Comparison of shelf life of vacuum-packed pork and beef

The relevance of the intrinsic factors of meat to the sensorial shelf life of vacuum-packed, cold-stored minced pork and beef was investigated. The intrinsic factors studied were the pH and the concentrations of glycogen, glucose, glucose-6-phosphate, l-lactate and fat. The initial bacterial loading was the same on all the meat. High correlations were found between the initial values of pH, fat and l-lactate, respectively, and the rate of spoilage. Using partial least square regression, it was shown that changes in the pH and the concentrations of l-lactate and glucose-6-phosphate during storage were able to explain 68% of the variation observed in the rate of spoilage. No relationship was found between spoilage and the origin of the meat (pork or beef).     

猪肉微波保鲜探讨

应用微波技术对真空包装新鲜猪肉进行处理,通过细菌总数和挥发性盐基氮的测定以及感官评价,探讨鲜猪肉在室温下的货架期。结果表明,微波处理对猪肉保鲜效果不明显。对微波保鲜肉类研究有一定参考价值。     

Effects of lactic and acetic acid salts on quality characteristics of enhanced pork during retail display

The objective of this study was to evaluate the sensory and physical characteristics of pork chops from loins enhanced to 110% of original weight with either (1) potassium lactate, potassium diacetate, phosphate and salt, (2) sodium lactate, phosphate and salt, (3) potassium lactate, phosphate and salt, (4) sodium acetate, phosphate and salt, or (5) phosphate and salt. A trained sensory panel evaluated pork flavor, saltiness, bitterness, soapy flavor, acid flavor, juiciness and tenderness of cooked chops. Visual color of raw chops was also evaluated. After 96 h in display, chops enhanced with lactate/diacetate had significantly lower (P<0.01) aerobic plate counts than control (unpumped) chops, or those pumped with other solutions. Lactate/diacetate-enhanced chops maintained higher a* and b* values during display, and had less visual discoloration after 96 h display. Chops pumped with lactate, acetate or the lactate/diacetate mixture were more tender and juicy, and had more pork flavor than controls or those pumped with phosphate/salt only. There appears to be a significant advantage to using a lactate/diacetate enhancement solution over either lactate or acetate alone.     

Effect of sourdough at different concentrations on quality and shelf life of bread

The objective of this work was to study the effect of sourdough obtained with selected exopolysaccharide (EPS)-producing lactic acid bacteria (LAB) strains on the quality of bread and its shelf life. Two sourdough concentrations were used in order to ascertain the best bread composition. Fresh bread quality was studied by means of microbiological, physical, chemical and mechanical analysis, whereas physical, thermal and mechanical properties were investigated to study the product shelf life. The results showed that dough prepared with 30 g/100 g of sourdough had a negative impact on bread quality properties in the absence of EPS-producing LAB strains, whereas the opposite was observed in the presence of EPS-producing strains: bread samples at 30 g/100 g of sourdough showed higher volume, higher moisture content and better mechanical properties during storage than samples at 20 g/100 g of sourdough. Moreover, 30 g/100 g of sourdough showed a protective effect on bread staling, thus confirming the effect of sourdough concentration and the positive role of EPS on functional properties.     

Trained sensory perception of pork eating quality as affected by fresh and cooked pork quality attributes and end-point cooked temperature

The present study evaluated individual and interactive influences of pork loin (n = 679) ultimate ph (pH), intramuscular fat (IMF), Minolta L∗ color (L∗), Warner-Bratzler shear force (WBSF), and internal cooked temperatures (62.8 °C, 68.3 °C, 73.9 °C, and 79.4 °C) on trained sensory perception of palatability. Logistical regression analyses were used, fitting sensory responses as dependent variables and quality and cooked temperature as independent variables, testing quadratic and interactive effects. Incremental increases in cooked temperature reduced sensory juiciness and tenderness scores by 3.8% and 0.9%, respectively, but did not influence sensory flavor or saltiness scores. An increase of 4.9 N in WBSF, from a base of 14.7 N (lowest) to 58.8 N (greatest) was associated with a 3.7% and 1.8% reduction in sensory tenderness and juiciness scores, respectively, with predicted sensory tenderness scores reduced by 3.55 units when comparing ends of the WBSF range. Modeled sensory responses for loins with pH of 5.40 and 5.60 had reduced tenderness, chewiness, and fat flavor ratings when compared with responses for loins with pH of 5.80 to 6.40, the range indicative of optimal sensory response. Loin IMF and L∗ were significant model effects; however, their influence on sensory attributes was small, with predicted mean sensory responses measurably improved only when comparing 6% and 1% IMF and L∗ values of 46.9 (dark) when compared with 65.0 (pale). Tenderness and juiciness scores, were related to a greater extent to loin WBSF and pH, and to a lesser extent to cooked temperature, IMF and L∗.     

Effect of different dietary levels of natural-source vitamin E in grow-finish pigs on pork quality and shelf life

Improving pork quality and shelf life is important in today’s swine industry because higher levels of DDGS are incorporated into pig diets. Relatively high level of poly-unsaturated fatty acids (PUFA) in DDGS may increase pork susceptibility to lipid oxidation and thus reduce pork shelf life. Antioxidants such as vitamin E may delay the onset of pork lipid oxidation when used as an ingredient in the diet. This experiment examined carcass characteristics, meat quality, shelf life, and color stability in pork from pigs (n = 150) fed five levels of a natural vitamin E (Nova-E) and one level of synthetic vitamin E. Natural vitamin E and synthetic vitamin E had no effect on carcass characteristics or meat quality. Increasing dietary natural vitamin E from 10 to 200 mg/kg decreased lipid oxidation. Lipid oxidation of pork chops and ground pork was similar between pigs fed 40 mg/kg and higher levels of natural vitamin E, indicating no additional benefits from supplementing beyond 40 mg/kg natural vitamin E. Supplementing 200 mg/kg synthetic vitamin E decreased pork lipid oxidation when compared to supplementing 10 mg/kg natural vitamin E. High levels of natural vitamin E or synthetic vitamin E, however, did not prevent discoloration of loin chops. These data indicate that natural vitamin E was effective to help reduce lipid oxidation and the effective minimal level of dietary supplementation appeared to be 40 mg/kg.     

Factors affecting the eating quality of pork

In the last decade studies with the specific objective of improving the sensory quality of pork have come to the forefront of meat research, likely a result of consumer complaints of blandness levelled against modern lean meat and the frequent reference to the more strongly flavored meat that was available years ago. Regardless of the lack of scientific evidence to substantiate or refute these claims, the consumer perception of deteriorated quality is real and presents a challenge for the pork industry. Hence, this review has been undertaken with the aim of providing insight into potential sources of amelioration of the eating quality of fresh pork. Existing works are collated, encompassing animal effects, such as, species, breed, muscle type, fat, and ultimate pH, as well as environmental influences, including pre-slaughter conditions of and housing and exercise, and post-slaughter parameters, such as, electrical stimulation, chilling, and cooking.     

Quality and shelf life evaluation of pork nuggets incorporated with fermented bamboo shoot (Bambusa polymorpha) mince

Pork nuggets were processed by incorporating fermented bamboo shoot mince and their physico-chemical, microbiological and sensory characteristics were evaluated during 35 day storage at refrigeration temperature (4 ± 1 °C). Addition of fermented bamboo shoot significantly affects the pH, moisture, protein, fat, fiber, instrumental color values and texture profiles of nuggets, especially at 6% and 8% addition levels. Nuggets with 6% and 8% FBSM had significantly lower TBARS values at the end of the storage period (i.e. 0.39 and 0.33 mg malonaldehyde/kg respectively) compared to the control (0.84 mg malonaldehyde/kg). Bamboo shoot addition significantly improved the microbial and sensory qualities of the pork nuggets. Incorporation of fermented bamboo shoot at 8% level increased the shelf life of pork nuggets by at least two weeks i.e. from 21 days to 35 days at 4 ± 1 °C compared to the control.     

Effects of muscle cortisol concentration on muscle fiber characteristics, pork quality, and sensory quality of cooked pork

The effect of muscle cortisol concentration on muscle fiber characteristics and technological and sensory quality of pork was investigated. With the exception of the percentage of type IIA fibers, muscle fiber characteristics were not associated to cortisol levels. However, muscle cortisol concentration was positively associated with muscle pH(24h) (r = 0.23, P<0.05) and negatively associated with drip loss (r = -0.49, P<0.001), lightness (r = -0.24, P<0.05), shear force (r = -0.25, P<0.05), and texture profile analysis-hardness (r = -0.35, P<0.01). Additionally, the water-holding capacity of meat samples was affected by cortisol levels, with lower cortisol concentrations associated with less tender samples. These results indicate that the concentration of cortisol in the muscle is related with meat quality as well as the sensory quality of cooked pork.     

Shelf life of fresh foal meat under MAP, overwrap and vacuum packaging conditions

The objective of this study was to investigate the physico-chemical properties, the microbial counts and the sensory properties' changes of foal steaks packed under various conditions. The experimental packaging systems were: (i) vacuum packaging (VP), (ii) overwrap packaging and (iii) two modified atmosphere packaging methods (MAP): high O(2) MAP (80% O(2)+20% CO(2)) and low O(2) MAP (30% O(2)+70% CO(2)). The meat was stored at 2°C during 14days and tested for pH, colour, lipid and protein oxidation, microbial counts and sensory assessment of odour, colour and appearance. Of the two MAP, overwrap and VP, both MAP were the most effective treatments for the inhibition of the total viable counts (TVC), Pseudomonas spp., psychrotrophic aerobic bacteria, lactic acid bacteria, Enterobacteriaceae as well as moulds and yeast. According to the sensory evaluation, foal steaks packed under overwrap and MAP treatments resulted unacceptable after 7days of storage, whereas the vacuum-packed meat was still acceptable. Moreover, the redness value decreased significantly (P<0.001) with all treatments during the storage time, except for the vacuum packs, which increased significantly (P<0.001). Finally, foal steaks from overwrap packaging and MAP conditions had a greater increase of TBAR'S values and carbonyl content during the storage time. High O(2) levels affected foal meat quality negatively, while anaerobic conditions extended the meat's shelf life up to 14days.     

The influence of pork quality traits and muscle fiber characteristics on the eating quality of pork from various breeds

The purpose of this study was to compare parameters associated with pork quality, muscle fiber, and eating quality among various breeds, and to examine if differences in eating quality were associated to pork quality and muscle fiber characteristics. For carcass and pork quality, although there were significant differences among breeds, the values of parameters in all pigs were assigned a normal quality class, a likely outcome of the similarity in the area percentage of type I and IIB fibers. For eating quality, pork loins from Berkshire pigs were more tender and full of pork flavor than Landrace and Yorkshire pigs. Except juiciness and mouth coating, over 20% of the variability in the eating quality parameters can be explained by pork quality traits and muscle fiber characteristics using multiple regression analysis. Furthermore, differences in muscle pH_24 h, cooking loss, shear force, and NPPC marbling score could explain a large proportion of variation in eating quality parameters associated with the texture of pork.     

猪肉品质及其影响因素的研究概况

随着猪肉生产中瘦肉率的提高,以及有害添加剂的饲喂,猪肉品质恶化.而另一方面,人们的保健意识增强,对各种畜禽肉质和风味提出了更高的要求.本文综述了常规肉品质性状,以及品种和营养对它的影响.     

Consumer perceptions of pork eating quality as affected by pork quality attributes and end-point cooked temperature

The study evaluated the interactive and individual effects of fresh pork loin (n = 679) ultimate pH (pH), intramuscular fat (IMF), Minolta L^* color (L^*), Warner–Bratzler shear force (WBS), and four cooked temperatures (62.8 °C, 68.3 °C, 73.9 °C, and 79.4 °C) on consumer (n = 2280) perception of eating quality (n = 13,265 observations). Data were analyzed using ordered logistical regression. Predicted mean responses were consistently near or under five on the 1–8-point end-anchored scale, indicating a neutral perception of pork eating quality regardless of fresh quality or cooked temperature. Responses improved as IMF and pH increased and WBS decreased, whereas L^* did not contribute significantly to variation in responses. Increasing IMF resulted in a very small incremental improvement in responses, but was of practical size only when comparing the least (1%) to the greatest (6%) levels. Loin pH and WBS were primary contributors to consumer perceptions, whereby an incremental increase in pH (0.20 unit) and decrease in WBS (4.9 N) resulted in a 4–5% reduction in the proportion of consumers rating pork as 6 (favorable) on the 8-point scale. No interactions between quality and temperature effects were observed. Increased cooked temperature was negatively (P < 0.05) associated with Overall-Like and Tenderness ratings, but the incremental effect was small. Juiciness-Like and Level responses decreased by 0.50 units as temperature increased across the range. Consumer responses favor pork with lower WBS, greater pH and IMF, and pork cooked to a lower temperature.     

Shelf life determination of Yayik butter fortified with spice extracts

Sage ( Salvia officinalis L.), cinnamon ( Cinnamomum zeylanicum ), rosemary ( Rosmarinus officinalis L.), clove ( Syzygium aromaticum L.), sumac ( Rhus coriaria L.), oregano ( Origanum vulgare L.), ginger ( Zingiber officinale ), caraway ( Cuminum cyminum L.) and thyme ( Thymus vulgaris L.) extracts were added at two concentrations (0.2 and 0.5%) to yayik butter. The butter samples were stored at two different temperatures, 4°C and 25°C. Product acceptability was monitored following the Weibull Hazard sensory method where the end of shelf life was the time at which 50% of panellists found the product unacceptable. Ginger, thyme and cinnamon extracts increased the shelf life of yayik butter and were comparable to the synthetic preservatives sorbic acid and BHA. The shelf life of the samples stored in the refrigerator was approximately twice as long as the samples stored at room temperature.     

Production systems and influence on eating quality of pork

The present paper reviews the available information on the eating quality of pork from the perspective of production systems considered at farm level. Among the specifications differentiating systems having a claim on eating quality, breed, feeding strategy, rearing conditions and slaughter age/weight of the pigs may influence pork eating quality. Specific genetic X environment interactions such as the use of slow growing-fat local breeds reared in extensive conditions, as encountered in local Mediterranean systems, lead to high eating quality of pork and pork products Organic production per se has little influence on the eating quality of pork. Welfare-oriented specifications such as enriched living environment, outdoor access or free-range rearing have limited consequences on pork quality. Because boar taint negatively impacts the consumer acceptability of pork, a total ban on castration to improve animal welfare would be a real challenge for the management of pork quality in those countries where entire male pig production is not currently common.     

Consumers' expected quality and intention to purchase high quality pork meat

Expected quality is believed to be one of the most important factors that influence consumers' intention to purchase food. The present study seeks to explore the concept of pork meat expected quality and compare it with self-stated consumer intention to purchase pork meat. The aim is attempted by means of a field research conducted in Greece, following a conjoint analytic procedure. Results show that quality expectations comply with intention to buy pork, in many aspects. However, several differences have been identified. More specifically, country of origin and marbling appear to be more important for respondents' purchase decisions than they are for their quality evaluations, while the opposite appears to be true for price. Finally, socio-demographic factors such as gender, level of education, place of purchase and consumption habits seem to influence perceptions.     

Shelf life extension of beef retail cuts subjected to an advanced vacuum skin packaging system

Vacuum skin packaging (VSP) is a new and promising technology that includes the instantaneous heating of the upper packaging film immediately before its descent over the meat surface. In the present paper we evaluated this technology for the packaging of a wide variety of beef retail cuts and compared this with traditional vacuum packaging (TVP) performed in parallel. Shelf-life and quality evolution was estimated by analysing three spoilage bacterial groups, an ubiquitous psychrotrophic food pathogen, and three biochemical and physico-chemical attributes throughout 40 days of storage at 4 °C. Statistically-significant lower microbial counts were obtained for all microbial parameters and meat types. The VSP lot exhibited lower pH. This, however, involved a lower water holding capacity and a higher degree of firmness, the latter indicating a limited tenderisation process in the VSP batch. Extended aging times in the carcasses were studied to improving the tenderness of VSP samples. The extension of the aging process prior to VSP may be useful for improving the tenderness of certain meat types and to improve the sensory quality of meat cuts processed under this system.     

Modelling quality variations in commercial Ontario pork production

This study explores the interactions of sensory and nutritional environment with genotype occurring in current commercial pork production in Ontario, Canada, which may interact to result in poor quality meat. The study focussed on identifying factors and signalling mechanisms that contribute to poor meat quality, in order to develop strategies to reduce the incidence of unacceptable product quality. In the first phase of the work reported here, animal behaviour and muscle metabolism studies were related to meat colour, tenderness and water-holding capacity measurements from commercially-produced pigs killed in a commercial packing plant. A partial least squares analysis was used to determine the most important of the principal production variables, peri-mortem biochemical measures and post-mortem carcass condition variables studied, in terms of their influence on water-holding, toughness and colour (L*-value). Variations between producer and kill day at the slaughterhouse were very strong contributors to variability in these three meat quality parameters, followed by pH variations. A second phase of the study is currently underway to characterize patterns of gene expression related to extremes of end-product quality and to reduce quality variations by nutritional and behavioural management strategies.     

Effect of the molecular weight and concentration of chitosan in pork model burgers

Chitosan of high and low molecular weights was added at 0%, 0.25%, 0.5% and 1% concentrations to a burger model system. Burgers were evaluated by physicochemical analysis, cooking characteristic and storage stability. The antioxidant activity of chitosan was studied in vitro. The addition of chitosan influenced pH and color properties, in molecular weight and concentration dependent ways. Cooking properties were significantly affected by the chitosan. High molecular weight chitosan improved all cooking characteristics compared with control samples. Low molecular weight chitosan increased the shelf life of burgers, enhanced the red color and reduced total viable counts, compared with control and high molecular weight chitosan samples. The antioxidant activity of chitosan was dependent on molecular weight and concentration. The results indicate that high molecular weight chitosan (HMWC) improves all cooking characteristics and antioxidant activity while low molecular weight chitosan extends the red color and reduces total viable counts.     

Shelf life of Turkish whey cheese (Lor) under modified atmosphere packaging

In this study, the shelf life of Lor cheese stored under different atmosphere compositions was assessed and compared. Lor cheeses were held in four different atmospheres containing: vacuum packaging (VP), 40% CO₂/60% N₂, 60% CO₂/40% N₂ and 70% CO₂/30% N₂ (modified atmosphere packaging). Control cheeses were stored in air. All cheese samples were kept in the refrigerator at 4°C for 45 days and investigated for physicochemical, microbiological and sensory properties. The acidity index value was significantly higher ( P  < 0.05) in the control and vacuum packaged samples than in those stored for the same period under CO₂. Microbiological results showed that modified atmosphere packaging delayed microbial growth compared with air and VP samples. Of the three modified atmospheres, gas mixtures 60% and 70% CO₂ were the most effective for inhibition of growth of micro-organisms. Sensory evaluation (odour and taste) results showed that Lor cheese packaged under modified atmosphere packaging (60% CO₂/40% N₂ and 70% CO₂/30% N₂ ) retained good characteristics for 45 days of storage, while vacuum and control samples were sensorily unacceptable after 10 days of storage.