Effects of Anti-browning Combinations of Ascorbic Acid, Citric Acid, Nitrogen and Carbon Dioxide on the Quality of Banana Smoothies

The effects of 0.2 % ascorbic acid?+?0.2 % citric acid (AA?+?CA), 0.2 % ascorbic acid?+?0.2 % citric acid?+?N₂ (AA?+?CA?+?N₂) and 0.2 % ascorbic acid?+?0.2 % citric acid?+?CO₂ (AA?+?CA?+?CO₂) on the quality of banana smoothies were investigated. An obvious anti-browning effect was observed after each treatment, which resulted from a significant decrease in the polyphenol oxidase activity (p?<?0.05) and the exclusion of oxygen by infusion with inert N₂ or CO₂. The AA?+?CA?+?N₂ treatment exhibited the lowest change of browning index (ΔBI) indicating the best anti-browning effect on the banana smoothies. Compared with the Herschel–Bulkley model, the Power Law was less complex and more suitable for describing the rheological properties of the banana smoothies. AA?+?CA, AA?+?CA?+?N₂ and AA?+?CA?+?CO₂ treatments all significantly increased the pectin methylesterase activity of the banana smoothies (p?<?0.05). The AA?+?CA treatment increased the cumulative volume of the larger particles in the banana smoothies. The viscosity of the banana smoothies decreased after the three different treatments. In terms of the comprehensive results, the inclusion of AA?+?CA?+?N₂ in the production of banana smoothies was the best processing method applied.     

Heated Ascorbic/Citric Acid Solution as Browning Inhibitor for Pre-Peeled Potatoes

Treatment of pre-peeled potatoes with heated ascorbic acid (AA)/citric acid (CA) solution to extend shelf-life was investigated. Potatoes were abrasion or high pressure steam peeled, heated for 5–20 min in 1% AA + 2% CA at 45–55°C cooled, and then dipped for 5 min in browning inhibitor (BI) solution containing 4% AA +1% CA +1% sodium acid pyrophosphate. Combined treatment inhibited potato discoloration for 14 days at 4°C compared to 3–6 days with BI treatment alone. Raw material and treatment conditions were selected to minimize graying and textural abnormalities encountered with some treatments. Treatment with heated AA/CA may be an alternative to use of sulfites to control browning in pre-peeled potatoes.     

速冻苹果片加工工艺研究

本文比较了浓度为0.5%的柠檬酸、0.005%的偏重亚硫酸钠、0.1%的抗坏血酸和0.9%的氯化钠溶液对苹果片的防褐变效果,并以速冻苹果片的食用品质和冻耗为依据,对其速冻工艺进行了优化,得到速冻苹果片的最佳制备工艺为:苹果片厚度为6mm,0.9%氯化钠溶液中浸泡5 min,速冻时的风速为6m/s.在此条件下得到的速冻苹果片的硬度适中,有甜的口感和苹果风味,口感评价得分16.86分(满分20分).     

柠檬酸处理对小麦面筋蛋白酶解特性的影响

以复合蛋白酶为水解酶,试验研究了小麦面筋蛋白酶解前柠檬酸预处理对其酶解特性的影响.通过单因素试验和正交试验确定柠檬酸预处理的最佳工艺条件为:柠檬酸浓度为0.1%(m/V),温度为50℃,处理时间为30min.同时研究了柠檬酸处理后小麦面筋蛋白在酶解过程中的水解度和蛋白提取率的变化规律.     

柠檬酸：酸味之源

在夏日口渴难忍之际，来上一瓶冰凉酸甜的饮料，立刻便减缓了暑热进入体内的脚步。这种酸酸的可口味道是来源于哪里呢？让我们来看看饮料的成分列表，众多不同饮料中同一成分——柠檬酸一定会映入你的眼帘，想一下柠檬的酸劲，便可认定酸味源自于它。不错，柠檬酸的确是作为酸来使用的，被叫做酸味剂，其实除了带来酸酸的口感，柠檬酸还附带起到其他的作用。让我们一起来认识这种运用广泛的酸。[编者按]     

金黄色苹果干的研制

以市售的红富士苹果为原材料,制备金黄色苹果干。对苹果切片、熏硫、糖渍、干燥等情况进行比较,通过单因素试验及均匀设计实验得到最佳工艺条件为亚硫酸钠浓度0.3%、熏硫时间80min、干燥温度75℃、干燥时间2.5h,制得的苹果干色泽金黄均匀,酸甜适口,具有苹果清香的特征。     

Optimization of Nutrient Retention During Processing: Ascorbic Acid in Potato Dehydration

A kinetic model representing ascorbic acid degradation in potatoes as a function of moisture content and temperature was used to find optimal dryer-temperature control paths for minimizing ascorbic acid loss during air drying of potato disks. Optimal dryer-temperature control was also determined for minimizing drying time given a specified minimum retention of ascorbic acid. Constraints were placed on the final moisture content and the air temperature. Optimization was achieved using a simulation-optimization approach based on the complex method.     

柠檬酸及饮料中配制成分的急性毒性

为进一步弄清不同产地柠檬酸的毒性，以防中毒事件发生，对不同厂家生产的医用和食用柠檬酸进行了小鼠急性毒性(LD50)实验筛选。结果证明：同一类产品的毒性不同，这可能与柠檬酸重金属螯合物的含量有关。     

Influence of System Composition on Ascorbic Acid Destruction at Processing Temperatures

The anaerobic L -ascorbic acid (AAs) destruction in glucose aqueous model systems (water activity, a_w, 0·94) of pH 3·5, 4·1 and 5·0 was studied. The AAs degraded as a function of time and temperature (70, 80 and 90°C) with a behaviour that, in general, could be described by first order kinetics except for AAs in the system containing L -lysine, in which the results adjusted to zero order. The increment of pH from 3·5 to 5·0 accelerated AAs destruction and browning reactions. The addition of tin(II) or lysine to the glucose medium, increased AAs loss and browning. No difference was observed in AAs degradation and colour intensity when sorbic or propionic acid were used as antimycotics, at pH 3·5. Packaging the glucose system of acid pH with an air chamber, produced a faster destruction of AAs and browning of the solution than the one observed for the same system in anaerobic condition. In aerobic condition, the presence of glucose produced a lesser degradation of AAs than the one observed in the system without humectants. © 1997 SCI     

Ascorbic Acid Retention in Shredded Iceberg Lettuce as Affected by Minimal Processing

The effects of slicing method, packaging atmosphere and storage temperature were determined on total ascorbic acid (TAA) content of modified atmosphere packaged shredded lettuce. TAA was extracted from the lettuce samples and levels were monitored using either titration with 2,6-dichlorophenolindophenol solution or an assay kit. Slicing affected (p<0.05) ascorbic acid retention in the order manual tearing > manual slicing > machine slicing. Flushing with 100% nitrogen increased retention (～5%, p<0.05) over packages with product modified atmospheres. Storage at 3°C increased retention (～20%, p<0.05) compared with storage at 8°C. Scores for product appearance generally followed losses of TAA in the lettuce (p<0.05).     

Modeling Respiration of Apple Slices in Modified-Atmosphere Packages

Modified-atmosphere packaging was used to provide respiratory data for apple (Malus xdomestica Borkh.) slices at 0, 5, 10 and 15°C. The maximum rate of O₂ uptake increased with increasing temperature. The lowest O₂ partial pressure to which fruit could be exposed without fermentation also increased with increasing temperature. A mathematical model of film permeability data characterized the effect of fruit mass, film permeability to O₂, activation energy of O₂ permeation, temperature, and the film type, area, and thickness on O₂ partial pressure for hermetically packaged apple slices. The model identified a minimum (fruit mass filmthickness)/(film area) ratio for apple slices, which would simplify package design calculations.     

Characterizing the Variability of Enzymatic Browning in Fresh-Cut Apple Slices

Browning reaction variability in apple slices was characterized using a new procedure denominating the differential pixel method. Using this method, a kinetic rate and an empirical order of reaction were derived for each pixel in an image corresponding to a sliced apple surface undergoing browning; each pixel in the image can be seen as a small portion of the fruit. In the experiments, 40 samples of fresh-cut apple slice were put on a computer vision system and images recorded over time at a room temperature of 5 °C. Data was fitted to the Weibullian model kinetic. Results confirmed strong heterogeneity in the values of enzymatic browning kinetic rate on the apple surface; this variability was characterized as a normal logarithmical distribution, with a mean rate kinetic value of the ?0.0117?±?0.0036 units of L* decayed per minute. The empirical order of reaction was distributed on the surface following a normal statistical distribution with a mean equal to 0.451?±?0.046. No statistical differences were established in the kinetic rate and in the empirical order when the differential pixel method was compared with the traditional method (where a mean of the L* intensity value was used).     

柠檬酸的热解特性

使用热失重/傅里叶变换红外联用( TG-FTIR)技术研究了柠檬酸的热裂解特性,测定并比较了不同氧气浓度下柠檬酸的热重(TG)和微商热重(DTG)曲线,以及柠檬酸热解气相产物相对含量和生成规律,探讨了柠檬酸可能的热解机制.结果表明:①柠檬酸的热解气相产物主要有CO2,CO,H2O,酸酐和酮类物质.CO2是气相产物中相对含量最高的物质,CO最低;水最早出现在气相产物中,酸酐是最后存在于气相产物中的物质;②柠檬酸可能有2种主要热解途径:先脱水后脱CO2的酸酐生成模式和主要脱CO2的酮生成模式.在热解初期,2种模式同时发生,氧气浓度的增加有利于酮的生成.在较高温度下,主要以酸酐生成模式为主.     

Changes in Peroxidase Activity, Hexanal, Ascorbic Acid and Free Sulfhydryl in Blanched Asparagus During Frozen Storage

Asparagus spears were water blanched at 88°C for 1 to 4.5 min and stored at - 18°C. Hexanal, ascorbic acid, free sulfhydryl and peroxidase activity were monitored during storage. Blanching for 2 min resulted in a 98% reduction in peroxidase activity. No hexanal was detectable in product blanched for 2 min or longer. Ascorbate stability during storage increased with increase in blanching time although not in direct relation to peroxidase activity loss. Free sulfhydryl was sensitive to heating and also decreased during storage of unblanched asparagus. However, there appeared to be a stable fraction of free sulfhydryls.     

柠檬酸中红外光谱研究

采用中红外(MIR)光谱技术对柠檬酸的结构开展研究.实验发现,柠檬酸的主要红外吸收官能团包括VC = O-柠檬酸、δCH2-柠檬酸、βOH-柠檬酸、VC-O-柠檬酸和γOH-柠檬酸.本研究拓展了中红外光谱技术在结构研究中的应用范围,具有重要的应用价值.     

Vacuum Packaging, Ascorbic Acid and Frozen Storage Effects on Heme and Nonheme Iron Content of Mackerel

Vacuum packaging and ascorbic acid were tested for their ability to prevent heme iron loss in mackerel (Scomber scombrus). Vacuum packed samples had less heme breakdown than air packed samples at frozen storage temperatures above ?20°C. Ascorbic acid protected the heme at all temperatures when compared to air or vacuum packed samples.     

Rheological Studies During Submerged Citric Acid Fermentation by Aspergillus niger in Stirred Fermentor Using Apple Pomace Ultrafiltration Sludge

Rheological profile studies for apple pomace ultrafiltration sludge (APS) broth with filamentous fungus, Aspergillus niger NRRL-567 during citric acid (CA) fermentation are reported for the biomass developed in a 7.5 l bench scale fermentor. CA bioproduction of 23.67?±?1.0 g/l APS and 40.34?±?1.98 g/l APS was obtained in control (120 h) and in treatment with inducer, MeOH 3% (v/v), respectively, after 132 h of fermentation by A. niger NRRL 567. The rheological properties of the fermentation broth including pellets were analyzed. The control demonstrated non-Newtonian pseudoplastic behaviour due to more filamentous growth. However, in treatment supplemented with inducer (methanol), pellet form was observed during fermentation with less viscous non-Newtonian broths. The power law model was followed with good confidence of fit (77.8–88.9%) throughout the fermentation in treatment with MeOH as an inducer. However, power law was followed with moderate fit of confidence (65.3–75.9%) at the beginning of fermentation until 48 h and later followed a good confidence of fit (75.9–88.2%) until 144 h of fermentation in control. Important rheological changes occurred in the broth during maximal CA production phase along with increase in biomass in the pelleted mycelium form.     

Control of Enzymatic Browning in Apple with Ascorbic Acid Derivatives, Polyphenol Oxidase Inhibitors, and Complexing Agents

Novel browning inhibitors were evaluated in raw apple juice and on the cut surface of apple plugs, using quantitative measurements of color changes during storage to assess treatment effectiveness. Ascorbic acid-2-phosphate (AAP) and -triphosphate (AATP) showed promise for cut surfaces but were ineffective in juice. Ascorbic acid-6-fatty acid esters showed anti-browning activity in juice. Cinnamate and benzoate inhibited browning in juice but induced browning when applied to cut surfaces. Combinations of β-cyclodextrin with ascorbic acid (AA), AAP or ascorbyl palmitate were effective in juice but not on cut surfaces. Combinations of AA with an acidic polyphosphate were highly effective with both juice and cut surfaces.     

Quality of Minimally Processed Apple Slices from Selected Cultivars

Twelve cultivars were prepared as slices and stored 12 days at 2°C. Changes in respiration and quality factors were compared. Initial respiration rates among cultivars varied from 3.5 mL CO₂/kg/hr in Delicious to 7.6 mL CO₂/kg/hr in Monroe and decreased rapidly during the first 3 days. Idared, McIntosh, Delicious, and Rome showed relatively low respiration throughout storage. Firmness of slices during storage decreased gradually for 7 days and more rapidly thereafter. Empire, Golden Delicious, and Idared apples showed minimum changes in firmness. Change in color of slices was rapid during the first 3 days. Cortland. Emuire. Golden Delicious. New York 674. and Delicious showed least browning. Titratable acidity, pH, soluble solids, and weight changes during storage were small and varied by cultivar. NY674, Cortland, Golden Delicious, Empire, and Delicious showed more desirable attributes for minimal processing.