Effect of Storage Temperature and Time on the Quality of Vacuum Packaged Dry-Cured Ham Slices

Hams were cured and aged by three methods, two using nitrite and nitrate but with long or short aging times at controlled temperature, and one using no nitrite or nitrate with ambient aging temperature. Hams were sliced, vacuum-packaged and stored at 0°C, 10°C or 21°C for 8 wk and examined weekly for white film, aroma, and aerobic, staphylococci, lactobacilli, yeast and mold counts. White film development was erratic. Aroma was closely related to aerobic counts. At 0°C bacterial counts and aroma remained normal for 8 wk. At 10°C many packages had acceptable counts and aroma at 8 wk but some were unacceptable by 4 or 5 wk. At 21°C many slices were unacceptable microbiologically and sensorily by 3 wk. Storage at or near 0°C is recommended for long shelf life.     

Effects of Gas Atmosphere, Storage Temperature and Storage Time on the Shelflife and Sensory Attributes of Vacuum Packaged Ground Beef Patties

The effects of modified atmosphere packaging systems on the shelflife and palatability attributes of ground beef patties were determined. Packaging systems evaluated were 100% nitrogen backflush, 100% carbon dioxide backflush and no gas backflush (no oxygen). Vacuum-packaged samples were stored at 0, 4 and 8°C for 7, 14, and 21 days. Percent purge increased as storage temperature increased and as time in storage increased (up to 14 days of storage). Nitrogen backflush produced the lowest purge values; vacuum packaged controls had the highest levels. Kramer shear values and microbial counts increased with time in storage. Sensory traits indicated that the carbon dioxide treatment yielded higher taste panel scores. Sensory panel values decreased with time in storage.     

Study of the White Film Developed on the Cut Surface of Vacuum-packed Dry-cured Ham Slices

Scanning electron microscopy of the white film developed on the cut surface of some vacuum-packed dry-cured ham slices showed a fibrous structure composed of protein materials. Gradient SDS-PAGE revealed the main components in the film were proteins with molecular weight in the range 26000–87000, but especially 37000, 41000, 56000, and 65000. Free amino acids were also in the film in low proportions (250 μg total free amino acids per mg of protein). The main amino acids were proline methionine, isoleucine, leucine, phenylalanine, histidine and tyrosine. 11.7% of the total free amino acids was tyrosine, thus indicating its minor role in formation of white film.     

复合精油涂层对干腌火腿抑菌及抗氧化作用的影响

以猪油和淀粉为抗氧化涂层基料、山苍子精油和肉桂精油为抑菌及抗氧化剂制备涂层材料,通过单因素试验和正交试验研究不同山苍子精油和肉桂精油配比、复合精油添加量和强化高温成熟温度对火腿半膜肌的抗氧化及抑菌作用。结果表明:当山苍子精油和肉桂精油配比为1∶0.5~1∶2(m/m)、复合精油添加量为0.03%~0.05%(以涂层基料总质量计)时,复合精油涂层对火腿半膜肌的脂质氧化、菌落总数及霉菌数均有较好的抑制作用;在山苍子精油和肉桂精油配比为1∶1、复合精油添加量为0.05%、强化高温成熟温度为35℃的最佳工艺条件下,火腿半膜肌的硫代巴比妥酸反应物质(thiobarbituric acid reactive substances,TBARs)值为0.549 mg MDA/kg、霉菌数为1.341(lg(CFU/g))、菌落总数为3.662(lg(CFU/g)),与未涂层组相比分别降低了24.0%、43.4%和31.1%。可见复合精油涂层能显著降低火腿半膜肌的脂质氧化程度、抑制微生物的生长。     

Effect of Time, Temperature, and Slicing on Respiration Rate of Mushrooms

ABSTRACT:  Respiration rate measurement considering the effects of cutting, temperature, and storage time are important for the shelf life study and modified atmosphere-packaging design of fresh-cut produce. This study investigates in the respiration rate of fresh whole and sliced mushrooms at 0, 4, 8, 12, 16, and 20 °C under ambient atmosphere and different storage times. The O₂ consumption rate increased with temperature and ranged from 22.13 to 102.41 mL/(kg.h) and 28.87 to 143.22 mL/(kg.h) for whole and sliced mushrooms, respectively, in the temperature range tested. Similar trend was observed for CO₂ production rate. Slicing of mushrooms increased the respiration rate by 30% at 0 °C and 40% at 20 °C indicating that the mushrooms are not as sensitive to the stress caused by cutting as other fresh produce. Storage time affected both respiration rate of whole and sliced mushrooms and this effect was prominent at higher temperatures. The respiration rates increased initially for some time, then decreased and reached steady state value at 12, 16, and 20 °C. A 2nd-order polynomial equation was used to fit the respiration rate data as a function of time at each temperature tested.     

Effects of Temperature During the Last Month of Ageing and of Salting Time on Dry-Cured Ham Aged for Six Months

In Spanish dry-cured ham the temperature is sometimes increased at a specific stage in order to accelerate the ageing process. In this study the effect of temperature during the final month of a 6-month process on certain physicochemical and sensorial characteristics of hams cured for different salting times was evaluated. Three salting times and three different temperatures (20, 25 and 30°C) during the last month of the process were used. Whole ham weight losses and the incidence of white film and tyrosine crystals on the cut surface were evaluated; and chemical and sensory analysis were carried out on Biceps femoris muscle. Despite reducing white film and tyrosine crystals, an increase of 2 days in salting time, had a slight effect on texture and produced an increase in the salty taste which could be regarded as excessive. Tyrosine concentration, the incidence of white film, brightness, pastiness and piquantness, all of which may negatively affect consumer acceptability, were greater in the hams with 30°C ageing temperature. © 1997 SCI.     

Physical and Sensory Characteristics of Vacuum Packaged Beef Round Steaks as Influenced by Postmortem Age and Storage Temperature

Two steaks were removed from the semitendinosus, semimembranosus and biceps femoris muscles at 3, 6 or 9 days postmortem and vacuum packaged. Steaks were stored for 48 hr at 2°C or 7°C before retail display. Steaks cut at 3 days had less (P < 0.05) surface discoloration than those removed at 6 or 9 days. In most comparisons, steaks removed at 3 days were more desirable (P < 0.05) in overall appearance than steaks removed at either 6 or 9 days and stored at either temperature. Storage temperature did not accelerate lean color development for vacuum packaged beef round steaks. With increasing time postmortem before fabrication into steaks, longer storage periods may be needed before display to allow devet opment of proper lean color.     

Development of Staphylococcal Toxin and Sensory Deterioration During Storage of Nitrogen and Vacuum Packaged Nitrite-Free Bacon-Like Product

Toxin production by S. aureus was studied in nitrite-free bacon-like product packaged in air permeable film, vacuum packages, and packages flushed with N₂ during storage at 8°C, 12°C or 26°C. Product wrapped in air permeable film deteriorated rapidly at 26°C and was rejected by sensory evaluation prior to staphylococcal enterotoxin detection. Enterotoxin was not detected in vacuum or N₂-flushed packages stored at 26°C. Samples stored at 12°C supported S. aureus growth although enterotoxin was not detected at 12°C or 8°C in any packaging environment. The potential for staphylococcal food poisoning resulting from the production of a nitrite-free bacon-like product was limited under the conditions studied.     

Development of Botulinal Toxin and Sensory Deterioration During Storage of Vacuum and Modified Atmosphere Packaged Fish Fillets

Toxin production by C. botulinum type E was studied in cod, whiting, and flounder filets packaged in air-permeable film, vacuum packages and packages flushed with N₂ or CO₂ during storage at 8°, 12° or 26°C. Cod and whiting filets were flushed with CO₂ and stored continuously at 4°C or cycled between 4° or 8° and 26°C. Cod and whiting fillets were flushed with gas mixtures and stored at 8°C or 26°C. Flounder deteriorated rapidly and was rejected by sensory evaluation prior to toxin detection during vacuum or modified atmosphere storage at 12°C and 8°C but after toxin detection at 26°C. Toxin was present either prior to or simultaneously with sensory rejection of cod and whiting fillets for all vacuum or modified atmosphere treatments and temperature regimens.     

Effects of Boning Time, Mechanical Tenderization and Partial Replacement of Sodium Chloride on the Quality and Microflora of Boneless Dry-Cured Ham

SEVENTY-TWO HAMS were utilized to study the effects of KCl replacement level (100:0, 70:30, 50:50 ratios of NaCl and KCl), boning time and mechanical tenderization on the quality and microflora of boneless dry-cured hams. Boning time had no effect on palatability or final yield. Hotboned hames had higher levels of residual nitrite and slightly higher microbial counts. Mechanical tenderization improved tenderness and microbial quality. However, tenderized hams had lower flavor preference and overall satisfaction scores. The replacement of NaCl with KCl at a level of 30% had no effect on palatability or microbial quality. NaCl replacement at a level of 50% severely decreased palatability and increased microbial numbers.     

Physical, Sensory and Microbiological Characteristics of Lamb Retail Cuts Vacuum Packaged in High Oxygen-Barrier Film

Lamb chops and steaks from fresh (F) or vacuum packaged (VP) racks, loins and legs were packaged in polyvinyl chloride (PVC) film or vacuum packaged in high oxygen-barrier (HOB) film. Use of previously vacuum packaged (PVP) cuts did not affect overall appearance of rib or loin chops during subsequent retail display but HOB film-packaged leg steaks from PVP cuts had lower overall appearance scores than did leg steaks from F cuts. Prior VP storage negatively affected flavor desirability and odor at the conclusion of retail display (4 days in PVC or 10 or 15 days in HOB film). Pseudomonas spp. were a dominant part of the microflora of PVC-wrapped chops while L. cellobiosus was a dominant part of the microflora of HOB-wrapped chops.     

Hot-Boning, Elevated Temperature Conditioning, and Vacuum Packaged Aging Influences on Lamb Cooking Losses and Palatability

Wether lambs (64) were utilized to examine the effects of hot-boning (HB), elevated temperature conditioning (ETC) and vacuum packaged aging (VPS) on the cooking properties and palatability attributes of racks. Samples were HB at approximately 45 min post-mortem and ETC for 0, 2, 4, or 6 hr at 32°C. Following ETC, samples were VPS for 6, 13, 27, or 41 days at 1–2°C. Wholesale racks could be HB at 45 min without influencing cooking losses or palatability attributes (P>0.05). VPS, however, improved initial and overall tenderness and reduced the amount of perceptible connective tissue, but increased total cooking losses, reduced juiciness, and intensified flavor (P<0.05).     

收获时间、储藏温度及时间对粳稻南粳5055储藏品质的影响

通过定时检测七个月储藏期的南粳5055含水率、脂肪酸值、发芽率及表面颜色等理化指标,分析收获时间和储藏温度及时间三个因素对南粳5055储藏品质的影响。结果表明,收获时间与储藏温度及时间都对储藏过程中的粳稻含水率及脂肪酸值等重要指标有极显著影响（P < 0.01）,但收获时间对其发芽率影响不显著（P > 0.05）;收获时间、储藏温度及时间与粳稻表面颜色具有较高关联性。不同温度下储藏的粳稻脂肪酸值变化符合化学反应一级动力学模型,比较不同收获时间的南粳5055脂肪酸值增加的活化能（Eα）发现,抽穗后42～66 d收获的粳稻中48、54 d收获的粳稻反应活化能较高。研究表明,除储藏温度和时间外,收获时间也对南粳5055储藏品质有重要的影响。     

The Role of Muscle Proteases and Lipases in Flavor Development During the Processing of Dry-Cured Ham

The processing of dry-cured ham is very complex and involves numerous biochemical reactions that are reviewed in this article. Muscle proteins undergo an intense proteolysis, resulting in a great number of small peptides and high amounts of free amino acids. The enzymes responsible of these changes are proteinases (cathepsins B, D, H, and L and, to a less extent, calpains) and exopeptidases (peptidases and aminopeptidases). Muscle and adipose tissue lipids are also subject to intense lipolysis, generating free fatty acids by the action of lipases that, in a second stage, are transformed to volatiles as a result of oxidation. Sensory profiles of dry-cured ham are strongly affected by these enzymatic reactions. In addition, the activity levels of the muscle enzymes significantly depend on the properties of raw ham, such as age and crossbreeding as well as the process conditions such as temperature, time, water activity, redox potential, and salt content. Thus, the control of the muscle enzyme systems, mainly proteases and lipases, is essential for the standardization of the processing and/or enhancement of flavor quality of dry-cured ham.     

Effect of Storage Temperature on the Stability of Aseptically Packaged Concentrated Orange Juice and Concentrated Orange Drink

Commercial orange drink concentrate and two orange juice concentrates were aseptically packed in flexible bags and stored at 4°, 15°, 22°, and 30°C for 6 months. Ascorbic acid, nonenzymatic browning and sensory quality were measured monthly. Sensory characteristics for drink concentrate deteriorated after 3 and 4 months at 30°C and 22°C, respectively. Juice concentrates were unacceptable after 2 and 5 months at 30°C and 22°C, respectively. Drink concentrate ascorbic acid loss was greater than juice concentrates at 4°, 15°, and 22°C. Changes in nonenzymatic browning as measured by Hunter color and by absorbance at 420 nm were similar to changes in other containers. The quality of refrigerated aseptic drink (15°C) and juice (4°C) was similar to frozen concentrates (?18°C).     

Effects of Deaeration and Storage Temperature on Quality of Aseptically Packaged Guava Puree

Deaeration of aseptically packaged guava puree did not benefit either color or flavor stability but did aid in the retention of ascorbic acid during the first 6 months of storage. The reduction of headspace O₂ was greatest in the samples stored at 23°C followed by lesser decreases in samples stored at 10° and - 18°C. Sensory panel scores for color, Hunter color values, dissolved O₂, headspace O₂, and ascorbic acid were highly correlated with each other showing that color changes were related to O₂ consumption and ascorbic destruction.     

Effect of Tumbling and Tumbling Time on Quality and Microflora of Dry-Cured Hams

Thirty-two intact hams were utilized to study the effects of tumbling and tumbling time (1 hr continuous, 3 hr intermittent, 6 hr intermittent) on the quality and microflora of intact dry-cured hams. Tumbled hams had higher salt concentrations, lower moisture percentages, and showed more muscle separation and excessive surface drying. Sensory panel scores were similar for all treatments except that 3 hr intermittently tumbled hams had higher salt and lower overall satisfaction scores. Tumbling significantly accelerated salt and nitrite penetration during the Fust 2 wk of curing but had little subsequent effect. Tumbled hams generally had lower microbial counts; however, after aging all hams were of acceptable microbial quality.     

Effect of Processing Temperature and Storage Time on Nonfat Dry Milk Proteins

Changes in physicochemical properties of pooled nonfat milk preheated to 63°C (I), 74°C (II), and 85°C (III), before spray-drying were examined. Insoluble material from III contained more protein (particularly at reduced pH) and more coagulated protein-lactose aggregates than either I or II. Soluble material from III was practically depleted of whey proteins which were utilized to form complexes stabilized through disulfide bonds. Milk protein micelles from III were heavier (ca 1 × 10¹¹ g/mole) than either I or II. An unsweetened milk-orange juice blend, which was pasteurized at 63°C for 30 min and stored at 4°C, developed a precipitate which contained more protein and pectin, but less sucrose than the supernatant.     

High Vacuum Flame Sterilized Fruits: Influence of Can Type on Storage Stability of Vacuum Packed Peach and Pear Slices

The feasibility of using enameled tin and tin-free steel (TFS) cans for processing oxygen sensitive fruits by high vacuum flame sterilization was evaluated. Through 18 months storage at ambient temperatures, the appearance and quality of the HVFS peaches and pears remained acceptable for all can types. Fruits packed into plain tin cans appeared brighter and tasted tangier than those packed into TFS or inside-enameled tin cans. Texture, pH and titratable acidity of fruit were not measurably affected by variation in can types. Mechanical deaeration followed by flame sterilization, produced a product with quality comparable to that achieved in flame deaerated packs.