Quality changes during refrigerated storage of MA-packaged pre-rigor fillets of farmed Atlantic cod (Gadus morhua L.) using traditional MAP, CO2 emitter, and vacuum

ABSTRACT:  Quality changes during 3 wk of refrigerated storage (1.3 °C) were studied on pre -rigor filleted farmed Atlantic cod packed in modified atmosphere (MAP, 60% CO₂ and 40% O₂) or vacuum. The packages of MAP contained either a CO₂ emitter and low gas volume to product volume (g/p ratio) of 1.3, or a 3.9 g/p ratio and no emitter. The CO₂ level remained stable or increased in the packages with CO₂ emitter, whereas the CO₂ level in the packages with no CO₂ emitter decreased to 40% after 4 d of refrigerated storage. High levels of oxygen in the gas mixture prevented formation of trimethyl amine (TMA) during storage of the MA-packed fish, whereas the TMA content increased significantly after 10-d storage in vacuum. MA-packed samples had the highest values of 1-penten-3-ol. Sensory scores of sour, sulfur, and pungent odors were significantly higher for vacuum-packed cod compared to the 2 MA-packaging methods measured 14 d after slaughtering. No differences in sensory scores were observed between the 2 methods of MAP, and shelf life of these samples seemed to be 14 to 21 d. Cod samples packaged in vacuum packages had higher pH values compared to ordinary MAP and packages containing a CO₂ emitter. Bacterial growth was inhibited by MAP and resulted at the end of the storage period in dominance of Carnobacterium and some Photobacterium . In MA packages with high O₂ levels the Photobacterium was inhibited. It is concluded that CO₂ emitters are well suited for reduction of transport volume for MA-packaged farmed cod.     

Survival and Growth of Salmonella hadar on Minimally Processed Cabbage as Influenced by Storage Abuse Conditions

Shredded, washed and centrifuged cabbage was packaged in monooriented polypropylene (OPP) bags, inoculated with Salmonella hadar and stored 10 days at 4°C, 12°C and 20°C. Microbiological, appearance, odor and headspace gas analysis were evaluated throughout storage. S. hadar and mesophilic aerobic and psychrotrophic microorganism growth was affected by storage time and temperature. S. hadar counts were lower (p<0.05) at 4°C than at 12°C and 20°C. The score ratings for general appearance, wilting, browning and off-odor showed that all samples were commercially acceptable. Results indicated that S. hadar could survive and proliferate on minimally processed cabbage, thereby posing a potential hazard to consumers.     

Internal Modified Atmospheres of Coated Fresh Fruits and Vegetables: Understanding Relative Humidity Effects

ABSTRACT: Internal atmosphere modification in fruits and vegetables by surface film coatings depends on film permeability, coating thickness, and fruit surface coverage. Research in this area has been mostly empirical, with unpredictable results and diverse conclusions. To reduce variability, it is necessary to have a better understanding of factors that may influence the response of coatings applied to fruits. One factor is relative humidity (RH), which is known to affect the permeability of biopolymer films. By using steady-state mathematical models as tools, we hypothesize that fruits coated with hydrophilic films will be largely influenced by the RH of storage conditions. For hydrophobic materials, RH would have less influence on coating performance.     

Combined Application of Antibrowning,Heat Treatment and Modified‐Atmosphere Packaging to Extend the Shelf Life of Fresh‐Cut Lotus Root

This work aimed to determine the effects of different concentrations of antibrowning treatments (that is, distilled water [DW], 1% ascorbic acid [AA], 0.5% chamomile [CM], and 1% AA + 0.5% CM) and heat‐treatment (55 °C for 45 s) combined with packaging under 4 different modified‐atmosphere gas compositions (that is, air, vacuum, 100% CO₂, 50% CO₂/50% N₂) on the quality and microbiological characteristics of fresh‐cut lotus root. The quality characteristics (that is, color, weight loss, texture, pH, polyphenoloxidase activity, and total phenolic content) of the AA + CM‐dipped sample in 100% CO₂ packaging were maintained significantly better than those of the other samples (P < 0.05). The microbiological counts observed in the DW‐dipped sample during storage were higher than those of the AA, CM, and AA + CM samples, and heat‐treatment retarded the microbiological deterioration of fresh‐cut lotus root. Therefore, the results revealed that dipping in an antibrowning treatment (AA + CM), and 100% CO₂ MAP with heat treatment effectively extend the shelf life of fresh‐cut lotus root to 21 d at 5 °C.     

Nutrient content of whole cottonseed

The objective of this study was to determine if the nutrient and gossypol contents and in vitro digestibility of 3 types of genetically modified whole cottonseed differed from traditional whole cottonseed. Samples of seed from traditional (no genetic modifications) and genetically modified varieties of cotton grown in 1999 and 2000 were analyzed. Genetic modifications included the insertion of genes to protect cotton from insect pests (Bt), and damage from glyphosate herbicides (RR), and from both (Bt/RR). Year effects were significant for in vitro dry matter (DM) digestibility, gossypol, DM, crude protein (CP), fat, neutral detergent fiber (NDF), acid detergent fiber (ADF), and ash. Higher rainfall resulted in higher CP, fat, and ash and lower NDF and gossypol. There were no differences among seed types for ground or whole seed digestibility, DM, CP, fat, NDF, ADF, ash, lignin, net energy for lactation, amino acids, total fatty acids, or seed index. Overall, the nutrient content and digestibility of varieties of genetically modified seed were similar to that of varieties of traditional whole cottonseed.     

改性涤纶在梳理过程中静电的控制

介绍了改性涤纶在梳理过程中产生静电的原因以及危害。生产过程中采用以下措施能够控制改性涤纶在梳理过程中静电的影响:变化混配比例,合理加湿给湿保湿,保证温湿度环境,合理优化梳理隔距,合理进行针布选型,减小纤维梳理力,采用良好的吸风系统功能。     

基于C8051F单片机的蒸渗仪测控系统

针对国内现有蒸渗仪测控系统测量精度不高,稳定性差的问题,设计了一种基于C8051F410单片机的新型蒸渗仪测控系统.它采用独立电源供电方式,选用高精度A/D转换芯片,并提出了一种改进型递推平均滤波方式,从软硬件两个方面来提高系统的测量精度.经过反复试验,该蒸渗仪具有测量精度高,稳定性好等特点.     

Intracellular localization of dietary and naked DNA in intestinal tissue of Atlantic salmon, Salmo salar L. using in situ hybridization

There is a continuing interest in the fate of DNA from genetically modified organisms (GMO) in the food chain including the uptake of DNA by intestinal cells from dietary sources containing GM feed ingredients. The objective of this study was to elucidate the uptake and persistence of foreign DNA in the intestinal tract of Atlantic salmon Salmo salar L. using in situ hybridization (ISH) that enables the intracellular localization of the DNA, and polymerase chain reaction (PCR) to verify the ISH results qualitatively. Two salmon intestinal models were employed for the investigations; intestinal tissues were sampled in two models namely (a) in vivo from salmon-fed diets containing 30% GM soybeans or 30% nonGM (nGM) soybeans, and (b) ex vivo from intestinal sleeves incubated using different concentrations of PCR-amplified test DNAs (211 and 305 bp) designed from the 35S promoter/plant DNA junction of the RoundupReady soybean (RRS) genome. Additionally, for the incubation study, the effect of a mucolytic agent dithiothreitol (DTT) and a permeability enhancer sodium deoxycholate (SDA) on DNA uptake were investigated. Both treatments were found to enhance DNA uptake ex vivo. Dietary DNA and PCR-amplified DNA could be visualized by ISH in the salmon intestine with more frequently observed signals in the ex vivo model compared to the in vivo model. All results could be verified by PCR. Dietary DNA was localized in the cell vacuolar system and in lamina propria of the mid intestine. Thus, based on the investigated DNA fragment lengths, this study shows that foreign DNA, can be taken up by Atlantic salmon intestinal tissue.     

Storage of Spinach Under Low Oxygen Atmosphere Above the Extinction Point

The extinction point of spinach was <0.4% but above 0.2% O₂ at 0° and 5°C. Respiration rates were ～2.3 times greater at 5°C than at 0°C and were similar among cultivars. In 0.8% O₂ atmosphere, O₂ uptake of three cultivars was reduced by an average of 53% and CO₂ production was reduced by 35% relative to those stored in air. Deterioration of leaves was reduced by 30 to 54%, while weight loss, color and chlorophyll content were not affected by the 0.8% O₂ atmosphere. Thus O₂ could be allowed to be depleted to 0.8% in modified atmosphere packaging without quality loss due to anoxia.     

Whey Protein Coatings for Fresh Fruits and Relative Humidity Effects

ABSTRACT: Whey protein isolate (WPI) films have proven to be excellent gas barriers in previous studies, making them potential coatings for fresh produce. WPI‐coated apples and controls were stored at 20 °;C under RH's ranging from 54 to 92%. Results showed performance of WPI coatings depended on the environment RH. The internal oxygen was lowered, and carbon dioxide increased with decreasing RH conditions. RH did not affect control fruits. At low RH (about 70 to 80% RH), anaerobic respiration was induced in coated fruits due to low oxygen levels (about 0.025 atm). Controlling thickness and film permeability will allow attainment of the appropriate oxygen and carbon dioxide levels for coated fruit.