Effect of exposure to light on physico-chemical quality attributes of sliced dry-cured Iberian ham under different packaging systems

Dry-cured Iberian ham slices were stored under vacuum and under two different atmospheres (N₂ = 70% N₂ + 30% CO₂; Ar = 70% Ar + 30% CO₂) and exposed to lightness or darkness. Physico-chemical, sensory and microbial analysis was carried out throughout 60 days storage. Vacuum samples showed the highest a*-value compared to N₂ and Ar after 30 (P < 0.05) and 60 days (P < 0.05). The influence of illumination during storage was evident after 60 days of storage, L* and a*-values being lower (P < 0.01) in hams exposed to light than those kept in darkness, which can be ascribed to the lower nitrosylmioglobin content in samples exposed to light after 60 days (P = 0.001). Ham slices stored in darkness showed the lowest TBARS values (P < 0.05) and hexanal content (P < 0.05) after 60 days. Slices of ham packed in vacuum showed lower TBARS values than N₂ and Ar batches (P = 0.001), these samples being perceived as more rancid (P < 0.05). The rest of the sensory attributes were not generally affected by gas mixture or illumination (P > 0.05).     

Effects of bactericides and modified atmosphere packaging on shelf-life of Chinese shrimp (Fenneropenaeus chinensis)

Effects of different bactericides and modified atmosphere packaging (MAP) on aerobic plate counts (APCs), total volatile base-nitrogen (TVB-N) and organoleptic evaluation of overall acceptable score (OA score) of Chinese shrimp (Fenneropenaeus chinensis) during cold storage were investigated. Results indicated that APC in MAP(40%CO₂/30%O₂/30%N₂) shrimp treated with compound bactericide reached 10⁷ cfu/g on the 13th day of storage, while that of ozonated water or water control treatments exceed 10⁷ cfu/g on the 9th day. APC in shrimps treated with MAP (40%CO₂/30%O₂/30%N₂) or 100%CO₂ after soaking with compound bactericide reached close to 10⁷ cfu/g at day 13, while that of air treatment exceed 10⁷ cfu/g. TVB-N value in MAP(40%CO₂/30%O₂/30%N₂) shrimp treated with compound bactericide was slightly higher than the upper threshold of 30 mg/100 g on the 17th day, while that of ozonated water treatment or water control increased to or over the threshold value on the 9th day. TVB-N value in shrimps treated with MAP (40%CO₂/30%O₂/30%N₂) or 100%CO₂ after soaking with compound bactericide were significantly lower than that of air control on the 17th day (P ≤ 0.01), with a value of 33.6 mg/100 g and 42-47.6 mg/100 g respectively, compared to 78.4-86.8 mg/100 g in air control. The lowest OA score of MAP(40%CO₂/30%O₂/30%N₂) whole and decapitated shrimps treated with compound bactericide appeared on the 17th and 21th day, respectively, compared with the 9th day in whole shrimp and the 13th day in decapitated shrimps treated with ozonated water and water control. The lowest OA score of whole and decapitated shrimps treated with MAP (40%CO₂/30%O₂/30%N₂) or 100%CO₂ after soaking with compound bactericide appeared on the 17th and 21th day, respectively, compared with the 13th and 17th day in air control. In conclusion, when combined the parameters determined together, the shelf-life of Chinese shrimp at 2 ± 1 °C, either whole or decapitated, treated with MAP (40%CO₂/30%O₂/30%N₂) and 100%CO₂ after soaking with compound bactericide were 13 and 17 days, respectively.     

Effect of modified atmosphere packaging on microbial growth,quality and enzymatic defence of sanitiser washed fresh coriander

Fresh coriander samples were washed in an aqueous chlorine dioxide solution and stored in modified atmosphere packaging (MAP) with air (T0), 4%O₂ + 3%CO₂ + 93%N₂ (T1); 10%O₂ + 3%CO₂ + 87%N₂ (T2); 15%O₂ + 3%CO₂ + 82%N₂ (T3); 20%O₂ + 3%CO₂ + 77%N₂ (T4) at 4 °C for 14 days. After 14 days, the ascorbic acid contents in samples were 24.8 (T3), 22.4 (T4), 19.6 (T0), 18.2 (T2) and 8.8 (T1) mg/100 g; the total phenol contents were 59.9 (T3), 53.8 (T0), 50.1 (T4), 44.8 (T2) and 39.3 (T1) mg gallic acid/100 g; and the total chlorophyll contents were 1.60 (T3), 1.52 (T4), 1.05 (T2), 0.91 (T0) and 0.63 (T1) mg g^?1 respectively. T3 treatment resulted in the best colour maintenance, the least bacterial growth, and the highest activities of superoxide dismutase and catalase throughout the storage period as compared to others. The data revealed that the T3 MAP condition in combination of aqueous chlorine dioxide washing significantly (P < 0.05) maintained the quality and extended the shelf life of fresh coriander.     

Effect of different gas stunning methods on Manchega suckling lamb meat packed under different modified atmospheres

Forty-nine Manchega breed male suckling lambs were used in this experiment. The effect of CO₂ concentration and exposure time at stunning [80% CO₂ for 90 s (G1); 90% CO₂ for 90 s (G2); 90% CO₂ for 60 s (G3); 80% CO₂ for 60 s (G4)] plus an electrically stunned control group (G5) was assessed for pH, colour (L^∗, a^∗, b^∗, C^∗ and h^∗), water holding capacity (WHC), drip loss (DL), cooking loss (CL) and shear force (SF) in samples packed under two different types of modified atmospheres (MA: MA A: 70%O₂ + 30%CO₂; MA B: 69.3%N₂ + 30%CO₂ + 0.7%CO) at 7, 14 and 21 d post-packaging. The lowest pH was found in G4 and in G5. The highest WHC and the lowest CL were found in G2 and G3 groups (P < 0.05). Modified atmospheres did not affect on pH, WHC, CL and DL, although a significant effect (P < 0.001) on colour was found at all the analysis times. Both the type of stunning and the modified atmosphere affected SF values.     

Influence of modified atmosphere packaging on the chilled shelf life of gutted farmed bass (Dicentrarchus labrax)

The effect of MAP on quality changes of gutted farmed bass when stored at 3 °C were investigated for up to 9 days. Gutted farmed bass was packed with six different atmospheres (0%O₂–70%CO₂; 20%O₂–70%CO₂; 30%O₂–60%CO₂; 40%O₂–60%CO₂; 30%O₂–50%CO₂; 21%O₂–0%CO₂). Headspace gas composition (O₂%; CO₂%), aerobic mesophilic bacteria (AMB) and Enterobacteriaceae, pH, water loss, flesh moisture content, colour, stiffness, odour and eyes appearance were assessed by means of instrumental and sensory analysis after 0, 2, 5, 7 and 9 days of storage. Atmosphere composed of 30% of O₂ and 50% of CO₂ was the best one to preserve the quality of the gutted farmed bass. PCA was an effectively instrument to classify gutted bass samples on the bases of quality changes. The effect of the time was explained by the factor 1, whereas the fish were clearly classified along factor 2 in relation to storage atmosphere.     

Effects of high CO2 and low O2 atmospheres on the berry drop of ‘Kyoho’ grapes

To investigate the effects of low O₂ and high CO₂ atmospheres on the berry drop of ‘Kyoho’ grapes (Vitis vinifera X V. labrusca), changes of fruit detachment force (FDF) and berry abscission and enzyme activities in the abscission zone were examined during 60 days of storage in air (control), 4%O₂ + 9%CO₂ or 4%O₂ + 30%CO₂ at 0 °C and 95%relative humidity. There was a high negative correlation between FDF and berry drop. Cellulase activity increased over time and was closely correlated with berry abscission. Polygalacturonase (PG) activity rose markedly for the first 30 days and then remained relatively constant. Peroxidase (POD) activity dropped significantly for the first 15 days and subsequently rose sharply (P < 0.05). Cellulase, PG and POD activities were the lowest in fruits in 4%O₂ + 30%CO₂, followed by 4%O₂ + 9%CO₂ and air storage. Pectinesterase (PE) maintained a basal level of activity and there were no significant differences among three treatments (P < 0.05). Compared to air control, the combined effects of the lower level of O₂ and the higher level of CO₂ suppressed the activities of cellulase, PG and POD, maintained greater FDF, and reduced berry abscission during storage.     

Shelf-stability enhancement of precooked red claw crayfish (Cherax quadricarinatus) tails by modified CO2/O2/N2 gas packaging

Three types of packaging systems were compared for their influence on the storage stability (2 °C) of precooked and peeled red claw crayfish tails. Modified atmosphere packaging (MAP; with 80%CO₂/10%O₂/10%N₂) almost totally inhibited the growth of aerobic bacteria and coliforms when compared with aerobic polyvinylchloride packaging (PVCP) and vacuum packaging (VP). MAP also prevented a pH rise, purge loss, and texture toughening or softening of stored red claw when compared with PVCP or VP (P<0.05). Lipid oxidation was minimal in all three packaging systems. Thus, MAP offers an attractive means to preserve the shelf life of precooked red claw stored under refrigerated retail display conditions.     

Effect of chill storage and modified atmosphere packaging (MAP) on antioxidant activity,anthocyanins, carotenoids,phenolics and sensory quality of ready-to-eat shredded orange and purple carrots

Ready-to-eat shredded orange and purple carrots, packed in air (control), or in modified atmosphere packaging [MAP; (90%N₂ + 5%O₂ + 5%CO₂ and 95%O₂ + 5%CO₂)], and stored chilled for up to 13 days, were examined for their antioxidant activity and contents of anthocyanins, carotenoids and phenolics, as well as sensory quality. Total antioxidant activity, carotenoids and phenolics of purple carrots were initially 2.8-, 2.3- and 2.9-fold higher than orange carrots, respectively. Total antioxidant activity remained relatively constant in orange carrots during storage under all treatment conditions, whereas a highly significant decrease (P<0.01) in (95%O₂ + 5%CO₂)-treated purple carrots was observed. The content of anthocyanin, only found in purple carrots, was decreased slightly during the storage period, and this was particularly significant in the 95%O₂ + 5%CO₂ treatment. In both orange and purple carrots, loss of total carotenoids occurred in the 95%O₂ + 5%CO₂ treatment. Total phenolic content of purple carrots increased at a much higher rate during storage than orange carrots. The MAP treatment (90%N₂ + 5%O₂ + 5%CO₂) gave better sensory quality and extended shelf-life for purple carrots (∼2–3 days longer shelf-life than other treatments,) but, no difference was observed for orange carrots. Shredded purple carrot can be stored under 90%N₂ + 5%CO₂ + 5%O₂ treatment for up to 10 days and high nitrogen treatment may be used in maintaining the storage quality of shredded purple carrots. Thus, purple carrots may be used in place of orange carrots to take advantage of their nutraceutical components.     

Effect of Vacuum and Modified Atmosphere on Enterobacteriaceae Count Determined in Rainbow Trout (Oncorhynchus Mykiss) and Carp (Cyprinus Carpio) Steaks

The aim of our research was to determine the presence and examine the change in total number of Enterobacteriaceae in trout and carp cuts packed in vacuum and modified atmosphere. To conduct the study, three sample groups of cleaned trout and carp cuts were formed. The first two groups were packaged in modified atmospheres with different gas ratios: 60%CO₂+40%N₂ (I group) and 40%CO₂+60%N₂ (II group), whereas the third group of fish cuts were vacuum packaged. Our results suggest that modified atmosphere packaging of fresh fish with an appropriate percentage of CO₂ might reduce the risk of poisoning people with Enterobacteriaceae.     

Quality parameters and shelf-life of smoked Dalmatian dry-cured ham packed in bio-based and plastic bilayer pouches

Traditional Dalmatian dry-cured ham (prosciutto) was packaged under modified atmosphere, MAP (30%CO₂/70%N₂) and vacuum, in commercial polyamide/polyethylene (PA/PE) and biodegradable poly(lactic acid) (PLA) material. Samples were stored at 4 °C for 180 days and the effect of packaging materials and methods on various quality parameters was studied. The least changes were observed for PA/PE for both packaging methods. The pH, moisture content, colour parameters, TBARS and DNPH values of dry-cured ham packed in PLA were significantly affected already after 1 month in MAP and after 3 months in vacuum packaging. Similar changes in the above parameters were also observed in the control sample (packed in air-PA/PE) while vacuum-PA/PE and MAP-PA/PE showed significantly better results. The instrumental analyses agreed with the sensory panel results where appearance, taste, texture and overall acceptability of PLA samples decreased significantly already after 2 months of storage. For both, MAP-PA/PE and vacuum-PA/PE samples, the shelf-life was estimated to be 5 months.     

Effects of lactate and modified atmospheric packaging on premature browning in cooked ground beef patties

Our objectives were to determine the effects of lactate and modified atmosphere packaging on raw surface color, lipid oxidation, and internal cooked color of ground beef patties. Eight chubs (85% lean) were divided in half and each half was either assigned to the control (no lactate) or mixed with 2.5% lactate (w/w). Following treatment, patties were prepared and packaged in either vacuum, PVC (atmospheric oxygen level), high-oxygen (80% O₂ + 20% CO₂), or 0.4% CO (30% CO₂ + 69.6% N₂) and stored for 0, 2, or 4 days at 2 °C. After storage, raw surface color and lipid oxidation were measured and patties were cooked to either 66 °C or 71 °C. Lactate improved (p < 0.05) color stability of PVC, high-oxygen, and vacuum packaged raw patties, but had no effect (p > 0.05) on the a∗ values and visual color scores of patties in 0.4% CO. Lactate decreased (p < 0.05) lipid oxidation in all packaging atmospheres. Nevertheless, high-oxygen and PVC-packaged patties had more (p < 0.05) lipid oxidation than patties in CO and vacuum. Lactate had no effect (p > 0.05) on premature browning, whereas patties packaged in high-oxygen demonstrated premature browning. Conversely, cooked patties in 0.4% CO and vacuum were more red (p < 0.05) than both high-oxygen and PVC-packaged patties. Although lactate improved raw color stability, it did not minimize premature browning in cooked ground beef patties.     

Effects of aw at packaging time and atmosphere composition on aroma profile,biogenic amine content and microbiological features of dry fermented sausages

The aim was to evaluate the effects of different water contents (corresponding to a_w 0.940, 0.914, 0.895 and 0.875) of sausages at different times on the characteristics of typical Italian dry fermented sausages packaged under two different modified atmospheres (MAP) (100%N₂ or 30%CO₂/70%N₂). During ripening and storage, samples were analyzed to evaluate pH and a_w changes, microbial population, biogenic amine (BA) accumulation and aroma profile.     

Effect of varying oxygen concentrations on the shelf-life of fresh pork sausages packaged in modified atmosphere

A total of 105 fresh pork sausages were packaged in atmospheres varying in oxygen concentration, using the following mixtures (%O₂/%CO₂/%N₂): 0/20/80, 0/20/80 + O₂ scavenger, 20/20/60, 40/20/40, 60/20/20, and 80/20/0. In addition, two batches were subjected to vacuum packaging or over-wrap with O₂-permeable film. They were stored for 20 days at 2 ± 1 °C in the dark. Values of pH, CIE L*, a* and b* color parameters, surface metmyoglobin percentage, TBA-reactive substances, psychrotroph aerobe bacterial numbers and sensory discoloration and off-odor were assessed throughout storage. Packaging in the absence of O₂, either under vacuum or in atmosphere with O₂ scavenger, led to extension of shelf-life in terms of both color and odor stability due to low oxidation rates. Increase of O₂ caused a significant enhancement of oxidation, decrease of shelf-life due to discoloration and off-odor development. The highest O₂ concentration gave rise to a significant color improvement, though only for a limited period of 8 days.     

Effect of different temperatures and storage atmospheres on Coratina olive oil quality

Olives (Olea europaea cv. Coratina) used for oil production were stored for 30 days at three different temperatures and under different atmospheres (ambient temperature, 5 °C with a flux of humidified air, 5 °C with a flux of 3%O₂ + 5%CO₂). The olives were kept in jars used for fruit storage, each with a capacity for 1.5 kg of olives.     

Sensory and biochemical aspects of quality of whole bigeye tuna (Thunnus obesus) during bulk storage in controlled atmospheres

The quality of whole ungutted bigeye tuna (Thunnus obesus) during bulk storage in controlled atmospheres containing either of two gas mixes (60%CO₂/15%O₂/25%N₂ and 40%CO₂/40%O₂/20%N₂) was evaluated by biochemical and sensory changes. At day 33 of storage, none of the lots were rejected on the basis of the target biochemical indices (pH, trimethylamine nitrogen (TMA-N), total volatile base nitrogen (TVB-N) and histamine) or the tasting panel scores. However, the control and the controlled atmosphere-stored lots were rejected upon inspection at 13 and 22 days, respectively. Scores for the various target biochemical parameters were highest (p<0.05) in the control, followed by the lot stored in gas mix two, which had the lower CO₂ concentration. There were changes (p<0.05) in the levels of biogenic amines (tyramine, histamine, cadaverine and agmatine) in the course of storage, but pH, TMA-N and TVB-N remained constant. Histamine levels exceeded 100 μg/g for the control fish and in gas mix one towards the end of storage. Histamine, cadaverine and agmatine could be used as quality indices for tuna stored in ice and atmospheres. Cadaverine and agmatine could also be used as freshness indices.     

Retardation of quality changes of Pacific white shrimp by green tea extract treatment and modified atmosphere packaging during refrigerated storage

The effect of modified atmosphere packaging (MAP) on the quality changes of Pacific white shrimp (Litopenaeus vannamei) treated with or without green tea extract (1 g/L; GTE) in combination with or without ascorbic acid (0.05 g/L; AA) during refrigerated storage of 10 days was investigated. Shrimp without treatment stored under MAP had lowered psychrotrophic bacteria, enterobacteriaceae and H₂S-producing bacteria count (P < 0.05) but similar lactic acid bacteria count (P > 0.05), in comparison with shrimp stored in air (control). The coincidental lowered rate of increase in pH, total volatile base (TVB) content and thiobarbituric acid reactive substances (TBARS) were obtained in shrimp stored under MAP (P < 0.05). However, MAP slightly lowered melanosis formation and improved likeness score to some extent. When shrimp were treated with GTE and stored under MAP, the lower microbiological and chemical changes as well as the lowest melanosis formation were observed, compared to shrimp kept under MAP without treatment and the control (P < 0.05). GTE treatment in combination with MAP could retard chemical changes and melanosis formation, regardless of AA incorporation (P > 0.05). Nevertheless, GTE in combination with AA had higher inhibition on microbial growth and yielded the shrimp with higher likeness, compared with the other treatments (P < 0.05). Therefore, shrimp treated with GTE in combination with AA prior to MAP had the lowest losses in quality during refrigerated storage.     

Prediction of lean and fat composition in swine carcasses from ham area measurements with image analysis

Video images of ham cross-sections were recorded from 71 pork carcasses (ranging in weight from 72 to 119 kg). Three sets of prediction equations were developed to estimate pork carcass lean and fat composition from video image analysis (VIA) of ham cross-sectional area measurements, 10th rib back fat depth (TENFAT) and hot carcass weight (HCKg). Carcass data of dissected lean and fat in the four primal cuts (ham, loin, Boston button and picnic shoulder) were used as dependent variables in establishing regression equations. The first set of equations combined VIA ham measurements and total ham weight (HTKg). Regression models containing the single variable HTKg times ham percentage lean area (Vol. 1) or HTKg times ham percentage fat area (Vol. 2) accounted for 88% and 68% of the variation in total carcass lean weight (CLKg) and total carcass fat weight (CFKg) from the right side of each carcass, respectively. The second set of equations combined VIA ham measurements and TENFAT (cm). Multiple regression models involving TENFAT, Vol. 1, and Vol. 2 accounted for 91% and 90% of the variation in CLKg and CFKg. The third set of equations used VIA ham measurements, TENFAT and HCKg. Carcass lean weight was best predicted by HCKg, TENFAT, and ham lean area (HLA) (R² = .92). Carcass fat weight was best predicted by HCKg, TENFAT, and Vol. 2 (R² = .91). Overall correlations showed a high association between Vol. 1 and CLKg (r = .94, P < .0001) and Vol. 2 and CFKg (r = .83, P < .0001). Ham lean area was related to CLKg (r = .74, P < .0001) and ham fat area to CFKg (r = .81, P < .0001). The results of this study indicated video image analysis of ham cross-section slices combined with backfat depth at the 10th rib can be used for accurate estimation of total carcass lean or fat composition.     

Modelling the fate of Listeria Monocytogenes in Beef Meat Stored at Refrigeration Temperatures under Different Packaging Conditions

The objective of this study was to model the fate of L. monocytogenes inoculated in beef at two concentrations (2.5 and 4.0 log CFU/g), packaged under aerobic, vacuum and three modified atmosphere combinations – 70%O₂/20%CO₂/10%N₂, 50%O₂/40%C O₂/10%N₂ and 30%O₂/60%CO₂/10%N₂, and refrigerated at a normal temperature (4°C) and at a mild abuse temperature (9°C). An omnibus model based on the three-parameter Weibull equation proved statistically that L. monocytogenes survives better in vacuum (VP) than in aerobic conditions, although without significant difference in its ability to survive in the temperature range between 4°C and 9°C. Furthermore, regardless of the refrigeration temperature, the presence of CO₂ in package atmosphere exerted a bactericidal effect on L. monocytogenes cells, being approximately 1.5 log of reduction when storage time reached 10 days. Since the pathogen can survive in VP/MAP beef at refrigerated storage, there is a need of maintaining its numbers below 100 CFU/g before packaging by placing efforts on the implementation of control measures during processing.     

Effect of modified atmosphere and vacuum packaging on some quality characteristics and the shelf-life of “morcilla”, a typical cooked blood sausage

The effect of modified atmosphere and vacuum packaging on the shelf-life of “morcilla”, a traditional cooked blood sausage, was investigated. A total of 99 “morcillas” were packaged under vacuum and in modified atmosphere using three different gas mixtures: 15:35:50/O₂:N₂:CO₂ (atmosphere 1), 60:40/N₂:CO₂ (atmosphere 2) and 40:60/N₂:CO₂ (atmosphere 3), and stored during 2, 4, 6 and 8 weeks at 4 °C. Shelf life evaluation was based on pH, water activity (a_w), colour (CIE L*, a*, b*, C* and h*), TBARS formation and microbial counts. The results indicated that, in general, storage time affected (P < 0.05) all parameters whereas no significant differences were observed (P > 0.05) among packaging conditions. Based on the microbial counts, the shelf-life of “morcilla” would be greater than 8 weeks for all packaging conditions. Samples packaged with high CO₂ concentrations (40:60/N₂:CO₂) showed the lowest values of TBARS at the end of storage.     

Packaging-specific influence of chitosan on color stability and lipid oxidation in refrigerated ground beef

We examined the influence of chitosan on lipid oxidation and color stability of ground beef stored in different modified atmosphere packaging (MAP) systems. Ground beef patties with chitosan (1%) or without chitosan (control) were packaged either in high-oxygen MAP (HIOX; 80% O₂ + 20% CO₂), carbon monoxide MAP (CO; 0.4% CO + 19.6% CO₂ + 80% N₂), vacuum (VP), or aerobic packaging (PVC) and stored at 1 °C. Chitosan increased (P < 0.05) redness of patties stored in PVC and CO, whereas it had no effect (P > 0.05) in HIOX. Chitosan patties demonstrated lower (P < 0.05) lipid oxidation than controls in all packaging. Control patties in PVC and HIOX exhibited greater (P < 0.05) lipid oxidation than those in VP and CO, whereas chitosan patties in different packaging systems were not different (P > 0.05) from each other. Our findings suggested that antioxidant effects of chitosan on ground beef are packaging-specific.