The effects of packaging method (vacuum pouch vs. plastic tray) on spoilage in a cook-chill pork-based dish kept under refrigeration

The effects of two packaging methods on the spoilage of a cook-chill pork-based dish kept under refrigeration were studied. Raw pork cuts and pre-cooked tomato sauce were packed under vacuum “sous vide” in polyamide–polypropylene pouches (SV) or into translucent polypropylene trays under modified atmosphere (80% N₂ + 20% CO₂) and sealed with a top film (PT). Samples were cooked inside the pack at an oven temperature/time of 70 °C/7 h, chilled at 3 °C and stored at 2 °C for up to 90 days. Microbial (psychrotrophs, lactic-acid bacteria, Enterobacteriaceae, moulds and yeasts), physical–chemical (pH, water activity and total acidity) and sensory (colour, odour, flavour, texture and acceptance) parameters were determined. Heat penetration was faster in SV (2 °C/min) than in PT (1 °C/min) (core temperature). Both packaging methods were equally effective in protecting against microbial spoilage for 90 day at 2 °C. Minor counts were only detected for lactic-acid bacteria and anaerobic psychrotrophs in SV. No Enterobacteriaceae growth was found. Slight differences between SV and PT in pH and total acidity were observed. SV and PT had similar effects on the sensory preservation of the dishes. A gradual loss of acceptance of the cooked pork and tomato sauce was observed. Rancid flavour in PT and warmed-over-flavour in SV were noted in the final stages of storage. According to acceptance scores, the shelf-life of both SV and PT was 56 days at 2 °C. Both packaging methods can be used to manufacture sous vide meat-based dishes subsequently stored under refrigeration for catering use.     

Chitosan effects on quality properties of Greek style fresh pork sausages

The effect of chitosan (0.5% and 1%) added individually or in combination with nitrites (150 ppm) on microbiological (Total Viable Counts, Lactic acid bacteria, Pseudomonas spp., Brochothrix thermosphacta, Enterobacteriaceae, yeasts and moulds), physicochemical-chemical (pH, chemical composition, lipid oxidation) and sensory properties of fresh pork sausages stored at 4 °C for 28 days was investigated. Chitosan addition resulted in significant (p < 0.05) inhibition of microbial growth, while nitrites did not seem to protect sausages from microbial spoilage. A gradual reduction of nitrites was observed till the end of storage, when nitrites were almost depleted in all nitrite containing samples. The rate of lipid oxidation in fresh pork sausages was significantly decreased (p < 0.05) by addition of increasing levels of chitosan, while samples containing both chitosan and nitrites showed the lowest malondialdehyde (MDA) values, indicating a synergistic antioxidative effect. Consequently, the samples containing the combination of nitrites and chitosan at any level deteriorated less rapidly and were judged as more acceptable than all the other samples.     

Survival during storage and sensory effect of potential probiotic lactic acid bacteria Lactobacillus acidophilus Bauer and Lactobacillus casei Bif3′/ IV in dry fermented pork loins

The objective of this work was to study the survival of two potential probiotic strains (Lactobacillus acidophilus Bauer and Lactobacillus casei Bif3′/IV) in pork loins both with the verification of the possibility of fermented loin development in relation to sensory and microbiological criteria. Six different samples of loins were prepared while as 3 weeks of ripening process and 6 months of storage. The obtained results indicated that highest sensory quality of fermented pork loin after storage was observed in the case of sample produced with L. acidophilus Bauer and with 0.2% glucose addition. The highest count of lactic acid bacteria was observed in the case of the sample with L. casei Bif3′/IV. The results of the study demonstrate that application of probiotic strain L. acidophilus Bauer for pork loins fermentation could assure the satisfying quality regarding sensory and microbiological criteria and can be used for dry fermented loin production.     

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.     

Effect of ultrasonication on microbiological,chemical and sensory properties of raw,thermized and pasteurized milk

The combined effect of ultrasonication and heat treatment on microbiological, chemical and sensory properties of raw, thermized and pasteurized milk was studied. Microbiological parameters monitored included total viable counts and psychrotrophs, chemical parameters included thiobarbituric acid and volatiles determination and sensory evaluation included the monitoring of odour and taste as a function of storage time. Results showed a 1–2.1 log cfu mL^?1 reduction in total viable counts and psychrotrophs for raw, thermized and pasteurized milk up to 6 days of storage. For raw and pasteurized milk ultrasonication resulted in a taste score equal to or lower than that of untreated milk. However, thermized milk, ultrasonicated for 2 min gave a higher taste score than its untreated counter part on day 4 of storage. With regard to lipid oxidation, malondialdehyde ranged between 1.20 and 1.95 mg kg^?1. Finally, volatile compounds identified in all samples were mainly products of lipid oxidation that increased in concentration with sonication and storage time.     

The effect of freezing compared with chilling on selected physico-chemical and sensory properties of sous vide cooked carrots

Sous vide is increasingly used to process convenience foods including ready-meals as it is reputed to give superior quality because of the mild process and the absence of oxygen in the pack. The potential for temperature abuse is greater for sous vide ready-meals than for sous vide catered items as the distribution and retailing chain for the former is usually longer. Freezing sous vide foods is, therefore, a potentially safer alternative to sous vide processed foods followed by chilling. The objective of the current study was to investigate production of sous vide frozen sliced (discs) carrots, with similar quality to sous vide chilled product. Sensory trials were used to determine the acceptable shear texture range (1.0–2.8 kN) for steamed carrots and this was the target texture in the processing trials. A Barriquand Steriflow retort was used for sous vide processing and the optimized conditions using carrot discs were: low temperature blanch (50 °C/30 min; firms product); blanch (90 °C/3 min; inactivates enzymes); sous vide cook (90 °C to core P₉₀¹⁰ values > 4 min and < 6 min); blast freeze (? 35 °C/2 h); and store (? 25 °C). Carrot discs prepared from untreated raw carrots had a firmer texture than those prepared from either blanched or blanched and frozen material. Freezing post-sous vide cooking softened texture in comparison with chilling, but freezing rate (nitrogen; blast; cabinet methods) and frozen storage (9 months) had a minimal effect on product texture and quality. Scanning electron microscopy showed no significant structural differences between sous vide frozen and chilled carrots of similar shear values. Paired comparison sensory testing of sous vide frozen and chilled sliced carrots indicated a significant preference for the latter at the 20-day storage date.Industrial relevance: The trials dealt with the effects of freezing on the quality of sous vide processed carrots. This is of relevance to companies who wish to produce texturally acceptable sous vide frozen or chilled components as part of ready-meals.     

How do culinary methods affect quality and oral processing characteristics of pork ham?

The influences of three different culinary methods: cooking, sous vide and grilling were studied with regards to quality and oral processing characteristics of pork ham. Besides instrumental analysis of color and textural properties of pork ham, sensory panel with 12 trained panelists participated in temporal dominance of sensations, oral processing analysis, boluses collection, particle size distribution analysis, and saliva incorporation. The results revealed that number of chews, mastication time and saliva incorporation are correlated with textural properties and cooking losses. In‐mouth sensation was intertwined with juiciness, fibrousness and firmness depending on the culinary methods. Cooked pork ham showed highest results for hardness and cooking loss. Firmness and fibrousness were dominant sensory attributes. Sous‐vide results show that firmness and juiciness dominated during the first third of consumption time. This corresponds with textural values for lowest values for hardness and cooking, number of chews and total exposure time. Sous‐vide also resulted in lower values for number of chews and total exposure time associated with oral processing.     

Characterizing asymptotic D-values for Salmonella spp. subjected to different heating rates in sous-vide cooked beef

Inactivation rates of a cocktail of Salmonella spp. in sous vide cooked beef exposed to varied ‘come-up’ heating times of zero (control), and 1–3 h from 10 °C to the processing temperature of 58 °C were examined. The observed survival curves, determined for 58 °C, displayed a slight ‘shoulder’ followed by a non-zero asymptotic D-values. Comparisons of the survival curves confirm that the rate of heating can substantially influence the heat resistance of Salmonella spp. While there was no significant difference between the estimated asymptotic D-values for the control and 1-h come-up heating time survival curves, the estimated D-values were significantly larger for the 2- and 3-h come-up heating times curves. The estimated averages of the asymptotic D-values for the control and 1-h come-up time survival curves are approximately 5.7 min; for the 2-h come-up time curves, 7 min; and for the 3-h come-up time curves, 8 min. These findings could have substantial practical importance to food processors in sous vide cooked beef that are processed by slow heating rate/long come-up times and low heating temperatures.     

Effects of supercritical carbon dioxide treatment against generic Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, and E. coli O157:H7 in marinades and marinated pork

This study was conducted to evaluate the effects of supercritical carbon dioxide (SC-CO₂) treatment on soy sauce and hot-pepper paste marinades, as well as in marinated pork products, for the inhibition of generic Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, and E. coli O157:H7. SC-CO₂ was more effective at destroying foodborne pathogens when it was applied to the marinades than the marinated products. SC-CO₂ treatment at 14 MPa and 45 °C for 40 min resulted in a greater reduction in soy sauce (2.52–3.47 log CFU/cm²) than in hot-pepper paste marinade (2.12–2.72 log CFU/cm²). In the case of the marinated pork, when SC-CO₂ was applied at 14 MPa and 45 °C for 40 min, the reduction levels of L. monocytogenes were 2.49 and 1.92 log CFU/cm² in soy sauce and hot-pepper paste marinated pork, respectively. The results should be useful in the meat industry to help increase microbial safety and assure the microbial stability of marinades and marinated products.     

Control of lactic acid bacteria in fermented beverages using lysozyme and nisin: test of traditional beverage boza as a model food system

The objective of this study was to increase quality and limited shelf‐life of boza (3–15 days), a traditional Balkan origin fermented beverage using lysozyme (LYS) and/or nisin (NIS). For this purpose, the effectiveness of NIS, LYS and LYS:NIS combinations was first tested in a broth medium at 4 °C for 3 weeks on Lactobacillus plantarum, one of the frequently isolated lactic acid bacteria in boza. Stability of LYS and NIS in boza, their effects on LAB counts, and chemical and sensory properties of boza were then evaluated during cold storage at 4 °C. Results of LAB counts as well as pH, d ‐ and l ‐lactic acid, and titratable acidity measurements showed that LAB in boza containing NIS (250 μg g^?1) or LYS:NIS (500:250 μg g^?1) could be controlled without reducing LAB counts below 6 log CFU mL^?1 during 2 weeks shelf‐life. In contrast, LYS (500 μg g^?1) alone could not control LAB in boza to delay its acidic spoilage. Positive effects of NIS and LYS:NIS application on quality of boza were also proved with sensory analysis by panelists and e‐nose measurements. This work showed that use of natural GRAS agents in preservation of fermented beverages containing probiotic LAB is possible without affecting their characteristic aroma and flavour.     

Effects of rapid chilling of carcasses and time of deboning on weight loss and technological quality of pork semimembranosus muscle

The effect of rapid air chilling of carcasses in the first 3 h of chilling at −31 °C (then at 2–4 °C, till 24 h post-mortem) and the possibility of earlier deboning (8 h post-mortem) after rapid air chilling, compared to conventional air chilling (at 2–4 °C, till 24 h post-mortem) on weight loss and technological quality (pH value, tenderness, drip loss, cooking loss and colour - L^*a^*b^* values) of pork M. semimembranosus was investigated. Under the rapid chilling conditions, weight loss was 0.8% at 8 h post-mortem and increased to 1.4% at 24 h post-mortem when weight loss was 2.0% under conventional chilling. Carcasses that were rapid chilled had significantly lower (P < 0.001) internal temperature in the deep leg at 4 (25.7 °C), 6 (13.0 °C), 8 (6.2 °C) and 24 h (3.8 °C) post-mortem compared to conventional chill treatment (32.7, 24.2, 19.1 and 5.1 °C, respectively). Rapid chilling reduced significantly (P < 0.05) the rate of pH value decline at 8 h (6.02) post-mortem in M. semimembranosus compared to conventional chill treatment (5.88). Compared to conventional chilling, in M. semimembranosus deboned in different time post-mortem, rapid chilling had a positive significant effect on drip loss (P < 0.05, muscles deboned 8 h post-mortem), cooking loss (P < 0.001) and incidence of pale colour (L^* value). Rapid chilling i.e. rapid chilling and earlier deboning had neither positive nor negative significant effects (P > 0.05) on other investigated technological quality parameters of M. semimembranosus (tenderness, a^* value and b^* value) compared to conventional chilling.     

Effect of Low Dose Irradiation of Pork Loins on the Microflora, Sensory Characteristics and Fat Stability

The effects of low dose (100 krad) irradiation on microflora, sensory characteristics, and development of oxidative rancidity of vacuum packaged pork loins was investigated after irradiation and during low temperature (4°C) storage up to 21 days. Irradiation reduced numbers of mesophiles, psychrotrophs, anaerobic bacteria (P<0.01), and staphylococci (P<0.05), with the effect on mesophiles and psychrotrophic spoilage organisms the greatest. Effect of irradiation on sensory characteristics of pork loin was minimal with no detectable differences between irradiated and nonirradiated pork after 14 days of storage. Irradiation of pork did not affect cooking loss or thiobarbituric acid values.     

On-Site NIR Spectroscopy to Control the Shelf Life of Pork Meat

Control of meat shelf-life includes the time that it remains in the exhibitor of sale (such as the supermarket) until its rejection for the consumer, or withdrawal due to expiry date. Near infrared spectroscopy (NIRS) is one of the most promising techniques for large-scale meat quality control. This study investigated the potential of on-site NIRS portable instrumentation-based models to predict three microbiological parameters to establish if pork meat is acceptable or not for consumption (aerobic Mesophilous microorganisms, Enterobacteriaceae, and lactic acid bacteria) and pH to quality control food preservation and shelf-life extension on intact slices of pork meat packaged under two different modified atmospheres. NIR calibrations were developed by using an on-site Phazir instrument (Polychromix, Wilmington, MA, USA) in the range 1,600–2,400 nm. A total of 252 samples of pork meat slices were directly scanned twice in reflectance mode on trays, once before and another one after removing the film cover at 1, 3, 5, 7, 9, 12, and 15 days of storage. Results showed that spectra of meat acceptable or not for consumption have marked differences around 1,660 nm. NIRS quantitative prediction models showed r ² values between 0.19 and 0.65 for the microbiological parameters assayed. The developed NIRS methodology makes possible on-site prediction of microbiological status of pork meat with a standard error of cross-validation around 1 log cfu/g. Results have shown that modified atmosphere packaging has no influence on calibration statistics.     

Combined effects of thymol, carvacrol and temperature on the quality of non conventional poultry patties

The combined effect of thymol (0–300 ppm), carvacrol (0–300 ppm), and temperature (0–18 °C) on the quality of non conventional poultry patties packaged in air and modified atmosphere (MAP: 40% CO_2; 30%O₂; 30% N₂) was investigated using a simplex centroid mixture design. The patties were monitored for microbiological (total viable count, Enterobacteriaceae, lactic acid bacteria, Pseudomonas spp.) physico-chemical (pH, colour) and sensory attributes. For the patties mixed with the antimicrobials and stored at low temperature (0–3 °C) a reduction of the cell load of about 1–1.5 log cfu/g was observed. The log reduction was lower at the end of storage time and decreased with the increase of the temperature. For the poultry patties packaged in MAP the higher log reduction for Pseudomonas spp. during all the storage time was observed. In both packaging atmospheres the combination of the essential oils and low temperature determined no modification for off-odour during the first 4 days of storage.     

Consumers' sensory acceptability of pork from immunocastrated male pigs

Boar taint is the off-odour or off flavour of cooked pork. Currently, the most common method of controlling boar taint is surgical castration. However, immunocastration has been used in some parts of the world as an alternative to surgical castration. The aim of this study was to evaluate the sensory acceptability of meat from immunocastrated pigs (IM) compared with meat from females (FE), surgically castrated (CM) and entire males (EM). Twenty animals of each type were evaluated by 201 consumers in 20 sessions. Longissimus thoracis muscle of the different animals was cooked in an oven at 180 °C for 10 min. Consumers scored the odour and the flavour of the meat in a 9-point category scale without an intermediate level. There were no significant differences in consumer’s evaluation of meat from IM, CM, and FE. In contrast, EM meat presented a higher percentage of dissatisfied scores and was significantly (P < 0.05) less accepted than meat from CM, IM and FE. Consumers’ acceptability of EM meat was always lower, independently of its androstenone levels. However meat with low levels of androstenone was more accepted that meat with medium or high levels of this substance. It can be concluded that immunocastration produced pork that was accepted by the consumers, and was indistinguishable from pork from CM or FE.     

Using a polynomial model for fungi from table olives

Table olives are one of the most important fermented vegetables in the food industry because of their worldwide economic importance. Enterobacteriaceae, lactic acid bacteria and yeasts are among the most relevant microorganisms involved in olive fermentation determining safety, quality and flavour of the final product. Fungi can play a double role during table olive processing acting as spoilage or desirable microorganisms. This article addresses the effects of some factors (pH, NaCl, temperature, phenols) on the growth/survival of yeasts and moulds, both some wild isolates from olive brine and some yeasts from a public collection (Pichia guilliermondii, P. holstii, Wickerhamomyces anomalus). The research was divided into two steps: a 1st step was aimed at assessing fungal growth by evaluating separately each factor; in a 2nd step, NaCl, pH and temperature were combined through a simple DoE (design of experiment). For this last step, W. anomalus and P. guilliermondii were used as test fungi. Generally, fungi were not inhibited either by temperature, salt or acidic/alkaline pHs. Moreover, the approach of DoE pinpointed that the effect of some factors could experience a shift and change over the time.     

Quality changes during storage of sous vide cooked green beans (Phaseolus vulgaris)

 The acceptability and quality of sous vide cooked green beans (Phaseolus vulgaris) were investigated during chilled storage. A suitable heating procedure was established whereby 2.0-kg packages were heat processed at 90°C for 25 min, corresponding to an average pasteurization value, PV_70,10, of 14 min. During storage for up to 25 days at 3°C drip loss, pH, colour (Minolta L ^* a ^* b ^*), texture (Instron) and microbiological stability were examined and sensory characteristics evaluated by a trained sensory panel. No marked changes in texture, drip loss, pH or microbiological counts were observed but a change of colour from green to olive green was observed by both objective and sensory analyses. This detrimental change in colour, which had begun during the first week, was the limiting factor for shelf-life during storage. Subsequent reheating, however, resulted in further colour changes which partially obscured the initial differences observed during the storage period. Storage for more than 1 week resulted in undesirable quality changes in the odour and flavour of the green beans. Therefore, a maximum shelf-life of 8 days at 3°C was recommended. Inoculation trials showed that psychrotrophic Bacillus cereus were able to germinate and grow to levels of 10⁷ g^–1 in the packages at abuse temperatures (7°C and 17°C), whereafter numbers declined. Received: 21 April 1997     

Seaweeds in yogurt and quark supplementation: influence of five dehydrated edible seaweeds on sensory characteristics

Supplementation of dairy products with seaweeds can contribute to attaining a balanced diet, but they may affect their sensory characteristics. Yogurt and quark were supplemented with dehydrated Himanthalia elongata, Porphyra umbilicalis, Saccharina latissima, Ulva lactuca and Undaria pinnatifida. When odour, flavour and texture were evaluated by panellists, dairy products containing 0.50% U. pinnatifida showed the highest seaweed flavour and the lowest flavour quality, while dairy products containing 0.50% S. latissima showed the lowest seaweed flavour and the highest flavour quality. Seaweed species influenced all yogurt attributes except buttery odour, acid flavour and salty flavour and all quark attributes except yogurt odour, acid flavour and sweet flavour. Logarithmic regressions of seaweed odour and flavour on seaweed concentration (0–1.00%) were the best fit for dairy products containing P. umbilicalis, U. lactuca or U. pinnatifida and linear regressions for those supplemented with H. elongata or S. latissima.     

Extension of the display life of lamb with an antioxidant active packaging

Fresh lamb steaks were treated with three different preparations of natural antioxidants: one group was packaged with a rosemary active film, the second group was packaged with an oregano active film, and the third group was sprayed on the meat surface with a rosemary extract before packaging in a high-oxygen atmosphere. Samples were stored under illumination at 1 ± 1 °C for 13 days. Metmyoglobin formation, lipid oxidation (TBARS), instrumental colour (CIE a^*), psychrotrophic bacterial counts (PCA), sensory discolouration and off-odour were determined. The use of a rosemary extract, a rosemary active film or an oregano active film resulted in enhanced oxidative stability of lamb steaks. Active films with oregano were significantly more efficient than those with rosemary, exerting an effect similar to that of direct addition of the rosemary extract; in fact, they extended fresh odour and colour from 8 to 13 days compared to the control.