Enzymatic Firming of Processed Red Pepper by Means of Exogenous Pectinesterase

Abstract

The objective of this investigation was to demonstrate that the firmness of a commercial vegetable product, diced and frozen red pepper (Capsicum annum var. Sendt), could be improved by the use of exogenous pectinesterase in an industrially relevant process. The diced pepper pieces 10?×?10?×?7?mm³ were infused under vacuum with a commercially available pectinesterase. The range of optimal process conditions was: 15–20°C, 45?min infusion time, a 10–25?mM CaCl₂ infusion brine, a w/w ratio of pepper fruit to infusion brine of 1.5:1, and an enzyme dosage of 30–60 pectinesterase units (PEU) per kg pepper fruit. The firmness as measured by back extrusion was improved by a factor of two to three. The effect of firming was robust and conserved after freezing and heating in a simulated household cooking process. The firming process seems easily adaptable to industrial conditions and may be applicable to other vegetable and fruit products.     

Firming of starch gels and amylopectin retrogradation as related to dextrin production by α-amylase

 The effect of dextrins produced by α-amylase on the firming and amylopectin retrogradation of wheat starch gels was studied. Different gel samples were prepared and included several ingredients, for example, α-amylase, vital gluten and glucoamylase. Amylopectin retrogradation, gel firming and the dextrin profile were analysed throughout a 5-day storage period. Both processes, i.e. firming and starch retrogradation, increased with time, and were not affected by the incorporation of gluten into the mixture. The well-known effect of α-amylase to retard bread crumb firming was also found to be relevant to starch gels. From the results obtained in this work, it seems that this anti-firming effect is not due to modifications of the starch but to dextrins produced by starch hydrolysis, since the effect did not occur when dextrins were removed by glucoamylase. Received: 30 December 1996     

Firming of fruit tissues by vacuum-infusion of pectin methylesterase: Visualisation of enzyme action

Apple pieces were vacuum-impregnated with either a pectin methylesterase (PME) and calcium solution or with water prior to pasteurization. Pasteurized apple pieces impregnated with PME and calcium showed a significantly higher firmness. Moreover, solid state ¹³C NMR spectroscopy of apple cell wall residues revealed an increase of their molecular rigidity. Exogenous PME addition involved a decrease from 82% to 45% of apple pectin degree of methyl-esterification. Microscopic observations of apple slices immunolabelled with antibodies specific for pectins showed that (i) demethyl-esterification was more intense in the cell wall region lining intercellular spaces (demonstrating a key role for these intercellular channels in the enzyme penetration in the tissue during vacuum-infusion) and that (ii) the number of calcium-dimerized deesterified homogalacturonan chains increased. The results corroborate the hypothesis that vacuum-impregnated PME action liberates free carboxyl groups along pectin chains that could interact with calcium, increasing the rigidity of pectins and finally the mechanical rigidity of apple tissue.     

Reduction in the pH of vegetables by vacuum impregnation: A study on pepper

A method to decrease pH value in pepper slices employing vacuum was studied. The effects of relaxation time (10, 15 and 30 min), vacuum level (200 and 400 mbar) and vacuum application period (2 and 5 min) were evaluated. Results showed that vacuum impregnation (VI) with lactic acid solution increased the acidification degree to a greater extent than processing carried out at atmospheric pressure. In particular, samples treated at 400 and 200 mbar and submitted to a relaxation period of 30 min, showed a reduction in pH ratio (RpH) from 0.929 to 0.894. Otherwise, samples submitted to conventional dipping at atmospheric pressure showed a RpH of 0.968. Vacuum level was found to be the most important variable influencing the variations in total mass and pH. Vacuum impregnation led to an increase in diffusion rate of hydrogen ions into the vegetable tissue due to the increase in contact area between acid solution and cells. Moreover, a direct correlation between pH reduction on the one hand, and vacuum application period and relaxation time on the other, was observed. Results proved that vacuum impregnation process is a useful technique to improve acidification treatments of vegetables.     

酶法制备甲壳低聚糖

壳聚糖经水解后形成的低分子量壳聚糖具有许多独特的生理活性，近年来已成为甲壳质研究领域中热点。就酶法制备低分子量壳聚糖的方法进行了综述性报道。     

Utilization of partially ripe mangoes for freezing preservation by impregnation of mango juice and sugars

Frozen mango is texturally damaged due to formation of ice crystals during freezing preservation. The objective of this investigation was to use partially ripe mango as an alternative for ripe mango. Based on its stronger structure, partially ripe mango could better withstand texture damage by ice crystals. Its flavor and color could be enhanced by impregnation of mango juice and sugars (natural flavor) into the mango matrix. This investigation found that calcium carbide incubation for two days helped prepare the mango at a partially ripe state. Vacuum infusion was more effective than natural mass diffusion in incorporation of mango juice-sugar mixture (shorter soaking time (˜10 min at 74.66 kPa) and better mango quality (texture, solid content and color sensory scores ˜7-8 in a traditional 9-point hedonic scale). After freezing (air-blast, jet-impingement and cryogenic freezing) and thawing, the juice/sugar-infused mangoes were high in sensory scores (7-8) and low in drip loss (9-12 g/100g) values. They better tolerated freezing damage than did ripe mango. This proposed method can help reduce the post-harvest losses arising from the faster spoilage of more ripe mangoes. It enhances natural flavor and taste of the partially forced ripening mangoes which normally impart only color.     

Determination of the carotenoid content in selected vegetables and fruit by HPLC and photodiode array detection

 Epidemiological studies have shown inverse correlations between the consumption of vegetables and fruit rich in carotenoids and the incidence of cancer and cardiovascular diseases. A total of 22 species of vegetables (including potatoes) and 28 of fruit (including rhubarb) were analysed for their contents of carotenoids by reversed-phase high-performance liquid chromatography (RP-HPLC) and photodiode array detection. A total of 27 carotenoids (among them β-carotene, lutein and violaxanthin also as cis isomers) were identified and quantified. Lutein, β-carotene (trans and cis forms) and violaxanthin were the predominant carotenoids in all green vegetables. Yellow and yellow-red vegetables and fruit contained β-carotene, α-carotene, β-cryptoxanthin and α-cryptoxanthin. Antheraxanthin and neoxanthin were found in nearly all produce. Lycopene was the predominant carotene in tomatoes, papayas and grapefruit. Vegetables with more than 10 mg of total carotenoids per 100-g edible portion were kale (34.8), red paprika (30.4), parsley (25.7), spinach (17.3), lamb’s lettuce (16.0), carrots (15.9) and tomatoes (12.7). In the case of fruit, grapefruit (3.5), papayas (3.4) and nectarines (2.4) were pre-eminent with more than 2 mg of total carotenoids (except for phytoene, phytofluene and ζ-carotene) per 100 g. Received: 27 March 1996     

QuEChERS前处理结合气相色谱电子捕获检测器检测果蔬中30种农药残留

目的 应用QuEchERS前处理法处理样品,建立了气相色谱-电子捕获检测器检测多种水果蔬菜中30种常见农药残留的分析方法。方法 用乙腈作为溶剂,分别采用无缓冲盐体系、醋酸缓冲盐体系和柠檬酸盐缓冲体系提取对蔬果中30种农药进行提取,用PSA进行净化后上机处理。结果 采用不加缓冲盐体系提取,经PSA净化的方法适用于本文所选30种农药的检测,将该方法用于黄瓜、西红柿、生菜、苔菜、包菜、胡萝卜、梨、草梅,苹果等蔬果中30种农残的检测,结果表明30种农药残留的回收率在75%-122%之间,相对标准偏差在1%-12%之间;结论 该方法准确、简单、快速、灵敏度高,可以满足日常农残快速筛选的检测要求。     

利用热风喷雾干燥方法生产纯天然柑橘(橙)果粉

将柑橘（橙）全果皮肉分离，果皮经热烫、水漂及果胶酶适度处理后，与去籽的果肉以1：1.4～1：1．6的比例混合，利用热风喷雾干燥方法可获得干燥、疏松的纯天然柑橘（橙）果粉。     

红曲米粉安全性控制技术

研究了国内市场上销售的不同产地红曲米粉的辐射灭菌效果,对辐照红曲米粉的感官指标、理化指标和微生物指标进行了检测,结果表明:6kGy以上的γ射线可以有效杀灭红曲米粉中的微生物,辐照红曲米粉的感官指标、主要营养成分与未辐照无明显差异,但会导致色价的降低。商业化应用效果表明,采用静态堆码辐照,工艺剂量上限和下限分别为6kGy和8kGy,总体平均吸收剂量控制在7kGy,可确保红曲米粉的卫生质量、色价损失率在2%以下。     

响应面法优化红干椒中辣椒红色素提取工艺

采用超声波法快速提取红干椒中的辣椒红色素,在确定样本容量的基础上,考察了超声温度、超声时间和超声功率对测定结果的影响,采用响应面分析法确定了最佳提取条件.结果表明:采用超声波法提取辣椒红色素时,辣椒取样量为15个,辣椒粉末取样量为1.000 g,超声温度48℃,提取时间23 min,提取功率40 W.采用此方法处理样品时,缩短了提取时间,简化了测定步骤,所得数据重复性好,易于同时测定大批量样品中的辣椒红色素含量.     

Analyses of Glycolipids in Clove, Red Pepper, and Nutmeg by High-Performance Liquid Chromatography

ABSTRACT: To determine the existence of glycolipids (neutral glycosphingolipid and glycoglycerolipid) in clove, red pepper, and nutmeg, we performed silica gel chromatography and high-performance liquid chromatography (HPLC) using an Aquasil-SS column and a C₈-reversed-phase silica gel column. HPLC (Aquasil-SS column) with a UV absorption detector was used to analyze neutral glycosphingolipid. These chromatograms showed two typical peaks in clove lipids. UV-HPLC (C₈-reversed phase silica gel column) was also used to analyze glycoglycerolipid. The chromatograms indicated a small peak in clove lipids. Moreover, we observed the same two peaks in the glycolipid fraction of clove lipid when we used HPLC (Aquasil-SS column) with a differential refractometer detector. These results suggest that clove may contain new and plural neutral glycosphingolipids.     

Enzymatic properties of transglutaminase produced by a new strain of Bacillus circulans BL32 and its action over food proteins

The aim of this study was to physicochemically characterize transglutaminase (TGase) from Bacillus circulans BL32, a strain recently isolated from the Amazon basin region, for its application in food systems. The effects of pH and temperature on the enzyme activity were determined by Central Composite Rotatable Design (CCRD), with maximal TGase activities obtained for pH between 5.7 and 8.7 and temperatures of 25-45 °C. This microbial TGase showed to be remarkably stable: over 90% of its activity was retained after 120 min of incubation at 50 °C. The Ca²⁺ and Mg²⁺ cations enhanced enzyme activity and its thermal stability when in concentrations of up to 2 and 1 mol L⁻¹, respectively. Casein, isolated soy protein, and hydrolysed animal protein were treated with this TGase. The decrease in the amount of free amino groups, especially for casein, showed the cross-linking of protein catalysed by this enzyme, while the emulsifying properties of these proteins were improved with treatment. These results suggest that this microbial TGase has a good potential to be used in food and other industrial applications.     

酶解对植物乳杆菌发酵红枣汁品质的影响

为了明晰酶解处理对发酵红枣汁品质的影响,采用果胶酶和半纤维素酶酶解红枣浆,研究经植物乳杆菌发酵后及4℃贮藏期间乳酸菌活菌数、主要营养品质和色泽的变化。结果表明,与对照相比,酶解处理可显著提高红枣汁的可溶性固形物含量和可滴定酸含量。酶解处理有利于保持红枣汁贮藏期间的抗坏血酸含量、多酚含量和蛋白质含量,在贮藏28d时,其含量分别高出对照0.7、0.28mg/100mL和0.58mg/100mL,多糖含量也有小幅增加,色泽有明显改善。此外,酶解处理提高了红枣汁中的乳酸菌活菌数,在贮藏28d时,酶解处理组的乳酸菌活菌数显著高出对照组0.17(lg(CFU/mL))。表明红枣汁发酵前采取酶解处理可以改善红枣汁的后续发酵品质。     

响应面优化水酶法提取红树莓籽油工艺

以红树莓籽为原料,在单因素试验基础上,以红树莓籽油提取得率为指标,通过响应面分析建立水酶法提取红树莓籽油工艺模型。结果表明,红树莓籽油最佳提取条件为:料液比1∶5.5(g/mL)、酶添加量1.9%、酶解时间3.9 h、p H 7.3,此条件下进行3次平行验证试验,所得红树莓籽油提取得率为6.25%,与预测值基本相符。     

高效液相色谱-荧光检测法测定红肉及其加工肉中唾液酸含量

采用高效液相色谱-荧光检测法对红肉及其加工肉中两种唾液酸N-乙酰神经氨酸(N-acetylneuraminic acid,Neu5Ac)和N-羟乙酰神经氨酸(N-glycolylneuraminic acid,Neu5Gc)进行定性和定量分析.利用单因素试验对衍生化与样品酸解条件进行优化,并借助超声缩短酸解时间.结果表...     

响应面优化超声辅助酶法提取辣椒红色素研究

以铁皮辣椒为原料,在单因素实验的基础上,选择超声功率、乙醇浓度、超声时间、酶用量进行四因素三水平的Box-Benhnken买验,利用Design-Expert 8.0软件进行响应面分析.响应面法优化结果表明,在超声功率434W、乙醇浓度75.5％、超声时间76.3 min、酶用量4 mg的条件下,辣椒红色素的提取效果最...     

响应面法优化水果酵素、茶多酚和维生素C对亚硝酸盐的消除作用

目的探讨水果酵素、茶多酚和维生素C对亚硝酸盐的消除效果。方法通过单因素试验,研究水果酵素、茶多酚和维生素C对亚硝酸盐的消除率的影响。在单因素实验基础上,用响应面分析法对水果酵素、茶多酚和维生素C的组合进行优化。结果通过响应面法优化得到消除亚硝酸盐的最佳工艺条件:茶多酚(0.1%)用量1.0 m L、维生素C(0.1%)用量1.0 m L,水果酵素(1%)用量4.0 m L,消除率达到99.48%。结论水果酵素作为一种健康发酵品,在模拟胃酸条件下,协同茶多酚和维生素C对亚硝酸盐具有很好的消除效果。