气调包装技术用于草虾保鲜的研究

介绍了将气调包装技术 (modifiedatmospherepackaging)用于草虾保鲜。将虾浸泡在10 0mg/L溶菌酶和 1.2 5%亚硫酸氢钠的保鲜液中处理之后 ,采用 4 0 %的CO2 和 6 0 %的N2混合气体灌充尼龙 /聚乙烯塑料袋进行包装 ,2～ 4℃保藏 ,其保质期较对照样品延长了 2 2d ,是对照样保质期的 6 .5倍。通过菌落计数 (APC)和总挥发性碱基氮 (TVB N)的分析方法 ,监测虾样品的微生物及化学变化 ,并进行了感官评价     

Investigation of colour changes of some tomato products during frozen storage

The colour changes of frozen tomato pulp were investigated under different conditions of frozen storage (?25°C; in open bags with presence of O₂ and in artificial light or darkness; in closed bags also in artificial light or darkness). In addition the antioxidative effect of tomato seeds and spices (sage, thyme, rosemary, oregano, majoram) was studied. The colour change of tomato pulp was determined with instrumental colour measurement, the carotenoid pigments loss was measured with UV/VIS spectrophotometry. It was found that exposure to light and oxygen accelerated the colour loss and oppositely packaging and storage in darkness had a colour saving effect. The ground tomato seeds (5%) could stabilize the carotenoid pigments after longer time frozen storage (min. 10 weeks). The commercial spices (0.2%), mainly rosemary and marjoram significantly reduced the pigment degradation. The tomato seeds and the spices did not change significantly the taste of tomato pulp.     

Cis-trans isomerisation of lycopene and colour stability of foam—mat dried tomato powder during storage

Tomato powder with ～3% moisture was obtained by foam-mat drying tomato paste (29% solids). Samples of powder were stored at various temperatures (?10° +2° +20° and +37°c), atmospheres (air, nitrogen) and humidities (with and without in-package desiccation), and colour changes were observed for periods of up to 1 year. The main cause of colour fading was the oxidation of lycopene. However, another phenomenon, trans—cis isomerisation of all-trans lycopene, can occur, with apparent loss of coloration, which is later restored by re-isomerisation. The existence of this mechanism was demonstrated by simultaneous measurements of total liposoluble colour at 420 nm and separations of carotenoid pigments by column chromatography on Al₂O₃. Neo-lycopene A (6-mono-cis-lycopene) and at least one other cis-lycopene isomer were found in fresh powder and in samples stored up to 5 months. cis-Isomers were more susceptible to oxidation. Colour changes depend upon the interplay of isomerisation and oxidation; in some cases, tomato powder was more intensively coloured after storage than when fresh. Storage at +20°c was more favourable for colour retention than storage at +2°c, or — 10°c. Excessive desiccation strongly promoted oxidation losses. Storage in an inert atmosphere improved colour retention. At +37°c non-enzymic browning, accompanied by formation of water, caused rapid darkening although carotenoid pigments were not lost to a great extent.     

Lipid Oxidation and Sensory Analysis of Cooked Pork and Turkey Stored under Modified Atmospheres

Precooked pork and turkey were stored at 4°C for 18 hr and at - 20°C for 3 months in vacuum and in atmospheres of air, carbon dioxide, and nitrogen. For both short-term refrigerated storage and long-term frozen storage, vacuum-packaging of precooked turkey and pork resulted in more meaty and less warmed-over flavor and aroma than the other packaging treatments. Samples stored in carbon dioxide and nitrogen atmospheres were less “oxidized” as indicated by sensory scores and TBA values than those stored in air but were more “oxidized” than vacuum-packaged meat. Warmed-over and rancid flavor and aroma scores correlated highly and consistently with TBA values, but inconsistently with the less sensitive fluorescence method. Vacuum-packaged turkey was darker and redder than other samples after frozen storage.     

QUALITY OF MODIFIED ATMOSPHERE PACKAGED "BARTLETT" PEARS AS INFLUENCED BY TIME AND TYPE OF STORAGE

Commercially mature “Bartlett” pears for this study were obtained from local commercial packing facilities. In the first year, pears were packed in modified atmosphere bags and placed in boxes or packed normally (control) with an individual paper wrap around each pear plus a polyethylene liner in the box. Boxed pears from both types of packaging were stored in regular atmosphere (RA) storage at 1C for 30 or 90 days. In the second year, pears were packed normally and stored in both RA or controlled atmosphere (CA) storage for 45 or 90 days, or packed in modified atmosphere bags and stored in RA at 1C. After 45 days, normally packed pears from both RA and CA were removed from their initial storage, placed in modified atmosphere bags and returned to RA storage for an additional 45 days. Pears stored in modified atmosphere bags were superior in quality to normally packed pears stored only in RA storage and equal in quality to pears stored in CA for periods of 90 days. The quality of pears held in modified atmosphere bags under CA conditions deteriorated after only short periods of time (<45 days). Pears in modified atmosphere bags should be stored only in RA. Little or no quality advantage was evident if use of modified atmosphere bags was delayed regardless of prior storage type.     

Effect of freezing/thawing conditions and long‐term frozen storage on the quality of mashed potatoes

The effects of freezing temperature (−80, −40 or −24 °C) and thawing mode (microwave or overnight at 4 °C) on quality parameters of mashed potatoes made from tubers (cv Kennebec) and from potato flakes were examined, as was the effect of long‐term frozen storage on the quality of mashed potatoes. Mashed potatoes were tested for texture profile analysis (TPA) and cone penetration, oscillatory and steady rheometry, colour, dry matter, Brix and sensory analyses. In natural mashed potatoes, TPA hardness and oscillatory parameters showed that processing resulted in a softer product than the fresh control. The parameters were lower in the samples thawed at 4 °C than in those thawed by microwave at all the freezing temperatures used, which may be ascribed to gelatinisation of the starch released from damaged cells. Differences from the freshly prepared product decreased when the samples were frozen at −80 °C and thawed by microwave. No difference was found in sensory acceptability between samples frozen at −80 and −40 °C, which probably reflects the panellists' mixed preferences for air‐thawed versus microwave‐thawed samples. Increasing the time in frozen storage led to a natural mash with a firmer texture, higher L*/b* value and Brix; nonetheless, panellists found the samples at 0, 3 and 12 months of frozen storage equally acceptable. In commercial mash, penetration and oscillatory parameters showed that processing made for a firmer product than the fresh control, probably owing to retrogradation of gelatinised starch. Thawing mode had a significant effect on parameters, which were lower in the samples thawed at 4 °C. The structure and quality of commercial mash was more detrimentally affected by freezing and, therefore, we would not recommend either freezing or frozen storage of this mashed potato in the used conditions. Natural mash made from Kennebec potatoes should be frozen quickly and thawed by microwave in the conditions described to obtain a product more similar to that freshly made. If the samples are frozen by air blasting at −40 °C, the product can withstand frozen storage for one year. Copyright © 2005 Society of Chemical Industry     

Changes in texture,microstructure and nutritional quality of carrot slices during blanching and freezing

Thermal processing of vegetables has pronounced effects on the cell structure, often lowering the final textural properties of the product. In order to investigate the effect of thermal processing on carrot, slices were subjected to different blanching and freezing treatments before frozen storage. Microwave-, steam- or water-blanched material was frozen and then stored at −24 °C. Steam-blanched carrots were subjected to blast freezing or cryogenic freezing at different temperatures before frozen storage. The influence of these process conditions on the texture (maximum load and slope), microstructure, dry matter, sugars, carotene and drip loss was investigated. Microwave blanching differed from the other blanching methods by resulting in a heterogenic cell structure. The content of dry matter, carotene and sucrose was higher following microwave blanching. Blast freezing resulted in low maximum load which seemed to be caused by major tissue damage. Concerning cryogenic freezing, lowering the temperature from −30 °C to −70 °C resulted in better preservation of the native microstructure together with an increase in maximum load, which was most pronounced after one month of storage. No significant effect was observed when lowering the temperature from −30 °C to −70 °C for any of the other measured parameters. © 1999 Society of Chemical Industry     

Improved keeping quality of minimally fresh processed celery sticks by modified atmosphere packaging

Recommended storage conditions of green celery sticks are 4 °C for 10 days, but there are no reports about optimal modified atmosphere packaging (MAP) conditions to preserve them longer. The objective of this research was to describe the gas composition of MAP generated by two polymeric films and its effects on chemical, sensorial and microbial quality, and physiological disorders of celery sticks stored at 4 °C for 15 days. Green sticks of 15-cm length of ‘Trinova’ cv. were placed in hermetically sealed plastic bags: low-density polyethylene, oriented polypropylene (OPP) and polyethylene-perforated bags as control (air). The O₂ and CO₂ concentrations, soluble solid content, pH, titratable acidity, colour, sensorial quality and sugar and organic acids contents were monitored. Compared to the control, both MAP treatments improved the sensory quality, avoided the loss of green colour, decreased the development of pithiness and retarded the growth of microorganisms. In any treatment neither off-odours nor off-flavours were detected. After 15 days at 4 °C within the OPP bags a steady-state atmosphere of 6 kPa O₂+7 kPa CO₂ was reached and celery sticks stored under these bags showed the best quality.     

Drip loss,peroxidase and sensory changes in kiwi fruit slices during frozen storage

The biochemical, sensory and drip loss changes that occur during processing and prolonged frozen storage of kiwi fruit slices (cvs Abbott and Hayward) were studied. Fruit slices were frozen at ?40°C, packed in polyethylene bags and stored at ?18°C for 11 months. Maturity characteristics (pH, acidity, dry matter, soluble solids) were determined on raw fruit. Objective (proteins, peroxidase (EC 1.11.1.7) activity, drip loss) and subjective (sensory tests) analyses were carried out during processing and storage, and indicated a good quality of the frozen kiwi fruit slices after 11 months of storage. There were significant differences (P < 0.05) between the studied varieties with respect to drip loss during frozen storage and colour after 11 months. Best results were obtained with cv Hayward. This variety showed less drip loss after thawing and after 11 months storage presented the same green colour as after freezing, while cv Abbott became yellowish-green.     

Influence of Storage Atmosphere on Several Chemical Parameters of Sun-Dried Shrimp

Sun-dried shrimp from Taiwan and Louisiana were stored at 22°C for 8 months in modified atmospheres of air or vacuum. Packages were randomly selected at 2-month intervals and analyzed for moisture, water activity (a_w), total volatile nitrogen, ammonia and pigment oxidation. Moisture and a_w were shown to decrease during the storage period regardless of the package atmosphere; however, the amount of decrease was less in samples stored under vacuum than in air. Total volatile nitrogen and ammonia increased during the storage period, with samples stored in air showing the greatest increases. Pigment oxidation reached a maximum at 4 months, samples stored in a vacuum showed the least amount of oxidation.     

Quality Changes in Unsulfured Sun Dried Apricots During Storage

The sun dried apricots (Hacihaliloglu) from Malatya region of Turkey without sulfur dioxide application packaged in polyvinyl chloride laminated with polyethylene bags of different thickness under normal and modified atmosphere were stored at 5 ± 1, 15 ± 1, and 25 ± 1°C, respectively. The changes in quality characteristics of dried apricots were investigated by using objective and sensory methods of evaluation during a storage period of 48 weeks. The study showed that the unsulfured sun dried apricots have a storage life of up to 30 weeks provided that they are packaged under modified atmosphere and stored at 5 ± 1°C after processing.     

不同气调包装袋对红心猕猴桃后熟品质的影响

目的 为探究不同的气调包装对红心猕猴桃的保鲜效果。方法 采用两种不同类型自发气调包装袋包装红心猕猴桃,以市售微孔包装包装袋作对照,研究低温（5±1°C）贮藏时,不同气调包装袋包装的红心猕猴桃的生理特性及营养成分的变化规律。结果 与市售微孔包装袋相比,气调包装袋能够在猕猴桃后熟期间控制氧气含量低于10%,二氧化碳含量不高于5%,使其充分后熟的同时有效延缓呼吸高峰的出现,降低呼吸高峰,有利于猕猴桃的品质保持和营养成分积累。结论 贮藏30天以上时,MP20袋内低氧低二氧化碳的气体环境有利于红心猕猴桃的贮藏,品质和营养成分含量明显优于市售微孔袋,MP20气调包装用于保鲜红心猕猴桃具有较好的市场应有前景。     

Effect of storage conditions on the quality of smoke-dried herring (Sardinella eba)

Samples of freshly smoked herring (Sardinella eba) at 140 g kg^?1 moisture were stored for a maximum period of 6 months using five different storage methods: in polyethylene bags at ambient temperature with and without desiccant, frozen ( ?20°), as well as the traditional and a modified oven storage technique. Their relative effectiveness in preserving the quality of the fish was evaluated in terms of storage losses, sensory changes and decomposition. Next to frozen storage, the most effective method was the modified procedure which gave storage yields of 97% and high sensory scores. Proteolytic and lipolytic deterioration was negligible. Although the traditional storage retained high sensory and chemical properties, over 30% storage losses were recorded. Storage in polyethylene bags at ambient temperature was ineffective, while inclusion of desiccant only delayed total decomposition beyond one month. Major organisms observed in stored smoked herring were Micrococcus, Bacillus, coryneform group, Aspergillus, Penicillium, Rhizopus and yeasts.     

Corn Starch-Xanthan Gum Interaction and Its Effect on the Stability During Storage of Frozen Gelatinized Suspension

The knowledge of starch pastes behavior during frozen storage becomes necessary to understand more complex systems (e.g. sauces, dressings and desserts) The effect of sub-zero storage on the quality attributes of corn starch pastes (10% w/w) with and without xanthan gum (0.3% w/w) was analyzed. Pastes were frozen at different rates (0.3 to 270cm/h) and stored at −5, −10 and −20°C. Exudate production (syneresis) and rheological behavior were studied by means of capillary suction and rotational viscometry respectively. Ice recrystallization was analyzed by indirect microscopic observations using isothermal freeze fixation and amylopectin retrogradation by differential scanning calorimetry (DSC). Samples stored at −5°C (glass transition temperature) or higher temperatures were under the rubbery state evidenced by starch recrystallization. This state favored molecular mobility leading to deteriorative changes (like spongy structure formation related to amylose retrogradation). At lower storage temperatures (−10 and −20°C) under the glassy state, starch retrogradation was not detected and deteriorative changes can be related to ice recrystallization. The addition of xanthan gum minimized amylose retrogradation, syneresis and rheological changes, however, its presence did not prevent ice recrystallization nor amylopectin retrogradation.     

Optimizing storage temperature of liquid bovine semen diluted in INRA96

Temperature regulation of liquid bovine semen can be difficult in field situations. Two experiments were carried out to assess the effect of storage temperature on in vitro sperm characteristics and 60-d nonreturn rate (NRR) following artificial insemination (AI) of liquid bovine semen. In experiment 1, the effect of storage of liquid bovine semen in INRA96 diluent (IMV Technologies, L'Aigle, France) at 1 of 5 storage temperatures (5, 15, or 28°C, and fluctuating between 5 and 15°C or 5 and 28°C) on total and progressive motility and kinematic parameters was assessed objectively via computer-assisted sperm analyzer on d 0, 1, 2, 3, and 4 after collection. Fluctuating temperatures were designed to mimic day- to nighttime variation. In experiment 2, we assessed the field fertility of liquid semen stored at a constant 5 or 15°C or in an unregulated manner and compared with that of frozen-thawed semen (total of n = 106,738 inseminations). In experiment 1, we detected a linear decrease in motility with increased duration of storage. Semen stored at a constant 15°C or fluctuating between 5 and 15°C had greater total motility than semen held at 5 or 28°C or fluctuating between 5 and 28°C; however, semen stored at 15°C and fluctuating between 5 and 15°C did not differ from each other. Semen held at a constant 5 or 15°C or fluctuating between 5 and 15°C, although not differing from each other, had higher progressive motility scores than that held at 28°C or fluctuating between 5 and 28°C. Semen stored at a constant 28°C exhibited poor motility and velocity values but had high progressive motion values compared with that all other storage temperatures; however, the other storage temperatures did not differ from each other in relation to motility kinematics. In experiment 2, semen stored at a constant 5°C resulted in a lower 60-d NRR (62.5%) than storage at constant 15°C or unregulated temperature or frozen-thawed semen (73.6, 74.6, and 74.4%, respectively. In conclusion, sperm stored in IRNA96 are quite tolerant in terms of storage temperature, retaining acceptable motility between 5 and 15°C. Storing semen at a constant 15°C resulted in greater in vitro sperm motility and higher NRR rates than storage at 5°C and did not differ in NRR from frozen-thawed semen or semen stored at an unregulated temperature; however, lower storage temperatures were shown to be more detrimental to sperm in vivo than unregulated storage conditions.     

Effect of Carbon Dioxide Modified Atmosphere on the Compressibility of Stored Baked Goods

Whole wheat flour breads, white breads and biscuits were stored in flexible packages flushed with either air, 100% nitrogen or 100% carbon dioxide. Compressibility tests were performed during a storage time of 13 - 15 days for bread and 7 - 15 days for biscuits. Significantly lower regression coefficients (P < 0.01) were found for white and whole wheat breads and biscuits stored in carbon dioxide modified atmosphere than for the air stored samples. No significant differences were found between regression coefficients of air and nitrogen stored bread samples. Mold growth was inhibited on breads and biscuits by carbon dioxide atmosphere during 13 - 15 days of storage, but occured between the 5th and 7th day of storage on the air packaged samples.     

Shelf Life of Sunflower Kernels

One raw and two oil roasted samples of sunflower kernels packaged in paper bags and in two types of low oxygen atmosphere pouches were stored at 5, 21 and 38°C. Quality of the stored samples was monitored by an expert sensory panel, peroxide, hexanal, free fatty acids and moisture determinations. Liking ratings, obtained with 99 consumers after 24 wk storage, were used to select end points for expert sensory ratings. The shelf life for roasted sunflower kernels was greater than 12 month when stored in nitrogen flushed pouches and as low as 8 wks when exposed to air at 38°C. Hexanal was a better index for shelf life of roasted sunflower kernels than was peroxide. The shelf life of raw sunflower kernels was > 12 month in packages providing some moisture but no oxygen protection.     

Effects of frozen storage temperature on the quality and oxidative stability of bigeye tuna flesh after light salting

Effects of frozen storage temperature on the quality and oxidative stability of lightly salted tuna were investigated. The bright and vivid colour became totally brown after 4 weeks at −20 °C and 8 weeks at −30 °C, where the a^*/b^* value decreased from 1.35 to 0.38 and 0.58, respectively. Discoloration and lipid oxidation occurred concurrently in lightly salted tuna flesh, and it was speculated that the oxidation of oxymyoglobin to metmyoglobin exacerbated lipid oxidation and vice versa. Storage at −40 °C or lower temperatures effectively suppressed the discoloration and maintained the high water-holding capacity and unique textural properties of lightly salted flesh. It was attributed to the reduction in the conformational changes and particularly hydrophobic interactions among proteins, protecting the myoglobin from oxidative damages during frozen storage. Considering the quality maintenance and energy savings, storage at −40 °C was appropriate for lightly salted tuna flesh.     

南美白对虾冰温气调保鲜效果评价

将鲜南美白对虾进行空气包装(AP)、真空包装(VP)、气调包装(MAP,75% CO2/25% N2),分别冰温(－2.3～0℃)贮藏和冰藏,通过研究样品贮藏过程中多酚氧化酶(PPO)活力、总挥发性盐基氮(TVB-N)、菌落总数(TPC)、汁液流失率(DL)的变化,结合感官指标评价冰温气调保鲜的效果。结果表明：南美白对虾的PPO活力变化与腐败变质同步;冰温结合MAP能有效防止褐变,货架期可达10d,比冰藏结合AP延长了约3倍,此时样品色泽良好,TPC、TVB-N、DL分别为5.4(lg(CFU/g))、25.6mg/100g、3.13%,而其他包装样品已腐败。VP也能较好的保持色泽,但贮藏后期汁液流失相对严重,影响外观。     

Sensory and microbiological quality of shiitake mushrooms in modified‐atmosphere packages

The aim of the present work was to study the influence of modified‐atmosphere packaging on the microbiological and sensory quality of shiitake mushrooms (Lentinula edodes). Mushrooms were packaged under atmospheric air (passive modified atmosphere) and an initial gas mixture of 5% O₂ and 2.5% CO₂ (active modified atmosphere), in bags of two different films: low‐density polyethylene (PE) and polypropylene (PP). As control, mushrooms were packaged in macroperforated PP films. Bags were stored at 5 °C for 20 days. Package atmosphere composition, mushroom respiration rate, weight loss, microbiological counts and sensory quality were determined during storage. Risk assays were also performed. Under the studied conditions, shiitake mushroom deterioration was not due to microorganism growth, and therefore the shelf‐life of this product might be defined by changes in its sensory characteristics. Sensory analysis showed that mushrooms stored under modified atmosphere (active and passive) had a higher deterioration rate than those stored in PP macroperforated films, and lower sensory quality values during the entire storage time. These results suggest that mushroom deterioration was probably due to shiitake mushrooms' sensitivity to high CO₂ concentrations. Copyright © 2007 Society of Chemical Industry