Application of composite cassava starch/chitosan edible coating to extend the shelf life of black mulberries

Abstract

Black mulberry (Morus nigra) is a highly valuable commodity because of its nutritional properties and flavor. However, dehydration and microbial spoilage affect its quality during refrigerated storage. The objectives of this work were to select and apply a composite edible coating to minimize weight losses and microbial spoilage of black mulberries. Optimization indicated that a composite edible coating of chitosan and cassava starch (1:1) was effective for minimizing weight loss and mold decay. This edible coating alleviated weight loss and microbial spoilage of black mulberries stored at 5°C during 16 days. Firmness, color (a* and b*), and anthocyanin content were not significantly (p > .05) affected by this coating during storage. Also, total phenolic compounds and antioxidant capacity remained without major changes during storage. The results allow concluding that a combined edible coating is an interesting alternative to prevent decay and extend shelf life of black mulberries under refrigerated conditions. Practical applications Dehydration and mold decay are the main defects of berries during refrigerated storage. Edible coatings could increase the shelf life of black mulberries and other berries. Cassava starch and chitosan have both relatively low price and high availability, and could be included in the formulation of edible coatings. A composite edible coating based on these compounds could be effective in extending the shelf life of black mulberries stored under refrigerated conditions. All data are available to request.

Multifunctional Role of Chitosan Edible Coatings on Antioxidant Systems in Fruit Crops: A Review

“…It has also been observed that in CS-coated plums a lower increase of anthocyanin content during storage ascribable to the suppression of respiratory activity that allows to slow down the anthocyanin’s synthesis with the decrease in the enzymes activity such as PAL and anthocyanidin synthase (ANS) associated with postharvest ripening [ 56 ]. Contrarily, in other studies have been observed that CS-based coatings improved the anthocyanin content of strawberry, black mulberry, loquat, fig, sweet cherry, pomegranate, and pomegranate arils [ 11 , 45 , 47 , 90 , 94 , 108 , 115 ] suggesting that CS delays fruit senescence and enhances the phytochemicals content during storage. An opposite trend was found by Zam [ 106 ] which report that the dense structure of CS-based coating enriched with olive leaves extract reduced the increase of anthocyanins, probably due to changes in the fruit internal atmosphere during storage compared to uncoated fruits.…”

“…It has been also reported that, the addendum of olive leaves, pomegranate peel, apple peel, stevia extract and cassava starch into CS coating reduced the gradual decline in TP and/or TF in strawberry [ 47 ], guava [ 82 ], litchi [ 105 ], sweet cherry [ 106 ], fresh-cut apple [ 107 ], and black mulberry [ 108 ] during storage. Furthermore, nanostructured CS/propolis coated strawberry fruits exhibited the highest TP content on each day of cold storage [ 109 ].…”

“…Composite cassava starch/CS ECs had no significant effect on phenolic metabolism, without variations on TP content in black mulberry [ 108 ]. Instead, whey protein/CS coating enhanced the TP content in stored strawberry at 5 °C and 20 °C for 8 days [ 110 ].…”

Starch‐Based Coatings for Food Preservation: A Review

“…[ 21,24,26 ] Another disadvantage of this method is related to the possibility of the coating solution diluting other layers of the food surface and degrade its functionality. [ 31 ] This technique has been widely used, mainly for coating of fresh products as Andean blueberries, [ 25 ] eggplants, [ 32 ] cucumbers, [ 33 ] mangoes, [ 34 ] black mulberries, [ 35 ] pomegranate fruit, [ 36 ] mandarins, [ 37 ] and pumpkins, [ 38 ] and to recover and protect chestnuts [ 39 ] and almonds. [ 40 ]…”

“…[21,24,26] Another disadvantage of this method is related to the possibility of the coating solution diluting other layers of the food surface and degrade its functionality. [31] This technique has been widely used, mainly for coating of fresh products as Andean blueberries, [25] eggplants, [32] cucumbers, [33] mangoes, [34] black mulberries, [35] pomegranate fruit, [36] mandarins, [37] and pumpkins, [38] and to recover and protect chestnuts [39] and almonds. [40] The spraying technique is one of the most used processes of coating materials deposition due to the wide possibility of macromolecules used and the great versatility regarding irregular shapes and different sizes (Figure 1d).…”