|Moderate vacuum packaging of fresh-cut mangoes (Mangifera indica L.)
Paper Presenter: Neermala Nallee, AREU
Neermala Nallee, Agricultural Research and Extension Unit, Quatre Bornes and Navindra Boodia, Faculty of Agriculture, University of Mauritius, Réduit
Fresh-cut products are defined as fruits or vegetables that have been freshly cut, washed and packaged that offer consumers a nutritious, convenient and fresh-like product (Gimenez et al., 2003). Consumption of fresh-cut fruits and vegetables has increased considerably during the recent years (Gil, Conesa and Artés, 2001). The main driving force is the growing need for fresh, healthier, convenient, and preservative-free prepared produce (Jaxsens et al, 2001).
Fresh-cut products have however shorter shelf life than whole fruits and vegetables due to the physiological changes that occur in wounded tissues (Chien et al, 2007; Soliva-Fortuny et al, 2002; Gorny et al, 2002). Since consumers are looking for fresh-cut products without the use of preservatives (Martinez-Ferrer et al, 2002), preservation of these products pauses a researchable challenge. Matin-Belloso and Soliva Fortuny (2006) proposed the use of edible coating as a complement to modified atmosphere packaging (MAP) systems as a good alternative for improving the microbial stability and quality of fresh-cut fruits. Scientific literature on combining MAP system with an edible coating is scanty.
In the present study, the potential of combining the edible coating NatureSealTM with moderate vacuum packaging (a subset of MAP system) on the preservation of fresh-cut mangoes will be investigated. The objectives of the study were to:
·Characterise the Dauphiné and Early Gold variety in terms of selected physico-chemical parameters.
·Determine, based on physico-chemical characterisation, the mango variety that is more suitable for processing.
·Evaluate the effectiveness of combining moderate vacuum packaging (MVP) with a natural edible coating in extending the shelf life of fresh-cut mango slices
·Determine the microbiological quality of the fresh-cut slices upon storage at 5oC.
Physico-chemical characterization was determined on semi-ripe Dauphiné and Early Gold varieties. Criteria used for characterization were weight, length, width, pulp to peel ratio, pulp to seed ratio, firmness, colour, pH, titratable acidity, total soluble solids, ascorbic acid content and percent moisture content.
For fresh-cut processing, sample preparation consisted of washing, hand peeling, slicing, disinfecting, dipping in test solutions, MVP and storage at 5 oC. Control consisted of mango slices dipped in water and packed without vacuum (1013 mbar atmospheric pressure). Samples were taken on day 0, 2, 4, 7 and 8 for destructive analysis. Firmness, colour, total soluble solids, pH, titratable acidity, total viable count and yeast & mould count were also evaluated.
Early Gold variety was found to be more suitable for processing since it had significantly higher weight, length, width, pulp to peel ratio and pulp to seed ratio, TSS, titratable acidity and ascorbic acid content compared to Dauphiné. No significant difference was noted for colour, firmness pH and percent moisture content. Evaluation of the fresh-cut slices time showed that texture decreased significantly (p<0.05) with time but no significant difference among the different treatments was observed. The softening could be due to the action of endogenous enzymes related to cell wall degradation. In fact, texture degradation has been closely correlated to ripening processes. During ripening, the fruit cell is overtaken by a rapid synthesis of the enzyme and a subsequent release of soluble calcium leading to softening (Soliva-Fortuny et al., 2002). Colour did not change significantly with storage days (p>0.05), however there was clear evidence of interaction effect between NatureSealTM and moderate vacuum treatment. The purpose of edible coating is to inhibit migration of moisture, oxygen, carbon dioxide and any other solute materials.
Regarding TSS, pH and titratable acidity, only NatureSealTM treatment showed to be significantly different (p<0.05), however TSS did not change significantly with storage days (p>0.05). NatureSealTM did not help in controlling the proliferation of microorganisms (p>0.05) since it does not contain any antimicrobial agent. For both total viable count and yeast and mould count however, significant difference was obtained when MVP was used (p<0.05). The lower O2 availability in MVP slows the growth of aerobic microorganisms and stabilizes the produce. Martin-Belloso and Soliva-Fortuny (2006) reported that low oxygen atmospheres effectively reduce the proliferation of aerobic bacteria while high carbon dioxide atmospheres inhibit most aerobic microorganisms especially gram-negative bacteria and moulds.
At 5 oC, the shelf life of fresh-cut mango slices was of 2 days for the control and treatment with MVP treatment only. On the other hand, NatureSealTM treatment gave a shelf life of 4 days. No added beneficial effect on shelf life was obtained when both NatureSealTM and MVP were used.
Significance of study
MVP of fresh-cut horticultural commodities for export is viewed as a promising avenue. The government is encouraging the development and expansion of local fruit production to satisfy growing domestic needs and to encourage export. In addition more research is being encouraged in postharvest techniques and value addition to our local produce. This study can be useful to those entrepreneurs who seek to invest in fresh-cut processing of exotic commodities like pineapple, breadfruit and palm cabbage.
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