Influence of γ-irradiation and ice storage on fat oxidation in three Indian fish

The influence of low-dose γ-irradiation (up to 5 kGy) on fat oxidation in skin and flesh fractions of some commercially important fishes (Indian mackerel, white pomfret and seer) during ice storage was examined. Thiobarbituric acid (TBA) values increased in both control and irradiated fish particularly in mackerel and seer meat. In mackerel, the TBA values declined towards later part of storage. Pomfret skin, but not mackerel and seer skin, showed radiation-induced oxidation, which increased further during ice storage.     

The response of unripe Conference pears to modified atmosphere retail packaging

Unripe green Conference pears with initial firmness values of 46–55 N were sealed in modified atmosphere (MA) low density polyethylene (LDPE, 30μ) pillow packs and in perforated control packs on three dates during 1985–1986. Changes in pack atmosphere composition, skin chlorophyll content, flesh firmness and sensory quality were monitored during 14–20 days simulated shelf-life at 20°C. In MA packs, equilibrated atmospheres containing 5–9% CO₂ and < 5% O₂ developed within c. 3 days. Chlorophyll degradation was completely inhibited by MA and resumed when packs were perforated, but MA only partially retarded the rate of flesh softening. Variations in the rate of ripening changes in duplicate MA packs could not be explained simply by differences in pack atmospheres. Furthermore, pears retarded by MA packaging failed to develop the normal sweet, aromatic flavour and succulent, juicy texture of 'eating-ripe' fruit, even when the packs were perforated after 4 days.
The differences in the responses of pears and apples to MA packaging, and the limitations of using this technique for the commercial marketing of English pears are discussed.     

Electron-beam Irradiation Preserves the Quality of White Button Mushroom (Agaricus bisporus) Slices

ABSTRACT: The effect of electron-beam irradiation on microbial counts, color, texture, and enzyme activity of mushroom slices was evaluated at dose levels of 0.5, 1, 3.1, and 5.2-kGy. Irradiation levels above 0.5 kGy reduced total plate counts, yeast and mold, and psychrotrophic counts to below detectable levels and prevented micro-bial-induced browning. Firmness of all samples was similar during storage except for the 5.2-kGy sample. Color was preserved by irradiation as evidenced by the higher L values. Electron-beam irradiation at these levels did not affect the polyphenol oxidase activity. Irradiation at 1 kGy was most effective in extending shelf-life of mushroom slices.     

Effect of Vacuum and Modified Atmosphere Packaging on the Shelf-life of Liquid-smoked Swordfish (Xiphias gladius) Slices

ABSTRACT: Swordfish fillets, dry-salted and treated with liquid smoke, were sliced and packed in vacuum conditions and under modified atmosphere (MA) (5% O₂,45% CO₂, 50% N₂) and stored at chilled temperature (4°C) to determine the effect of different packaging on shelf-life. Sensory attributes, total volatile basic nitrogen (TVB-N), pH, lipid oxidation by thiobarbituric acid test, and microbiological counts were monitored during 45 d of storage. The TVB-N increased to levels recommended by European regulation at the time of sensory rejection, resulting as the most reliable parameter of quality decay. Lipid oxidation was low and microbial counts could not be correlated with quality decay. Sensory rejection (at least 50% of the assessors scoring =5 in a scale from 1 to 9) was sooner for MA-packed samples (12d) than for vacuum-packed ones (42d).     

A novel compound, 7,10-dihydroxy-8(E)-octadecenoic acid from oleic acid by bioconversion

Sixty-two cultures from the Agricultural Research Service (ARS) Culture Collection and 10 cultures isolated from soil and water samples in Illinois were screened for their ability to convert agricultural oils to value-added industrial chemicals. A new compound, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD), was produced from oleic acid at a yield of greater than 60% by bacterial strain PR3 which was isolated from a water sample in Morton, IL. To our knowledge, DOD has not been previously reported. The optimum time, pH and temperature for the production of DOD were 2 days, 7.0, and 30°C, respectively. The production of DOD is unique in that it involves hydroxylation at two positions and rearrangement of the double bond of the substrate molecule.     

Modified atmosphere packaging of a mixed prepared vegetable salad dish

The aim of this study was to design a modified atmosphere package for a mixed vegetable salad consisting of 75 g of cut carrot, 55 g of cut cucumber, 20 g of sliced garlic and 50 g of whole green pepper. Respiration data of all the components were combined with film permeability data to predict package atmospheres and design optimal packages for experimental testing for improved shelf-life of the produce. The optimal package avoided minimum O₂ and maximum CO₂ tolerance limits, and chilling injury temperatures for any component. A pouch form package made of 27 mm low density polyethylene developed a modified atmosphere of 2.0–2.1% O₂ and 5.5–5.7% CO₂, which was beneficial for all components and provided better quality retention than other test packages.     

Review: Modified Atmosphere Packaging and its effects on the microbiological quality and safety of produce

Modified Atmosphere Packaging and related technologies are increasingly used to extend shelf-life of fresh produce. This paper reviews the effect of such technology on the spoilage microbiological flora and food-borne pathogens which may be present in produce and also on the organoleptic properties of the product.     

Fundamentals of stability testing

The principles on which stability tests are based are reviewed. The need to differentiate between product stability and product-container compatibility is emphasized. Recognition of this distinction is fundamental to the efficient organisation and execution of stability tests.
Attention is also drawn to the desirability of having for every product a release specification with which it must comply when manufactured and a broader check specification with which it must comply throughout its shelf-life.
Test methods and the interpretation of the data accrued throughout a test are also discussed.
It is concluded that stability tests should not be conducted in accordance with a standardized routine pattern but that the objectives of each test should be defined and the test designed to achieve those objectives in the most efficient way.
Les regles fondamentales des essais de stabilite     

复合天然保鲜刹在低温肉制品保鲜中的应用试验

针对当前低温肉制品的保鲜难题，本试验利用丹尼斯克复合天然保鲜剂葆先丹PM21，在肉制品工厂烟熏烤肠中试中同现有的肉制品保鲜方案进行应用比较。恒温保藏研究证实，葆先丹PM21肉制品保鲜剂性能显著优于同类产品，在50天内能有效抑制低温烤肠微生物数量在国家标准范围之内，同时样品感官质量保持良好，具有良好的防腐性能价格比。