Effect of oxygen on aroma volatiles and quality of fresh-cut cantaloupe and honeydew melons

Cantaloupe and honeydew melon cultivars were processed and stored under a high oxygen passive modified atmosphere packaging (MAP) or reduced oxygen controlled atmosphere (CA; 5 kPa O₂ + 10 kPa CO₂ and balance N₂) for 14 days at 5 °C. Atmosphere did not affect softening rate or soluble solids content and had a negligible effect on colour. Volatile compounds known as flavour-important in melons were extracted using stir bar sorptive extraction (SBSE) and quantified via GC–MS. Acetate esters increased more in MAP than in CA. Non-acetate esters increased markedly in both cultivars and storage types. Alcohols were more abundant in honeydew than in cantaloupe. Aldehydes decreased during storage in both cultivars and storage types. Lower O₂ availability under CA conditions likely suppressed some of the esters relevant to the aroma of fresh-cut melon. Results suggest that package O₂ levels are more important in determining aroma than other quality attributes of fresh-cut melon, and high O₂ levels may be required to reveal desirable aroma compounds.     

Effect of lactate-enhancement, modified atmosphere packaging, and muscle source on the internal cooked colour of beef steaks

Earlier studies on lactate-mediated colour stability in beef did not address the possible influence on cooked colour. Our objective was to examine the effect of lactate-enhancement, muscle source, and modified atmosphere packaging (MAP) on the internal cooked colour of beef steaks. Longissimus lumborum (LL) and Psoas major (PM) muscles from 16 (n = 16) beef carcasses (USDA Select) were randomly assigned to 4 enhancement treatments (non-injected control, distilled water-enhanced control, 1.25% and 2.5% lactate), and fabricated into 2.54-cm steaks. Steaks were individually packaged in either vacuum (VP), high-oxygen MAP (HIOX; 80% O₂ + 20% CO₂), or carbon monoxide MAP (CO; 0.4% CO + 19.6% CO₂ + 80% N₂), and stored for 0, 5, or 9 days at 1 °C. At the end of storage, surface and internal colour (visual and instrumental) was measured on raw steaks. Steaks were cooked to an internal temperature of 71 °C, and internal cooked colour (visual and instrumental) was evaluated. Lactate-enhancement at 2.5% level resulted in darker (P < 0.05) cooked interiors than other treatments. Interior cooked redness decreased (P < 0.05) during storage for steaks in VP and HIOX, whereas it was stable for steaks in CO. Our findings indicated that the beef industry could utilise a combination of lactate-enhancement and CO MAP to minimise premature browning in whole-muscle beef steaks.     

Effects of modified atmosphere and vacuum packaging on the growth of spoilage and inoculated pathogenic bacteria on fresh poultry

Fresh chicken breast meats inoculated withYersinia enterocolitica andAeromonas hydrophila were packaged in glass jars either containing different compositions of modified atmospheres (MA) (100% CO₂; 80% CO₂/20% N₂), or in vacuo or containing air, and were stored at 3±1°C and 8±1°C. The changes in gas composition as well asY. enterocolitica, A. hydrophila, total aerobic bacterial, total psychrotrophic, Lactobacilli and Enterobacteriaceae counts were determined after 0,1,3,7,9,11 and 14 days of storage. The results show that while the growth ofY. enterocolitica andA. hydrophila were retarded following MA storage, the pathogens were capable of growth in MA and vacuum storage at both temperatures, for the inoculation levels studied. For total aerobic bacterial counts, there were no differences between the values for chicken breast meats kept in different atmospheres. Being packaged in CO₂ had the greatest inhibitory effect on the growth of psychrotrophic aerobic bacteria during the first 3 days. Lactic acid bacteria levels of samples stored in MA conditions and in vacuo increased rapidly when compared to those levels of samples stored in air. It was also found that the effect of MA storage increased at 3±1°C.     

Influence of the modified atmosphere packaging on shelf life and quality of Navalinda sweet cherry

The benefits of different wrap-films for Navalinda sweet cherry, packaged in small-format (consumer packages), were analysed. A storage and distribution process entailing eight days at 4 °C plus four days at 20 °C was simulated. The cherries were packed in punnets and film-wrapped with one macroperforated film and two microperforated films of 0.30 (MAP.30) and 0.55 (MAP.55) µmol cm/cm² atm day of CO₂ permeability at 0 °C. Packing in MAP at 0 °C did not alter the subsequent respiratory intensity of the fruits at 20 °C; however, the respiratory intensity at 20 °C did increase when the storage temperature was raised to 4 °C. The concentration of CO₂ (%) inside the packets at 20 °C was proportional to the permeability of the films: MAP.30 (21%) and MAP.55 (15%). The microperforated films preserved fruit acidity and firmness while slowing down the darkening of colour, loss of quality and decay. Shelf life was most effectively prolonged with MAP.30 film. However, in view of the levels of hypoxia reached at 20 °C, its use is recommended only in the distribution and marketing processes with failsafe cold chains. The recommendations of use of the films, for the different markets, are expressed in light of the obtained results.     

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 and vacuum packaging on the shelf-life of refrigerated chub mackerel (<Emphasis Type="Italic">Scomber japonicus</Emphasis>): biochemical and sensory attributes

The effect of modified atmosphere packaging (MAP 1: 70% CO₂/30% N₂ and MAP 2: 50% CO₂/30% N₂/20% O₂) and vacuum packaging (VP), on the shelf-life of chub mackerel (Scomber japonicus) fillets stored under refrigeration was studied. Quality assessment was based on sensory analysis and biochemical indices determination. Increase in total volatile basic nitrogen (TVBN) and trimethylamine nitrogen (TMAN) followed the order: MAP 1 < MAP 2 < VP < air (control samples). The presence of oxygen into the fish package (air or MAP) resulted in an increase in the 2-thiobarbituric acid (TBA) values in comparison with samples packaged in the absence of oxygen. The most effective MAP used was MAP 1 which contributed to a considerably slower rate of fish spoilage. Based primarily on odour scores it was observed that raw chub mackerel fillets stored in the presence of air remained acceptable up to ca. 11 days, VP and MAP 2 samples up to ca. 15–16 days, while MAP 1 samples up to ca. 20–21 days of storage. On the other hand, flesh texture and flesh colour of all packaged samples received scores above or equal than the acceptability limit up to ca. 13–14 days of storage.     

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.     

Treatment of Escherichia coli O157:H7 with lactic acid, neutralized electrolyzed oxidizing water and chlorine dioxide followed by growth under sub-optimal conditions of temperature, pH and modified atmosphere

The utilization of sub-lethal decontamination treatments gains more and more interest due to the increased consumers' demand for fresh, minimally processed and convenient food products. These products rely on cold chain and hurdle (combination) technology to provide microbiological safety and quality during their shelf life. To investigate the ability of surviving cells to resuscitate and grow in a food simulating environment, sub-lethal decontamination treatments were coupled with subsequent storage under sub-optimal growth conditions. For this purpose chlorine dioxide (ClO₂) and neutralized electrolyzed oxidizing water (NEW)-treated cultures of Escherichia coli O157:H7 were inoculated in TSB-YE of pH 5.8 and a_w 0.99, and stored at 10 °C, 12.5 °C and 15 °C, under four different atmospheres (0%, 30% and 60% CO₂ balanced with N₂, and air). Due to the severity of injury, lactic acid-treated cells were inoculated in TSB-YE pH 7.0. Data obtained reveal that the fraction of sub-lethally injured E. coli O157:H7 undergoes an additional inhibitory effect during the storage period under of sub-optimal conditions. Observed extension in the lag growth phase was a direct consequence prior sub-lethal injury. The effects of liquid ClO₂ and NEW were less pronounced in comparison to lactic acid. The current study signifies the potential utilization of appropriate combination of different extrinsic and intrinsic factors in the elimination or growth inhibition of food-borne pathogens.