Effect of dielectric microwave heating on the color and antiradical capacity of betanin

The decomposition of betanin under dielectric heating (microwave irradiation, power: 25–200 W (3–24 kJ g⁻¹)) follows first-order kinetics with a rate constant similar to that obtained during conventional conduction heating (half-life < 2 min at 100 °C). Color coordinate analysis indicates that betanin is bleached upon thermal treatment, whereas beetroot juice and spray-dried beetroot powder tend to form colored decomposition products. The antiradical capacity of betanin decreases upon heating, but is still much higher than that of standard antioxidants such as ascorbic acid and trolox. Betalamic acid, a high capacity antiradical, was detected by mass spectrometry and second-derivative absorption spectroscopy in betanin samples submitted to thermal treatment.     

Stability of betacyanin from red pitahaya (Hylocereus polyrhizus) and its potential application as a natural colourant in milk

The effects of temperature (30, 50, 85 and 100 °C) treatment and 10 weeks of refrigerated storage (4 °C) on the betacyanin content and colour stability of betacyanins from red pitahaya (Hylocereus polyrhizus) were investigated and compared to red beet (Beta vulgaris; E‐162) which was used as a control. Temperature treatment at 50 and 85 °C caused a greater reduction in betacyanin content (BC) in E‐162 compared to red pitahaya by inducing changes in betacyanin profile. The 10 weeks of refrigerated storage at 4 °C induced colour changes in betacyanins from red pitahaya and E‐162. In milk, betacyanins from red pitahaya presented a lower loss of BC and total colour changes (ΔE*) compared to E‐162. The microbial onset in milk containing betacyanins from red pitahaya and E‐162 was delayed up to day 5 of refrigerated storage at 4 °C compared to day 3 in plain milk. Milk containing betacyanins from red pitahaya showed better colour acceptability (3.89 ± 1.89) compared to E‐162 (6.10 ± 1.71). Hence, betacyanins from red pitahaya may be a potential natural functional colourant to simulate strawberry colour in milk.     

Microwave-assisted extraction of betalains from red beet (Beta vulgaris)

The use of microwave assisted extraction (MAE) was investigated in this work for the extraction of betalains from diced red beets. Several treatments with different combinations of time, power and duty cycle applied to the samples were studied. The combination of 400 W and 100% duty cycle for 90–120 s resulted in the highest amount of recovered betanines; whereas at 140–150 s the highest amount of betaxanthins was obtained. The addition of ascorbic acid (0.040 mol/L) to the extracting solvent and the development of a two-step MAE process with a cooling period in-between and after processing steps led to an enhancement in the amount of pigments obtained. The effect of extraction time at each extraction step on betalains yield was determined by applying a factorial design and surface plots were constructed. The duration of the second step significantly affected the yield of betanines and betaxanthins obtained (p < 0.05). A prediction model was proposed and validated to meet the optimal extraction times. Betalain yields obtained by MAE were twice as high as those obtained during conventional extraction and conventional extraction at 80 °C.     

Betalainic and nutritional profiles of pigment-enriched red beet root (Beta vulgaris L.) dried extracts

Red beet root (Beta vulgaris L.) colourants (betalains) are available either as concentrates produced by evaporating beet juice under vacuum, or as powders made by spray-drying a concentrate. The degradation of the pigments is dependent upon temperature, duration of heat treatment, pH and water activity of a product. Recently, a new proprietary method of large-scale chromatographic purification of red beet root extract has been discovered and developed that allows the production of more concentrated betalain formulations. In order to trace the betalainic compositions of the new products in comparison to the currently in-use spray-, air- and freeze-dried concentrates, a chromatographic study on betalains and their degradation derivatives analysed by LC-DAD-ESI-MS/MS was performed. Additionally, nutritional characterisation of the extracts was accomplished.     

甜菜红色素对蚕丝织物染色工艺研究

对甜菜红色素染色蚕丝织物的染色性能进行了研究.研究结果表明,直接染色最佳工艺为:pH值为3,温度30℃,时间40 min;壳聚糖处理后染色和媒染染色都能显著提高上染百分率,媒染染色后摩擦牢度和水洗牢度均有所提高.     

Production of a red–purple food colorant from Opuntia stricta fruits by spray drying and its application in food model systems

Opuntia stricta fruit juice is a potential source of betacyanin pigments which can be used as a natural red-purple food colorant. In this work a powder food colorant was obtained by co-current spray drying of O. stricta fruit juices with a bench-scale two fluid nozzle spray dryer. Glucose syrup (DE 29) was used as drying aid. Optimum conditions for spray drying were as follow: juice content (20% v/v; 1.2 °Brix), glucose syrup content (10% w/v), liquid feed rate (0.72 l/h), spray air flow-rate (0.47 m³/h), drying air flow-rate (36 m³/h), and inlet drying air temperature 160 °C. Color was retained during the drying process (>98%) and drying yield was high (58%). The powder colorant showed high color strength (4.0), being this color strength stable when stored at room temperature for one month. This colorant was successfully applied in two food model systems: a yogurt and a soft-drink. Food presented a vivid red-purple tonality very attractive for consumers that was maintained after one month under refrigeration (4 °C) (ΔE < 5).     

The isolation and properties of a concentrated red‐purple betacyanin food colourant from Opuntia stricta fruits

A red‐purple food colourant from Opuntia stricta fruits was obtained and studied. Four steps were involved in its isolation: washing, extraction, centrifugation and concentration. Ethanol:water 60:40 (v/v) was selected as the optimum extraction solvent to reduce the viscosity caused by the presence of mucilage and pectins. The resulting 40‐fold concentrated extract had a high colour strength (3.9, OD 535 nm, 1% v/v sol), a high betanin concentration (4.7 g L⁻¹) and low viscosity (59.0 cP). It also showed high stability (t_1/2 = 236.6 d, 4 °C) mainly due to its low pH (3.4) and low water content (571 g kg⁻¹). These characteristics were in the same range as shown by three commercially available liquid concentrated colourants studied (red beet, red carrot and red grape skin). The colour parameters of this concentrated extract of Opuntia stricta were compared with those of commercial red colourants (red beet, red carrot, red grape skin, cochineal, elderberry, hibiscus and red cabbage). CIELAB values of Opuntia stricta (1.5 mL L⁻¹) were L* = 69.8, a* = 59.7 and b* = −23.5. Opuntia stricta presented a vivid red‐purple colour which was distinguishable from the colours shown by the other natural red food colourants. Copyright © 2005 Society of Chemical Industry     

延长真空包装红肠货架期的研究

本试验为对真空包装的红肠进行处理,以延长其货架期.试验分两批,第一批为筛选试验,结果表明加热处理方法和微波处理方法效果要显著好于化学防腐剂处理方法,第二批为不同热处理方法和时间的比较,结果表明真空包装后用沸水煮制15min组效果最好,常温贮存14天细菌总数远远低于国标,而对照组贮存7天则细菌总数达2.7×10~6个/g,已超过了国家标准.     

Pulsed electric field assisted aqueous extraction of colorants from red beet

This work discusses the temperature effects (T = 30-80 °C) on degradation of colorants and kinetics of their extraction from the red beet both untreated and treated by pulsed electric field (PEF). PEF treatment was done using the trains of monopolar rectangular 100 μs pulses with electric field strength E = 375-1500 V cm⁻¹, and total treatment time t_PEF = 0-0.2 s. The degradation of colorants and their extraction were characterized by means of absorbance and electrical conductivity measurements. PEF treatment was found effective for acceleration of the extraction of betalains and reducing the time of extraction. Electroporation was shown to be responsible for intensification of the release of colorants through aqueous extraction.     

The influence of Lactobacillus bacteria type and kind of carrier on the properties of spray-dried microencapsules of fermented beetroot powders

The aim of this study was to evaluate the influence of bacteria type and carrier addition during microencapsulation process by spray-drying on the microorganism survival and physicochemical properties of fermented beetroot juice powder. Selected bacteria were as follows: L. fermentum, L. plantarum and L. brevis and its mixture in proportion 1:1:1. Fermented beetroot juice containing selected LAB was spray-dried at 160 °C. Maltodextrin and gum Arabic were used as drying carriers at 10% (w/w). All powders were stable (low water activity below <0.25, high dry matter content 95–98%). Bacteria type had the main influence on the chemical properties and amount of bacteria. The highest bacteria content was observed in powders with L. brevis as a starter, and the same was observed for polyphenols and betalain content. However, the method of drying fermented juices still needs to be refined due to the 50% reduction in the number of microorganisms during the drying process.     

Evaluation of different methods for the production of juice concentrates and fruit powders from cactus pear

The present work aimed both at improvement and extension of a previously developed process for the production of cactus pear juice. The total yield was increased by 10% through processing whole instead of peeled fruits and by further optimisation of pulp enzymation. As an alternative to HTST pasteurisation, cross-flow microfiltration was applied for non-thermal cactus pear juice preservation. Juice concentrates and fruit powders were produced by rotary evaporation and freeze drying at laboratory scale and compared to products obtained at pilot plant-scale applying a three-stage column evaporator and spray drying, respectively. To monitor process-related quality changes, the resulting products were characterised in terms of colour and selected quality parameters. For both juice concentrates and fruit powders, initial colour characteristics were retained. In addition to betanin isomerisation, C₁₁-epimerisation of proline-betaxanthin was demonstrated to be a valuable indicator of the respective heat treatment applied. Whereas no adverse reactions were observed during juice production, non-enzymatic browning and HMF formation were found after concentration at pilot plant-scale and freeze drying, respectively.

Industrial relevance

Although cactus pear meets all requirements for food colouring purposes, no attempt has been made so far to exploit this potential. The feasibility of processing cactus pear juice into concentrates and fruit powders was demonstrated in this study. In contrast to single-strength juice, concentrates and powders are easier to handle during transportation and storage and also open further fields of application that may promote cactus pear fruit processing at industrial scale in the future.     

保健食用油一紫苏油研究进展

紫苏油作为一种优良的保健食用油,对其组成成分、理化性质和生理作用等作了综述,并对其开发前景进行了展望.     

A comparative study of the anti-listerial activity of smear bacteria

Cell-free supernatants from Staphylococcus epidermidis, Staphylococcus warneri and Brevibacterium linens were found to possess anti-listerial activities. Anti-listerial activities were increased during exponential growth phase and reached a maximum during stationary growth phase. S. epidermidis (SE1) and S. warneri (SW1) were found to have particularly high activities against both Listeria monocytogenes and Listeria innocua as inhibition zones for 48 h cell-free supernatants of these strains were found on average to be approximately 10 times larger than those of B. linens (9174, M18 and BL1). Incubation of 48 h cell-free supernatants from S. epidermidis (SE1) and S. warneri (SW1) with proteolytic enzymes (trypsin and pronase E) resulted in a total loss of anti-listerial activity, which revealed its proteinaceous nature, and thus suggested that the observed anti-listerial activities were due to bacteriocin production. The bacteriocins were found to be relatively heat stable and had a molecular mass higher than 30 kDa.     

姜辣素的分离和纯化工艺研究

对姜辣素的分离和纯化工艺研究表明,以萃取压力、萃取温度、萃取时间为主要考察因素,作L9(34)正交实验,优化出提取姜精油最佳的工艺参数:SC-CO2萃取压力为30MPa;温度为50℃;时间为180min。经过有机溶剂对其萃取,使姜辣素进一步分离,采用大孔树脂为层析柱填充料对姜辣素进行纯化,得到纯度为56.4%的姜辣素。     

竹原纤维结构和力学性能研究

文章主要研究了竹原纤维的基本形态特征;同时对竹原纤维的力学性能特点作了详细分析.     

A comparative study on properties of dual-core yarns

Core-spun yarns containing Spandex have been widely used for the production of elastic textile materials. However, it has been encountered various problems not only during the usage but also during textile processes due to its high recovery property. In order to solve these problems, multicomponent core-spun yarns called as dual-core (DC) yarns, have been developed. DC yarns can be produced on the modified ring spinning machine in two different ways. In the first method, previously combined two core yarns are fed simultaneously, whereas in the second method, two core yarns are given separately into the centre of sheath fibre bundle. In present study, it was aimed to research the effect of these production methods on yarn features. Polyester and Spandex core components and cotton wrapping fibres were brought together in both two ways and the properties of multicomponent core-spun yarns were compared with cotton ring counterparts for three different yarn counts.     

黑莓天然维生素E纯化技术研究

目的建立一种硅胶柱层析纯化黑莓种籽油中天然VE的方法。方法采用单因素实验的方法,以维生素E的含量为考察指标,对洗脱剂种类、洗脱剂配比、硅胶用量、洗脱剂用量进行优化。结果黑莓天然VE的最优纯化工艺参数为:硅胶与维生素E粗提物的质量比3?1;乙醇?正己烷(8?1,V/V)为洗脱剂,洗脱剂用量为粗提物的15倍。在此条件下,纯化物中维生素E的含量可以达到(51.5±0.530)%。结论采用硅胶柱层析方法可以有效纯化黑莓天然维生素E。     

再生纤维热分散系统的性能比较

除去废纸中的胶粘物主要有辊式、盘式两种不同的热分散系统.辊式热分散主要应用的是转轴对纤维胶粘物的高温搓揉、疏解作用,将其分散成团,再通过精筛除去,除去胶粘物的温度区为95℃左右;盘式热分散系统通过剪切力将纤维胶粘物分离、细化,分离纤维和胶粘物的最佳温度区是110～120℃.比较而言,盘式热分散系统对胶粘物的分散效果更好.同为盘式热分散系统,Kvaerner公司的产品较CELL WOOD公司在国内得到了较快的推广应用.     

The influence of lactic acid fermentation process of red beet juice on the stability of biologically active colorants

Lactic acid fermentation can have preservative effect on red beet juice. The behavior of the pigment in the fermented juice was investigated and the results were compared with those of non-fermented juice. Two red beet varieties (Czerwona Kula and Chrobry) were used in our experiment. Three probiotic bacteria and three infant intestinal microbiota of Lactobacillus sp. were selected for beet juice fermentation.Lactic acid fermentation influenced both red and yellow pigments. In the two beetroot varieties (Chrobry and Czerwona Kula) studied, the dominant red-violet pigment components were betanin, isobetanin, while vulgaxanthin I was the major yellow pigment. Betanin was the main red-violet component in juices before fermentation. After fermentation also betanidin and isobetanidin were observed. Huge amounts of betanidin were found especially in fermented Chrobry juice.It was observed that fermented juice from Chrobry cultivar contained higher betanidin than betanin levels. Contrarily, in juice from Czerwona Kula cv., betanin level was much higher than betanidin level.