Gases and volatile compounds associated with micro-organisms in blown pack spoilage of Brazilian vacuum-packed beef.

UNLABELLED: This study correlated the composition of the spoilage bacterial flora with the main gaseous and volatile organic compounds (VOCs) found in the package headspace of spoiled, chilled, vacuum-packed meat. Fifteen chilled, vacuum-packed beef samples, suffering from blown pack spoilage, were studied using 16S rRNA clone sequencing. More than 50% of the bacteria were identified as lactic acid bacteria (LAB), followed by clostridia and enterobacteria. Fifty-one volatile compounds were detected in the spoiled samples. Although the major spoilage compounds were identified as alcohols and aldehydes, CO2 was identified as the major gas in the spoiled samples by headspace technique. Different species of bacteria contribute to different volatile compounds during meat spoilage. LAB played an important role in blown pack deterioration of the Brazilian beef studied. SIGNIFICANCE AND IMPACT OF THE STUDY: The data generated by this study provided useful information to correlate the microbial contamination of Enterobacteriaceae, lactic acid bacteria and Clostridium with the VOC and gaseous compound production to define, in a faster manner, not only the type of contamination, but also to prevent it.

Behavior of flavonols and carotenoids of minimally processed kale leaves during storage in passive modified atmosphere packaging.

Minimally processed kale leaves were packed in passive modified atmosphere and stored at 3 conditions: 1 °C in the dark and 11 °C with or without light exposure. The products were evaluated during storage in terms of headspace gas composition, sensory attributes, flavonol, and carotenoid contents. The sensory quality decreased slightly during 17 d at 1 °C in the dark. At 11 °C, the vegetable shelf life was predicted to be 6 d in the dark and 3 d with light. Quercetin and kaempferol were stable during storage for 15 d at 1 °C in the absence of light. At 11 °C in the dark, quercetin was stable during 10 d, increasing slightly on the 8th day. Kaempferol decreased up to the 5th day but increased on the 8th day, decreasing again on the 10th day. After 5 d at 11 °C under light, the flavonol levels were significantly higher than those of the initial values. Neoxanthin and violaxanthin did not change significantly after 15 d at 1 °C in the dark. Lutein and ß-carotene, however, decreased 7.1% and 11.3%, respectively. At 11 °C in the dark, neoxanthin, violaxanthin, lutein, and ß-carotene decreased 16.1%, 13.2%, 24.1%, and 23.7% after 10 d, respectively. At 11 °C under light, neoxanthin and lutein had a slight increase while violaxanthin and ß-carotene decreased 23.1% and 16.5% after 5 d. Practical Application: Passive modified atmosphere packaging together with refrigeration can extend the shelf life of minimally processed kale, retaining the health-promoting compounds, flavonols and carotenoids. Quercetin, kaempferol, neoxanthin, and violaxanthin are stable and lutein and ß-carotene slightly reduced.