Storage Lives Research Articles

Raman spectroscopic study of structural changes in Hake (Merluccius merluccius L.) muscle proteins during frozen storage.

This paper examines changes in the structure and functionality of fish muscle proteins at frozen storage temperatures known to render very different practical storage lives (-10 and -30 degrees C). Apparent viscosity and dimethylamine (DMA) content showed drastic temperature-related differences during storage. Raman spectroscopy revealed the occurrence of some structural changes involving secondary and tertiary protein structures. The changes in secondary structure were quantified, showing an increase of beta-sheet at the expense of alpha-helix structure. The nuC-H stretching band near 2935 cm(-)(1) increased in intensity, indicating denaturation of the muscle proteins through the exposure of aliphatic hydrophobic groups to the solvent. These structural changes were more pronounced at -10 degrees C but occurred at both storage temperatures, whereas changes in apparent viscosity and DMA only occurred in storage at -10 degrees C. The possible utility of these structural changes for quality assessment is discussed.

Quality of Swiss chard produced by conventional and organic methods

The storage lives of Swiss chard produced by conventional and organic methods was investigated. No significant differences were found in the initial populations of yeast, molds (1–3×10 4 CFU/g) and psychrotrophic (1×10 4–1.5×10 5 CFU/g), mesophilic (4×10 3–5×10 4 CFU/g) and lactic acid bacteria (2×10 2 and 1.5×10 3 CFU/g). The evolutions of the population of those microorganisms during storage were also similar for both chards. First-order kinetics after an induction period were found for the degradation of ascorbic acid. Although the rate constant (0.057 days –1) was similar for both chard, the induction period for organic chard (∼10 days) was longer than for conventional chard (∼3 days). No significant differences were found between the water and chlorophyll contents and in pH and titratable acidity of both chards. Sensorial analysis showed that organically produced chard retained turgidity, color and brightness longer than the conventionally produced chard.

Biogenic Amines in Vacuum-Packaged and Carbon Dioxide-Controlled Atmosphere-Packaged Fresh Pork Stored at −1.5°C

Biogenic amines are formed in foods as a result of amino acid decarboxylation catalyzed by bacterial enzymes. When consumed in sufficient quantities, these compounds will cause headache, hypertension, fever, and heart failure. Technologies such as vacuum packaging and carbon dioxide–modified atmosphere packaging (CO2-MAP), when combined with low-temperature storage (−1.5°C), allow fresh pork to have a storage life long enough for export to overseas markets. During low-temperature storage of pork in these packaging systems, the lactic acid bacteria (LAB), which possess the enzymes for biogenic amine formation, dominate the microflora. The objectives of this study were to determine the quantities of biogenic amines in packaged fresh pork, to monitor LAB growth, and to determine the storage life by sensory evaluation. Vacuum-packaged and CO2-MAP pork were stored at −1.5 ± 0.5°C for 9 and 13 weeks, respectively. Phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine concentrations were determined weekly by high-performance liquid chromatography and capillary gel electrophoresis. LAB and carnobacteria were enumerated weekly. Samples were evaluated for odor and appearance. The CO2-MAP was successful in delaying bacterial growth and the development of unacceptable off-odors compared with the vacuum packaging. The storage lives of the vacuum-packaged and CO2-MAP pork were 5 and 13 weeks, respectively. High-performance liquid chromatography was the superior method for biogenic amine quantification. Tyramine and phenylethylamine in pork of both packaging treatments approached levels considered to be potentially toxic. Given Canada's increasing role in the export of fresh meat to foreign markets, it is recommended that the formation of biogenic amines in vacuum-packaged and CO2-MAP pork be further investigated.

The storage life of beef and pork packaged in an atmosphere with low carbon monoxide and high carbon dioxide

Ground beef, beef loin steaks and pork chops were packaged in modified atmospheres of 0.4% CO/60% CO 2/40% N 2 and 70% O 2/30% CO 2. In addition ground beef was packaged in clipped chub packs, beef loin steaks were vacuum packaged, and pork chops were packaged in an atmosphere of 60% CO 2/40% N 2 with each pack containing an O 2 absorber. The packs were stored in the dark at 4 or 8°C for up to 21 days. Meat in 0.4% CO/60% CO 2/40% N 2 had a stable bright red colour that lasted beyond the time of spoilage. The storage lives in this gas mixture at 4°C, as limited by off-odours, were 11, 14 and 21 days for ground beef, beef loin steaks and pork chops, respectively. The 70% O 2/30% CO 2 atmosphere resulted in an initially bright red to red colour of the meat, but the colour was unstable and off-odours developed rapidly. The off-odours probably were caused by Brochothrix thermosphacta, which grew in all meat types, or by pseudomonads in ground beef. Meat stored in chub packs, vacuum packs or 60% CO 2/40% N 2 with an O 2 absorber developed off-odours and microflora similar to those of meat in 0.4% CO/60% CO 2/40% N 2, but with less acceptable appearances. These results show that a low CO/high CO 2 atmosphere is effective for preserving retail-ready meat. ©

Observations on the survival of seeds of Agathis spp. stored at low moisture contents and temperatures

AbstractThree seedlots of Agathis australis (Lambert) Steud. (kauri pine) were stored hermetically at moisture contents of 1.5–15.5% and at temperatures from −20° to 42°C; and one seedlot of Agathis macrophylla was stored at 7%, 9% or 13% moisture content and at 26°, 6° or −13°C. Seeds of A. australis showed orthodox storage behaviour; except that viability was progressively reduced with drying below about 5% moisture content, and, depending on seedlot, subsequent storage longevities were reduced at all temperatures. Seeds of A. macrophylla again showed essentially orthodox characteristics at 9 and 13% moisture content; but drying to 7% moisture content reduced viability significantly, and of those seeds surviving, a further proportion died as a result of transfer to −13°C, and the remainder survived for 2500 d with little further viability loss. Seeds of neither species conformed fully to orthodox characterisics, nor to those of the intermediate category. The results are discussed in relation to possible causes of this ‘sub-orthodox’ behaviour, especially current seed-harvesting methods, and the limits put upon ex situ conservation of these species in seed banks by their predicted comparatively short storage lives.

Oxidative Stability of Sunflower and Olive Oils: Comparison between a Modified Active Oxygen Method and Long Term Storage

Shelf-lives of sunflower oil and olive oil were estimated using an Accelerated Shelf-life Testing (ASLT) method and these were compared with the values in long term storage. In addition, the effect of type, oxygen permeability, and transparency of the packages on the shelf-lives of oils were investigated. The determinations were based on the oxidative stability of oils by measuring their peroxide values. The limiting peroxide value corresponding to the end of shelf-life was obtained from the FAO/WHO standards. The shelf-lives of sunflower and olive oil samples in retail store conditions were estimated as 10.6 and 20.8 mo, respectively. Storage lives of sunflower oil in polyethylene tere-phthalate (PET), clear glass and colour glass bottles under a 10 W fluorescence lamp were 10.4, 11.1 and 11.8 mo at 10°C, and 4.8, 5.1 and 6.5 mo at 20°C, respectively. Long term storage lives of olive oil in PET, clear and coloured glass were 17.5, 17.8 and 18.3 mo at 10°C, and 8.0, 8.4 and 8.7 mo at 20°C, respectively. These long term storage lives were then compard with the ASLT results obtained from the modified active oxygen method using a simple shelf-life plot approach.

Storage lives of chilled and frozen fish and fish products

This Paper describes a meeting that was timely and clearly of wide international interest. It brought together people of diverse backgrounds — academics, Government research workers, inspectors, industrialists and others and, although no clear conclusions emerged, there was general agreement that the participants gained considerably from the information presented and discussed. It focussed attention on the areas where information is still lacking and hopefully it will have stimulated endeavours in one way or another to further our understanding of fish as food and thereby improve the quality available to the consumer.

Change in physicomechanical properties of certain constructional polyamides in natural aging

The life and reliability of polymer material parts are determinedto a large degree by their resistance to the action of atmospheric conditions. A study of the kinetics of natural aging of polymers in different climate zones and determination of the factors having the most negative influence on their service properties make it possible to scientifically establish the service and storage lives of polymer material parts.

ENERGY CONSUMPTION FOR REFRIGERATED, CANNED, AND FROZEN SNAP BEANS AND CORN

ABSTRACTThe energy inputs at different stages in the food cycle of corn and snap beans were estimated for refrigerated, canned, and frozen market forms. In the case of corn, the energy inputs totalled 3,146, 2,986, and 3,902 Btu/2.9 oz serving for canned, frozen, and refrigerated market forms. The corresponding figures (Btu/2.3 oz serving) for snap beans were 2,913, 2,715, and 2,134, respectively. The difference between the magnitudes for the canned and frozen forms is not significant. Further, because of the variability in the energy data for the different stages in the food cycle, magnitudes of energy consumption different than those listed may be obtained. The present and earlier studies on vegetables show that edible yield (number of servings) plays a major role in the energy consumed in the total cycle. Based on the present and previously published studies on energy consumption for vegetables, it appears that raw or refrigerated vegetables with yields more than about 40%will require less energy than other market forms. In this context, while most raw vegetables have yields higher than 40% they have short storage lives. Therefore, a large number of vegetables must be frozen or canned for long term availability.

Studies on the Effect of Antioxidants on the Stability of Sesame (<i>Sesame indicum</i> linn.) Seed Oil During Storage

The oil extracted from sesame seed kernel was stored in white plastic containers using different antioxidants like Butyl hydroxy anisole-BHA, Butyl hydroxy toluene-BHT and propyl gallate-PG at various percentages (0.01-0.05%) at room temperature for 12 months. The results were evaluated after 2- months in terms of free fatty acid (FFA), iodine value and peroxide value . It was observed that the rate of increase in free fatty acid (FFA), was appreciably lower in all the three oils stored with 0.02% BHA, BHT and PG than those of the oils containing other percentages of 0.01, 0.03,0.04 and 0.05 of antioxidants. Among these three oils of sesame (0.02%) percentages of antioxidants, the rate of increase in free fatty acid (FFA) of the oil containing 0.02% of BHA was found to be the lowest (0.1372). The iodine values of the oils were not influenced by any antioxidants of any percentages. But the rate of increase in peroxide value of the oil containing 0.02% of BHA was also found to be significantly lower. Most significant differences in storage lives was observed in the stored oil containing 0.02% of BHA. Key words: Antioxidant, Free fatty acid, Iodine value, Peroxide value. Storage life, Fat-oxidant. DOI: 10.3329/bjsir.v43i2.967 Bangladesh J. Sci. Ind. Res. 43(2), 235-242, 2008

Studies on the storage of fruits and vegetables. II

This study was undertaken to find the best method of lengthening the storage life of horticultural products by the use of packaging with plastics bags.Experiments were conducted to examine the effects of the weight difference of products in each bag, of the type and thickness of plastics film, and of the replacement of air in bags with inert gases (N2, CO2) at the time of sealing on the composition of atmosphere in the bag during the storage.Pea in pod, kendey bean, lettuce and bell pepper were used in this experiments. The results were as follows; Polyethylene and polystyrene bags were more beneficial to get desirable gas-conditions in bags than polyvinyl chrolide, polypropylene and polyester bags. The film of 0.03-0.05mm thickness, containing proper amount of products, were suitable to prolong storage lives; CO2 and O2 concentrations of atmosphere in the bags were maintained stably since a few days after sealing.Introduction of N2 gas into the bags brought about good CA-conditions in bags immediately, and the storage-lives of the products were extendend more than that of conventional package.

Extension of storage lives of potatoes and onions by cobalt-6o π-rays

Phulwa potatoes and Red Globe onions were irradiated with 6 krad of CoF of 3 krad/min and stored with controls at two temperatures, viz. room temperature (21–35°C; R.H., 57–90 per cent) and cold storage (11–12°C; R.H., 85–90 per cent). The dose employed was sufficient to prevent the sprouting of potatoes and onions at both the temperatures. Decay started earlier in the irradiated potatoes as compared to the controls at room temperature. However, there was no decay in control or irradiated potatoes in cold storage. It appears that irradiation does not destroy part of the reduced ascorbic acid but changes it to the dehydro form which is re-converted to the reduced form on boiling the potatoes. There were no adverse effects on colour, texture, taste or flavour in boiled irradiated potatoes after 10 months of cold storage. There was no difference in the extent of waste due to disease between the control and irradiated onions at room temperature. In cold storage, however, no decay occurred in either of the two lots of onions. There was no reduction in the reduced ascorbic acid content of onions after irradiation. Raw irradiated onions were slightly sweeter and less pungent after 8 months of cold storage, there being no adverse effects on colour and texture.

Storage of Mandarin Oranges II. Effects of Hormones and Wax Coatings

SUMMARYThe effects of temperature, wax emulsion coating, hormone treatment, and their combination on the storage behavior of Nagpur and Darjeeling mandarins were investigated. Use of 2,4‐D with wax coating was more effective in prolonging the storage life of both varieties at any storage temperature than either wax coating or 2,4‐D used separately. The storage lives of Nagpur and Darjeeling oranges were respectively 50 and 35 days at normal temperature (50–85°F) and 90 and 75 days at 40 ± 1°F when treated with 2,4‐D (1000 ppm for Nagpur and 2000 ppm for Darjeeling varieties) followed by wax coating. Wax‐coated Nagpur and Darjeeling oranges were in a good marketable condition for 30 and 22 days, respectively, at room temperature, whereas the respective controls remained marketable for only 10 and 7 days. At 40 ± 1°F, storage lives were respectively 60 and 52 days for Nagpur and Darjeeling oranges coated with wax, and 40 and 25 days for their respective controls. Hormone‐treated fruits, like the controls, lost their marketable appearance through considerable desiccation, pitting, and shriveling. Loss in weight and spoilage due to fungal attack and rind blemishes were least in fruits treated with 2,4‐D followed by wax coating in both varieties and each storage temperature. Pulp‐to‐peel ratio, reducing sugar, sucrose, total sugar, sugar‐to‐acid ratio, pH value, and specific gravity in juice increased, whereas vitamin C content and titratable acidity decreased, during storage in all treatments. No off flavor was produced in any case.

煉製品に適用した食品防腐剤の混用効果

The production of fish cakes in Kagawa Prefecture has been supported in respect of the raw material almost exclusively by fishes caught by trawling on the Northeastern China Sea. Therefore, the manufacturers concerned are usually obliged to use a raw fish rather degraded in freshness, which is necessarily apt to result in a short keeping of the product especially in summer. Their occasional use of boric acid and the like as the last resort for elongating the storage life of their elaborations gets often into trouble, because our food sanitation law prohibits the use of said chemicals as a preservative of food. To save these difficulties, the authors examined the availability of sorbic acid, nitrofurazone and nitrofurylacrylamide for protecting fish cakes from readily undergoing putrefaction. Organoleptic and bacteriological examinations made on three types of fish cake which had been prepared from batches of raw flesh added with said chemicals, either separately or in combination, and exposed after their preparation to temperatures between 25.5° and 32.2°C and relative humidities between 80 and 91% presented the following results: 1. Preservabilities of Tempura and Chikuwa can be little improved by the presence of 1% soribic acid together with N.F. (a mixture containing 3-(5-nitrofuryl) acrylamide and nitrofurazone in a ratio of 4: 1) at an amount less than 0.0005%. But the storage lives of these fish cakes can be distinctly lengthened by the presence of 0.001-0.002% N. F. added to raw flesh, and it is further elongated by additional presence of 1% sorbic acid even to such an extent as unattainable by singular uses of these chemicals at said concentrations. 2. When applied to Kamaboko, N. F. exhibits a preservative effect which lasts over 40 hours to be almost 40 times as strong as that of sorbic acid. 3. Singular application of N.F. at concentrations lower than 0.002% brings about no favorable effect on the preservation of Tempura and Chikuwa.

Effect of storage on the chemical composition of husked, undermilled and milled rice

AbstractRaw husked rice, raw undermilled rice containing I‐8 μg. of thiamine/g., parboiled rice and raw milled rice were stored in gunny bags for a period of one year. The samples were kept free from infestation. The changes in the grain during storage have been studied. The amylase activity in freshly harvested rice decreased rapidly; there was an improvement in the cooking quality, and in all the samples, except parboiled undermilled rice, a loss of thiamine of about 20‐30% was observed. A decrease in nitrogen soluble in 3% sodium chloride solution was observed, and this may be due to denaturation of protein during storage. There was an increase in the acidity and the peroxide value of the fat present in the different samples of rice, the increase being at a maximum for husked rice. The storage lives for the various samples, as estimated by plotting the peroxide values of the fat against the storage period for all the samples in conjunction with organoleptic tests at the end of one year, are approximately as follows: raw husked rice, 7 months; raw undermilled rice, 12 months; parboiled undermilled rice, II months; and raw milled rice 13 months.