洗水中的碘质量浓度随海带的加入量增加均先增大后趋于稳定,且结合漂烫-漂洗过程对于碘的累积提取率曲线和拟合方程,选择在鲜海带加入量为3 kg/L时更换漂烫、漂洗水,可将海带中碘资源的利用率提升至46%。通过对比漂烫过程与漂烫-漂洗过程对于海带中碘的提取率,可知在原有漂烫工艺基础上增加漂洗过程,在有效提取阶段可将海带碘的提取率提升15%以上。     

双孢白蘑菇干燥前微波与高温瞬时蒸汽联合漂烫预处理对酶活和品质影响的研究

试验研究了双孢白蘑菇干燥前微波与高温瞬时蒸汽对多酚氧化酶(PPO)活性以及Vc的影响。通过微波强度(w/g)、微波处理时间(t1)、蒸汽强度(Pa/g)、蒸汽处理时间(t2)的单因素试验,设计正交试验,对PPO、Vc进行综合评价分析,得出最佳的试验条件:微波强度为5.656w/g、微波处理时间(t1)为120s、蒸汽强度为2.69Pa/g、蒸汽处理时间(t2)为80s,综合评分值最高。并对微波与高温蒸汽联合漂烫最优结果与热水漂烫处理、纯微波、纯高温蒸汽漂烫进行了比较,体现了微波与高温蒸汽联合漂烫的优势。