Investigating the impacts of harvest stages, citric acid and calcium lactate treatments on changes in quality attributes and natural microbiota of minimally processed litchi during storage

Abstract

The study investigated the changes in quality of minimally processed litchi arils, harvested at two different dates (H) and treated with citric acid (1%, T1), calcium lactate (1%, T2), and citric acid (1%) + calcium lactate (1%) (T3) for 2 min. Treated litchi arils and non-treated (control) were packed in punnets and stored at 1°C for 12 days and sampled every 3 days. To simulate consumer shelf life conditions, at each sampling day, additional samples were transferred to 10°C and stored for 2 days. The interaction effects of harvest dates, postharvest treatments, and storage duration significantly influenced TA, PH, radical scavenging activity, and ascorbic acid content of the litchi arils (p < .05). At the end of storage, litchi arils harvested early and treated with T3 presented higher radical scavenging activity (36.6 mmol AAE/ml). In contrast, fruit harvested late and treated with T3 had higher ascorbic acid content (72.9 μg/ml) at the end of the storage. Browning was significantly reduced in litchi arils harvested early and treated with T3 (−534.5) at the end of storage. The natural fungal profile on litchi arils was influenced by harvest date, pre-treatments, cold storage, and duration. Colletotrichum gloeosporroides was found to be the most dominant, followed by Phomopsis sophorae in early-harvested litchi arils before storage. However, Diaporthe sp. were found to be the most dominant during cold storage. For the late harvest litchi arils, Chaetomium sp., and Trametes polyzona were observed to be dominant. Practical applications The greatest postharvest limitation to litchi fruit is pericarp browning, which causes consumers rejection in the market while the edible portion is still in excellent condition. Following the rejection of sulfur dioxide fumigation as a method of pericarp browning control, minimal processing of litchi fruit at different harvest stages and pre-treated with organic acids (citric acid, calcium lactate, and their combination) was carried out. The findings from the study showed that minimally processed litchi arils treated with citric acid alone or combined with calcium lactate could potentially maintain its freshness.