Respiratory dynamics of fresh baby corn (Zea mays L.) under modified atmospheres based on enzyme kinetics

Respiratory properties of fresh black carrot (Dacus Carota L.) based upon non-linear enzyme kinetics approach

The present work was undertaken with an objective to evaluate the impact of temperature on respiration rate of fresh black carrot using a non-linear enzyme kinetics approach. Two different models viz. Arrhenius equation (temperature effect) and enzyme kinetics (effect of temperature and headspace concentration) have been compared for predicting the respiration rate of black carrot. The respiratory behavior of black carrot was assessed using closed system technique at 5, 10 and 15 °C (± 1 °C) temperature and constant relative humidity (RH) of 85%. The O₂ consumption and CO₂ evolution rate values were 39.17, 58.88 and 68.08 ml kg^-1 h^-1; 22.15, 34.63 and 41.86 ml kg^-1 h^-1 after the attainment of steady-state condition at 5, 10 and 15 °C, respectively. The inhibition by evolved CO₂ was found to be predominantly competitive at all temperatures. The average absolute deviation in O₂ consumption and CO₂ evolution rate for Arrhenius model was 3.5% and 5.3% while for enzyme kinetics model was 8.8% and 6.3%, respectively. Dependency of respiration rate of black carrot on temperature was well defined by Arrhenius model. The outcomes of the study can be further utilized to design the MAP (modified atmosphere packages) for fresh black carrot storage at 5 °C with 85% RH.

Active modified atmosphere packaging of yellow bell pepper for retention of physico-chemical quality attributes

This investigation was carried out to evaluate the effect of active and passive modified atmosphere packaging on quality and shelf life of yellow bell pepper fruits. Yellow bell pepper fruits were packaged in 150 gauge LDPE packages with oxygen absorbers for active modification and without oxygen absorber for passive modification of headspace and were stored at different temperatures i.e. 5, 10 and 15 °C and RH of 85 ± 5%. Headspace gas concentration within the packages was monitored regularly. The quality of packaged fruits was studied in terms of physiological loss in weight, firmness, total colour difference antioxidant capacity and total phenolic content. The actively modified packages attained steady state levels of 4.8% O₂ and 7.1% CO₂ on 4th day of storage as compared to passively modified packages in which steady state was not attained even at end of storage period of 12 days. The retention of quality attributes was observed to be higher in active packages than in passive packages. Moreover, the shelf life of actively packaged fruits was enhanced to 28 days as compared to 12 days for passively packaged fruits. The in-pack atmosphere attained in active packages hence proved beneficial in retarding the senescence thereby extending the shelf life.

Modified Atmosphere Packaging and Dark/Light Refrigerated Storage in Green Leafy Vegetables Have an Impact on Nutritional Value

The consumption of zeaxanthin (Z) through a vegetable-rich diet is recommended to reduce the progression of age-related macular degeneration. Due to Z's intrinsic dynamic character that results from its participation in the photoprotective xanthophyll cycle involving the carotenoids violaxanthin, antheraxanthin and zeaxanthin (VAZ), post-harvest handling practices and storage usually retain low amounts of this bioactive compound (compared to the rest of phytochemicals that are, in general, more stable). Thus, the aim of this work was to investigate in important consumed leafy vegetables the effects of different storage conditions on carotenoids (mainly Z) including i) packaging under three modified atmospheres (MAs), ii) light refrigerated supermarket storage and iii) dark refrigerated domestic storage. The results showed that an MA with low O₂ and high CO₂ enhanced the Z content under light. Moreover, both light and dark refrigerated storage showed dynamic and circadian pigment changes that enhanced the total VAZ pool. These results can contribute to generating practical recommendations for industries, supermarkets, and consumers when high Z content is a nutritional target.