氯化钙对超高压处理的鲜切马铃薯硬度改善效果的研究

超高压（Ultra-high pressure,HPP）会造成鲜切马铃薯硬度的下降,为探究氯化钙对HPP处理的鲜切马铃薯硬度的改善效果,以鲜切马铃薯为原料,在不同氯化钙处理浓度、时间和浸泡方式下对HPP处理的鲜切马铃薯硬度的变化进行研究。结果表明：氯化钙真空浸渍硬度改善效果优于普通浸泡;在此基础上,采用响应面试验对氯化钙的改善效果进行优化分析得出不同浓度氯化钙及不同真空浸渍时间与不同超高压压力、压力作用时间作用于鲜切马铃薯是交互影响的,且氯化钙溶液浓度对鲜切马铃薯的质地影响最大。在HPP压力为300 MPa,作用时间10 min结合1.0%CaCl2,真空浸渍10 min 的处理条件下,鲜切马铃薯硬度值最大,为3284.83g,与未处理的鲜切马铃薯硬度相当,钙离子含量最高,为3157.82 ug/g,显著高于未处理组钙离子含量。     

基于X-射线衍射及扫描电子显微镜的马铃薯淀粉掺伪鉴别

目的建立一种快速、准确鉴别市售马铃薯淀粉掺伪的方法。方法将红薯、玉米及小麦淀粉按不同比例加入纯马铃薯淀粉中,通过X-射线衍射(X-ray diffraction,XRD)对样品进行结晶结构分析,并结合扫描电子显微镜(scanning electron microscope,SEM)进行微观形貌观察。结果利用结晶类型差异,XRD可初步判别马铃薯淀粉样品是否掺入上述3种淀粉,进一步采用SEM可观察到含量1%的掺伪淀粉并对其种类进行区分。在市售12批次马铃薯淀粉中的7批次中发现存在掺伪现象,其中2批次利用扫描电镜未观察到马铃薯淀粉(小于1%)。结论市售马铃薯淀粉掺伪现象严重,利用X-射线衍射及扫描电子显微镜可快速、准确地鉴别马铃薯淀粉掺伪情况。     

马铃薯雪花全粉真空冷冻干燥制备工艺及其性质

采用真空冷冻干燥技术制备马铃薯雪花全粉,对真空冷冻干燥马铃薯雪花全粉进行扫描电镜、X射线衍射、热特性及复水性分析。结果表明,真空冷冻干燥马铃薯雪花全粉的最佳参数为:升华干燥真空度100 Pa、升华干燥温度76℃、解析干燥真空度70 Pa、解析干燥温度45℃、装料量7.5 kg/m²,冻干速率11.362 3%/h。扫描电镜观察真空冷冻干燥马铃薯雪花全粉其颗粒均一; X射线衍射表明真空冷冻干燥工艺可减少结构破坏;热特性表明真空冷冻干燥马铃薯雪花全粉热稳定性较好,糊化度低,复水性较好,为即食马铃薯泥等产品开发提供依据。     

X-射线和红外光谱研究马铃薯蛋糕老化特性

以X-射线衍射(XRD)和傅里叶变换红外光谱(FT-IR)研究马铃薯蛋糕在贮藏期间(1、24、72、120、168 h)的老化特性,并利用质构仪和色差研究了老化对蛋糕品质(质构、色差)的影响。结果表明,蛋糕贮藏1 h后,在X-射线2θ12.5°和20°附近出现衍射峰,分别对应于禾谷类淀粉的无定形峰和由直链淀粉与脂肪酸形成的螺旋形复合物——V-型结晶,当贮藏时间达到120 h时,在2θ17°附近出现由支链淀粉回生产生的B-型结晶。FT-IR在波数925、995、1 025、1 047、1 079、1 155和1 243 cm-1附近出现吸收峰,1 025和1 047 cm-1附近的吸收峰分别对应淀粉的非结晶区特征和结晶区特征,(1 047/1 025) cm-1峰强度比值能够反映淀粉分子的有序程度,其比值越大,有序度越高。马铃薯蛋糕在贮藏期间的X-射线衍射峰和红外吸收峰强度以及(1 047/1 025) cm-1比值均小于普通蛋糕,表明其老化速度慢于普通蛋糕。老化会导致蛋糕硬度、咀嚼性、胶着性、a*和b*值增加,黏聚性和L*值降低,从而使蛋糕失去光泽、口感变粗糙、风味发生劣变。     

Firmness Retention in Pickled Peppers as Affected by Calcium Chloride, Acetic Acid, and Pasteurization

Critical factors influencing firmness retention in pickled peppers were studied. The addition of CaCl, (0.2%, w/v, optimum) to whole, pickled‘Red Cherry’peppers increased firmness retention as determined by a puncture test using an Instron Universal Testing Machine. Pasteurization reduced firmness in the absence, but not in the presence, of added CaCl₂. CaCl₂ significantly (P ≤0.01) reduced softening during storage of‘Red Cherry’peppers at higher temperatures (36.7, 46.7°C), and resulted in a slight increase in firmness at 26.7°C. CaCI₂ did not significantly (P≥ 0.05) improve firmness retention in‘Jala-peno’peppers, but resulted in greater uniformity of firmness. CaCI, also improved firmness retention in pickled cucumbers. Firmness of unpasteurized peppers and cucumbers was not influenced significantly (P ≥0.05) by acetic acid concentrations of 2, 3 or 4%.     

Firmness and Cell Wall Characteristics of Pasteurized Jalapeño Pepper Rings Affected by Calcium Chloride and Acetic Acid

Pepper rings packed in brine containing CaCl₂ were firmer, had higher bound calcium, chelator soluble pectin and pectin DE, and less water-soluble pectin (WSP) than peppers packed in brine containing no CaCl₂. Pepper rings packed in low acid brines (1% and 1.2% acetic acid) were firmer and had less WSP than those packed in high acid brine. Those samples (4% acetic acid) resulted in softening and pectin solubilization, but CaCl₂ resulted in less softening. Monosaccharide composition of cell walls was not affected by CaCl₂ or acetic acid. Firmness retention in CaCl₂ treated samples was probably due to greater association between calcium ions and pectic substances, which resisted acid hydrolysis.     

真空斩拌和钙离子浓度对白鲢鱼糜胶凝特性的影响

本文研究了真空和钙离子对白鲢鱼糜胶凝特性的影响,以期为高品质鱼糜制品的加工提供理论依据。结果如下:随着钙离子浓度增加,常压斩拌的鱼糜凝胶的破断力呈现出先增大后减小、然后增大再减小的趋势,两个峰值对应的浓度分别为20 mmol/kg和40 mmol/kg;蛋白的交联程度逐渐从18.08%增加到30.98%,在钙离子浓度高于30 mmol/kg后逐渐降低并达到最小值14.54%;微观结构从无特征性结构转变为连续的网络结构、再转变为分散的聚集体。真空条件下,鱼糜凝胶特性值(破断力、和蛋白交联度)和微观结构随钙离子浓度变化的趋势与常压条件下相同,但是峰值或转变点所对应的钙离子浓度均低10 mmol/kg。真空和常压条件下,持水性随着钙离子浓度增加均逐渐从80.74%和82.27%分别降低到62.09%和67.23%,白度值逐渐从79.11和79.10分别增加到83.80和83.15。结果表明,真空具有降低钙离子影响鱼糜胶凝特性"效应浓度"的作用。     

异抗坏血酸与氯化钙联合处理对鲜切芒果的保鲜效果

为研究异抗坏血酸与氯化钙联合处理对鲜切芒果保鲜效果的影响,鲜切芒果在1 g/100 mL异抗坏血酸和0.5 g/100 mL氯化钙的混合溶液中浸渍处理5 min后,4℃相对湿度80%条件下贮藏15 d,每天取样测定呼吸速率,每3 d测定细胞膜相对渗透率、硬度、可滴定酸、类胡萝卜素、抗坏血酸(AsA)、总酚、褐变指数、超氧阴离子(O₂^-·)产生速率、抗氧化酶及多酚氧化酶(PPO)活性等指标。结果表明:与对照相比,异抗坏血酸+氯化钙联合处理使鲜切芒果的呼吸峰值降低了41.20%,并延缓相对渗透率升高和硬度下降;保持较高的类胡萝卜素、AsA含量,维持总酚含量相对稳定,在贮藏前期保持了较高的可滴定酸含量,减少褐变发生;降低了O₂^-·产生速率,明显抑制PPO的活性,提高超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)的活性,并且在0~9 d时延缓过氧化物酶(POD)的下降,但在贮藏后期降低了POD的活性。以上结果表明异抗坏血酸+氯化钙联合处理可以保持鲜切芒果较好的贮藏品质,延缓膜透性增加并提高活性氧(ROS)的清除能力,从而延缓衰老,抑制褐变。     

Effect of Sodium Chloride, Acetic Acid, and Enzymes on Carotene Extraction in Carrots (Daucus carota L.)

ABSTRACT: Carrot root cores were cut off longitudinally and treated with NaCl (0.6 and 1.2 M ) and/or acetic acid (1.33%, 2.67%, and 4%) solutions. The extractability of the carotenes was estimated. Similarly, carrot cores were also treated with some degrading enzymes (carbohydrases, lipases, and proteases) alone or in combination to study the effect of the tissue rupture or the hydrolysis of possible complexes or interactions between carotenes and other components on the carotene extractability. The results showed that acetic acid increased the extractability of α- and β carotenes up to 99.8% and 94.6%, respectively, at a 4% acid concentration compared with the samples without any treatment. This increase was directly proportional to the acid concentration. An increase in extractability was also observed for NaCl, although the increases were not as high as in the previous case with values of 49% and 41.4% for α- and β-carotenes respectively at a 0.6 M concentration. The study of microstructural changes and extractability revealed that the enzymatic treatments could have broken some carotene complexes and interactions and altered the carbohydrate matrix structure, increasing to a certain extent the extractability of carotenes. It can be concluded then that pickling with 4% acetic acid is a good method to increase the extractability of α- and β-carotenes.     

Extension of Shelf Life by Treatment with Allyl Isothiocyanate in Combination with Acetic Acid on Cooked Rice

ABSTRACT: In order to extend the shelf life of cooked rice, allyl isothiocyanate (AIT) and acetic acid were applied, and both microbiological evaluations and sensory evaluations were performed during storage at various temperatures. The residual AIT concentration in the headspace of a cooked rice pack was also quantified. Total aerobic populations at various storage temperatures were lower where acetic acid alone or in combination with AIT were used. A sensory evaluation showed that the acceptability of cooked rice was influenced by the type of treatment. The antimicrobial effect of acetic acid in combination with AIT was excellent, so it seemed to have potential as an agent to extend the shelf life of cooked rice.     

山梨酸钠固相反应生产过程中的微观特征

采用山梨酸和碳酸钠固相反应生产山梨酸钠过程中,会出现反应体系温度突然升高,反应物粘接,反应不易进行彻底,碱的加入量超过化学反应比例等问题,从而影响反应的进行和产品质量.为解决这些问题,利用X-射线衍射、扫描电镜、差热及热重分析方法,对其固相反应过程的微观变化特征进行研究,结果表明:山梨酸与碳酸钠固相反应产生的热、水及研...     

液体钙脱硝在全卤制烧碱中的应用探讨

文章提出将液体钙脱硝与膜法脱硝相结合,使盐水中SO24-含量满足离子膜制碱的工艺要求,最终实现全卤制烧碱.并通过对比分析,看出工艺在烧碱生产中具有明显的优势.     

基于多元统计学分析红曲米醋醋酸发酵阶段挥发性风味特征组分

为探究红曲米醋酿造过程中挥发性风味及特性组分变化规律,以红曲米醋醋酸发酵阶段为研究对象,采用电子鼻、气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）联用和气相色谱-嗅闻（gas chromatography-olfactometry,GC-O）联用技术对挥发性风味物质进行分析,并结合聚类分析、主成分分析和偏最小二乘判别法的多元统计方法进行不同发酵阶段的风味物质差异性分析,最终筛选出特征性组分。电子鼻分析可用于区分不同发酵时期的红曲米醋。通过GC-MS和GC-O识别出发酵过程中共有54 种挥发性风味化合物。经多元统计学方法筛选得到挥发性风味特征组分,醋酸发酵早期为正辛醇、异丁醇和戊酸乙酯;中期为苯甲酸、棕榈酸乙酯、正己醇、2,4-二叔丁基苯酚和乳酸乙酯;中后期为乙酸丙酯、乳酸乙酯和乙酸异丁酯;末期为L(＋)-2,3-丁二醇和庚酸乙酯。本研究结果为红曲米醋香气的调控和风味改善提供重要理论依据。     

The Effect of Brine Ingredients on Carrot Texture during Thermal Processing in Relation to Pectin Depolymerization due to the β-Elimination Reaction

ABSTRACT:  Thermal texture degradation of carrots was studied at a temperature of 100 °C in aqueous solutions containing sodium chloride, citric acid, ascorbic acid, and ethylenediaminetetraacetic acid (EDTA) at different concentrations. To enhance the texture of the final product, the carrot samples were pretreated at 65 °C for 30 min in an aqueous calcium chloride solution (5 g/L). For all case studies considered, the pH of the solutions was adjusted to pH = 6.0. In parallel, both the changes in degree of esterification (DE) and the progress of the β-elimination reaction of carrot pectin under the same conditions were investigated. The kinetic parameters for texture degradation (rate constant k_t and final texture value [TP_∞/TP₀]) were estimated using a fractional conversion model. The results indicate that both the rate constant for texture degradation ( k_t ) and the rate constant for the β-elimination reaction ( k_b ) increased with increasing additive concentration, while the final texture values (TP_∞/TP₀) and DE decreased with increasing additive concentration in all systems studied. A high correlation was observed between the relative rate constant for texture degradation and the relative rate constant for the β-elimination reaction on the one hand, and the relative final texture value and the relative rate constant for the β-elimination reaction on the other hand, suggesting that the influence of the solutes on texture degradation can be explained by their influence on the β-elimination reaction.