Abstract
Color change of fruit-based products during storage is an important quality parameter to determine their shelf life. In this study, a combination of relative humidity (RH) and illumination was evaluated on the stability of strawberry leathers. Samples were conditioned at 25 °C, in chambers with RH of 22.5% and 52.3% and under two levels of illumination (no illumination and with a light-emitting diode (LED) illumination at 1010 lx). Samples were analyzed during storage by instrumental color measurements, total anthocyanin content, and consumers’ acceptance/rejection of the product color. Current-status survival analysis was performed to estimate the sensory-based shelf-life of the strawberry leather. The chromatic parameters (a* and ΔE* values) and anthocyanin content changed with increasing storage time and RH, fitting a first-order fractional conversion model. Samples conditioned at the higher RH showed a higher reduction of a* values and anthocyanins losses when stored under LED illumination than those without illumination. The increase of RH resulted in a faster increase of the consumer rejection probability and a shorter shelf life of the strawberry leather. For 50% of consumers’ rejection, the sensory shelf life of the strawberry leather equilibrated at 22.5% RH was estimated as at least 54 days, while it was reduced to approximately 2 days at 52.3% RH. The red chromatic parameter (a* value) strongly correlated to the percentage of consumer rejection in all storage conditions, suggesting that this analytical parameter can be useful as a predictor of strawberry leather’s shelf life. Therefore, the results of this study show the applicability of an approach that integrates instrumental and sensory data to acquire faster information on color changes during the storage of strawberry leather and product shelf-life prediction.
Highlights
Fruit leather, known as fruit bar or restructured fruit, is a product in the form of a pliable strip or sheet obtained by thin-layer drying of fruit pulp, with or without the incorporation of additives
Samples before storage showed an a* value of 37.81 ± 2.13, and after 90 days at 22.5% relative humidity (RH), this value decreased to 30.93 ± 1.76 and 31.08 ± 1.08, without and with illumination, respectively, while samples conditioned at 52.3% RH after 21 days showed an a* value of 22.74 ± 0.56 and 17.26 ± 0.67, without and with illumination, respectively
This result could be related to the anthocyanin degradation and non-enzymatic browning reactions, which are accelerated at higher water activities [37]
Summary
Known as fruit bar or restructured fruit, is a product in the form of a pliable strip or sheet obtained by thin-layer drying of fruit pulp, with or without the incorporation of additives. It is an alternative to preserving, adding value and diversifying consumption options of various fruits. This product is a typical healthy snack in North America, Africa, and Asia. The relatively low moisture content, intermediate water activity, and low pH value of fruit leather result in microbiological stability of the product for up to 6 months [1]. The shelf life of fruit leathers and many food products is stated by altering their sensory aspect before their microbiological safety is compromised [2]. According to Buvé et al [3], the color change during storage is the main parameter that predicts the shelf life of fruit-based products
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