Processing and Frozen Storage Effects on the Iron Content of Cod and Mackerel

Processing and subsequent frozen storage affected the iron content of cod (Gadus morhua) and mackerel (Scomber scombrus) muscle tissue. Frame mince was obtained from the bone rack, without the head or viscera remaining, after filleting. Frame mince had significantly higher iron levels than intact fillets with or without skin or fillets that were subsequently minced. Skin-on fillets had more iron than skin-off fillets. Cod frame mince had about 50% heme iron, while mackerel frame mince ranged from 20-64%. Nonheme iron increased during frozen storage due to heme breakdown. Storage above ?14°C was more deleterious to the heme molecule than lower temperatures (?20°C or ?40°C).     

Effects of Processing and Storage on the Water-Soluble Vitamin Content of Human Milk

Effects of four heat treatments (62.5°C, 30 min; 72°C, 15 sec; 88°C, 5 sec; and 100°C, 5 min) and frozen storage (?20°C, 4 wk) on water-soluble vitamin content of composite samples of mature human milk were determined. No changes in riboflavin, biotin, and total pantothenic acid content were observed after any of the treatments. Heating at 100°C for 5 min decreased thiamin, vitamin B₁₂, and vitamin C contents. Vitamin Bs content was reduced by heating at 88°C and 100°C. Free folate was not affected by heating while total folate concentration was decreased similarly by all heat treatments. During frozen storage at ?20°C, niacin and free pantothenic acid concentrations were reduced; riboflavin, vitamin Bs, biotin, total pantothenic acid, vitamin C, and vitamin B₁₂ were unaffected; while measurable thiamin and free folate concentrations increased. Overall, the two lower temperature treatments were less detrimental to the water-soluble vitamins in human milk.     

Effects of High-Intensity Pulsed Electric Fields Processing Parameters on the Chlorophyll Content and Its Degradation Compounds in Broccoli Juice

The influence of high-intensity pulsed electric fields (HIPEF) parameters including electric field strength (15–35 kV/cm), treatment time (500–2,000 μs), and polarity (monopolar or bipolar mode) on the content of chlorophylls (Chls), pheophytin (Phe), chlorophyllide (Chlide), and pheophorbide (Phb) and chlorophyllase activity (Chlase) in broccoli juice were assessed. A significant effect of HIPEF parameters on Chlase, Chls, and Chls degradation compounds was observed through a response surface methodology design. However, polarity did not exert influence neither on Chl a nor on Chl b. The optimum HIPEF treatment was found to be 35 kV/cm for 1,980 μs in bipolar mode, where the highest content of Chls was kept, the lowest Chlase residual activity was reached, and the minimal quantities of Chls degradation compounds content were formed. Additionally, at these HIPEF conditions, broccoli juice exhibited greater content of Chls than thermally treated or untreated juice. These outcomes demonstrated that HIPEF processing could be a suitable technology to maintain the Chls content in broccoli juice.     

Effects of Processing on Zinc Levels in Spinach, Beef, and Potatoes

Spinach, beef, and potatoes were subjected to combinations of cooking, freezing, retorting, and storage and analyzed for total zinc and water soluble zinc, before and after acid-enzyme digestion. Zinc and its complexes that were soluble were membrane filtered to exclude the passage of substances larger than 5,000 daltons. Approximately 30–50% of the total zinc in spinach systems and about 70–100% of the zinc in potato systems was water soluble. Practically none of the endogenous zinc in beef was water soluble. Regardless of processing method, essentially all zinc in spinach and potatoes and about half of the zinc in beef was released after acid-enzyme digestion. All of the spinach and potato zinc and at least a third of the beef zinc following digestion passed through the 5,000 dalton membrane.     

Effects of Simulated Retail Display and Overnight Storage Treatments on Quality Maintenance in Fresh Broccoli

The quality of fresh broccoli during simulated retail display was evaluated using contact (ice) and air cooling separately and in combination. Chlorophyll and ascorbic acid were best maintained with air cooling, while weight was best maintained with ice cooling alone. In air-cooled display units, ice placed both on top of and beneath broccoli heads resulted in more rapid loss of chlorophyll and ascorbic acid than did bottom-icing alone. Bottom-iced broccoli in air-cooled units kept best overnight if left in place and covered with wet burlap. Removal to a 4°C walk-in cooler each night resulted in good color retention and marketability but weight loss after 4 days was significantly higher.     

机械损伤及二氧化氯对菠菜硝酸盐和贮藏 品质的影响

为了研究机械损伤及其二氧化氯(ClO_2)处理对菠菜贮藏过程中硝酸盐含量及贮藏品质的影响,用50 mg/L二氧化氯分别对机械损伤和未损伤的菠菜进行处理,测定了菠菜贮藏过程中硝酸盐、亚硝酸盐、硝酸还原酶、可溶性固形物、叶绿素和维生素C含量的变化。结果表明:机械损伤对菠菜中硝酸盐含量和贮藏品质影响明显,尤其对硝酸盐、可溶性固形物和维生素C含量影响显著。ClO_2处理可以有效减缓硝酸盐的生成,提高菠菜的贮藏品质。     

水分含量对花生仁储藏过程中的品质影响研究

通过花生仁露空储藏与真空储藏的加速对比试验,研究了不同水分含量的花生仁水分活度、过氧化值、酸价的变化趋势,试验结果表明,初始湿基湿含量为5.15%的样品较其他样品具有更好的储藏特性,真空包装样品过氧化值在整个储藏期增加46.23%,酸价增加56.79%,/较其他水平样品增幅减少约60%以上.研究发现,花生仁的水分含量过...     

不同干燥方法对西兰花中萝卜硫素含量影响

采用阴干、50℃~90℃烘干及晒干三种常用干燥方式干燥西兰花的花、茎、叶,采用HPLC测定萝卜硫素含量。西兰花不同部位中萝卜硫素含量是种子>花>茎>叶;而不同干燥方法中烘干最好,阴干最差,5种烘干温度中以90℃烘干时萝卜硫素含量最高。西兰花不同部位中种子萝卜硫素含量最高,有10.48 mg/g;而干燥方式采用90℃烘干最佳。     

VC磷酸酯在虾料生产和储存过程中的含量变化研究

利用高效液相色谱法对VC磷酸酯在虾料生产和储存过程中的稳定性,包括VC磷酸酯在混合、超微粉碎、调质、制粒、后熟化和打包等工艺环节和储存15、30、40、50、60、70、80、90 d的含量变化进行了研究。结果表明:不同工艺环节对VC磷酸酯的破坏程度不同,其大小依次为调质后熟化制粒超微混合打包,其中调质过程造成的损失率高达6.86%~8.95%,经过虾料生产过程VC磷酸酯保存率为64.41%~75.93%。VC磷酸酯在虾料储存过程中含量逐渐下降,在3个月的储存期内,保存率在88.36%~91.33%之间,平均每月损失率为2.89%~3.88%。不同厂家生产的VC磷酸酯稳定性存在差异。     

不同加工处理方式对枸杞色素的影响

色素作为枸杞的主要功效成分之一,其含量除与枸杞品种、气候和产地等采前因素有很大关系外,很大程度上受到加工及贮藏条件的影响。本文首先论述了枸杞中主要色素组成以及不同产地、成熟期枸杞中色素含量的差异,然后讨论了不同的干制方法、制汁过程以及贮藏等不同处理方式对枸杞色素的影响,最后展望了枸杞色素的发展前景。     

Black Currant Nectar: Effect of Processing and Storage on Anthocyanin and Ascorbic Acid Content

The degradation of anthocyanins and ascorbic acid in black currant nectar was studied during processing and storage. A continuous production process was used where the nectar was bottled within 4.0h; 20% of both components were lost in the main stream process. The choice of enzyme mainly affected the recovery of ascorbic acid. Pasteurization resulted in a loss of 2-6 % of the ascorbic acid content. About 50% of the original content of monomeric anthocyanins remained after 6 months storage at 20°C. The stabilities of delphinidins and cyanidins during storage were very similar. Deaeration of the nectar before bottling had no effect on anthocyanin content.     

储藏时间对不同种类蔬菜中亚硝酸盐含量的影响

亚硝酸盐是蔬菜中主要有害物质之一,长期食用亚硝酸盐含量高的蔬菜将严重影响人的身体健康.本研究旨在通过对不同储藏时间蔬菜中亚硝酸盐含量的测定,明确储藏时间对各类蔬菜中亚硝酸盐含量的影响.基于重氮化耦合反应原理,利用改良的分光光度法测定了10类主导蔬菜在储藏0、1、2、3d后的亚硝酸盐含量,结果显示:预处理阶段活性炭的使用可以显著提高对蔬菜中亚硝酸盐含量的检测精度.亚硝酸盐在新鲜蔬菜中含量最低,但随着储藏时间的延长,亚硝酸盐含量在各类蔬菜中均有不同程度提高,其中油菜、小白菜、韭菜、芹菜等叶菜类亚硝酸盐的最终含量显著高于黄瓜、土豆、萝卜、大蒜等根茎类蔬菜.因此,在购买蔬菜时,应尽量选择新鲜蔬菜和根茎类蔬菜,减少亚硝酸盐对健康的不良影响.     

Ozone Storage Effects on Anthocyanin Content and Fungal Growth in Blackberries

Ozone exposure was assessed for storage of thornless blackberries which are prone to fungal decay. Blackberries were harvested and stored for 12 days at 2°C in 0.0, 0.1, and 0.3 ppm ozone. Berries were evaluated for fungal decay, anthocyanins, color and peroxidase (POD) activity. Ozone storage suppressed fungal development for 12 days, while 20% of control fruits showed decay. The main mold was Botrytis cinerea. Ozone storage did not cause observable injury or defects. By 12 days, anthocyanin content of juice was similar to initial levels for all treatments. Surface color was better retained in 0.1 and 0.3 ppm-stored berries by 5 days and in 0.3 ppm berries by 12 days, by hue angle values. POD was greater in controls and 0.1 ppm samples, and was lowest in 0.3 ppm fruits by 12 days. Ozone storage resulted in market quality extension.     

Cultivar, Processing, and Storage Effects on Pecan Kernel Color

Pecan kernels of two cultivars (Cheyenne and Wichita) and two trial selections (61–6–67 and 49–1478) were evaluated for color differences before and after processing by three methods (chlorine soak, hot water, and steam) and during 15 wk storage at 21°C and 65% RH. Hunter color values varied significantly among cultivars before processing. Significant cultivar and treatment differences were observed after processing and during storage. Kernels of all cultivars subjected to hot water and steam treatments were darker and redder in color after processing and after all storage times than the control (untreated) kernels and those subjected to the chlorine soak method.     

贮藏及热处理对桑葚酒中多酚类物质含量的影响

为研究桑葚酒在4,25和45℃的贮藏温度下贮藏10 d后多酚类物质含量的变化情况,通过检测总酚含量、总黄酮含量、花青素保留率、羟基自由基清除率四个指标来确定桑葚酒的最佳贮藏温度。通过对桑葚酒进行热处理,检测桑葚酒在60,70和80℃的温度下花青素保留率随加热时间的变化规律。结果表明:桑葚酒适宜在25℃的贮藏温度下贮藏;桑葚酒在热处理过程中的花青素保留率随热处理温度的提高和加热时间的延长而下降,桑葚酒中花青素热降解动力学模型符合一级反应规律,动力学方程为t=(lnC0-lnCt)/[(1.71×10^5)×exp(-5014.43/T)。此次研究为桑葚酒的贮藏和生产开发提供了一定理论基础。     

Processing, Packaging, and Storage Effects on Quality of Freeze-Dried Strawberries

Water sorption isotherms of freeze-dried strawberries were determined using the interval sorption technique. The surface temperature during freeze-drying (from 20°C to 60°C) affected the hygroscopicity of the strawberries, particularly below 0.40 a_w. Over 1 yr, quality changes in dried strawberries were evaluated by sensory analysis at 3-month intervals. Crushing before drying and low processing temperatures improved sensory quality of dried strawberries and vacuum packaging improved storage stability.     

西兰花叶加工保健茶工艺研究

ZHAO Yuan-shou;DU Xi-mei;SU Xiao-hong;GAO Guo-qiang(Lanzhou Industrial Research Institute,Lanzhou 730050,China)     

西兰花贮期黑斑病病原菌鉴定及防治技术研究

西兰花贮期主要病害是黑斑病,经病原菌鉴定,属芸苔生链格孢菌。4℃的低温只能抑制而不能终止该菌的生长,而35℃可有效抑制该菌的生长。pH在5~9的范围内菌落生长良好,pH低于3和高于11时该菌几乎完全受到抑制。臭氧和减压均能抑制该病原菌的生长,浓度为300 mg/m3的臭氧杀菌效果显著,浓度再增高,杀菌效果与300 mg/m3差异不显著,在101~20 kPa的压力范围内,压力越低,抑菌效果越好,以压力40 kPa较为理想。