The study was conducted by the Sher-e-Bangla Agricultural University Laboratory in Dhaka, Bangladesh between May and July 2017.
3 Experimental materials The experimental materials were matured fruits of litchi variety, namely, Bedana. Litchi fruits were harvested at full red colour stage from the orchard of Mashimpur, Dinajpur, Bangladesh in May 2017. Maturity of the fruit is indicated by the red colour and fruit size more or less similar. Besides colour, the maturity of the fruit is indicated when tubercles become somewhat flattened and the covers become smooth. Maturity was also judged by the grower’s recommendation. The fruits were then processed after shipment in the laboratory. Then, the fruits were subjected to different bio preservatives as treatment.
4 Treatment and design of the experiment The study was carried out with three replications of completely randomised design (CRD). There were six treatments and three replications in each treatment.
5.1 Control (T0) The selected fresh Litchi fruits were divided into four parts, every part remain ten fruits with three replications. One part remains with packaging at ambient condition, and one part remains without packaging at ambient condition.
5.2 CaCl2 dips fruits preserved without packaged and packaged with perforated LDPE bag under ambient temperature (T1) The selected fresh Litchi fruits dipped in CaCl2 for 10 minutes within 2 h of harvesting and then air-dried. Then the fruits were divided into four parts, every part remain ten fruits with three replications. One part remains with packaging at ambient condition, and one part remains without packaging at ambient condition.
5.3 Oxalic acid and bavistin treated fruits preserved without packaged and packaged with perforated LDPE bag under ambient temperature (T2) The selected 120 fruits were dipped in oxalic acid solutions (2 mM oxalic acid + 0.05% fungicide, Bavistin) for 10 min within 2 h of harvesting and then air-dried. Then the fruits were divided into four parts each part contains 30 fruits (with replications). Then the fruits were divided into four parts, every part remain ten fruits with three replications. One part remains with packaging and one part remains without packaging at ambient condition.
5.4 Ice treated fruits preserved without packaged and packaged with perforated LDPE bag under ambient temperature (T3) Hydro cooling of selected fruits was achieved by dipping the fruits in a water bath with stainless steel at 0°C–1°C for 15 minutes until the core pulp temperature reached 5°C. Using a thermometer, the core pulp temperature was controlled. Until packing, the hydro chilled fruit was dried by air via an electric fan. Then the fruits were divided into four parts, every part remain ten fruits with three replications. One part remains with packaging at ambient condition and one part remains without packaging at ambient condition.
5.5 Ice + oxalic acid + bavistin treated fruits preserved without packaged and packaged with perforated LDPE bag under ambient temperature (T4) The fruit was hydraulically cooled at 0°C–1°C during 15 minutes before core pulp temperature reached 5°C. In the case of a fruit, the fruit was immersed in a bath of stainless steel. Using a thermometer, the core pulp temperature was monitored. The fruit was then dried air with a hydro-cooled fan then deeper into 2 mM oxalic acid with 0.05% fungicide (bavistin) solution for 10 minutes and then air dried using an electric fan. Then the fruits were divided into four parts, every part remain ten fruits with three replications. One part remains with packaging at ambient condition and one part remains without packaging at ambient condition.
5.6 Ice + oxalic acid treated fruits preserved without packaged and packaged with perforated LDPE bag under ambient temperature (T5) Hydro-cooling of selected fruits was achieved by dipping the fruits in a water bath with stainless steel at 0°C–1°C for 15 minutes until the core pulp temperature reached 5°C. Temperature of the core pulp was tracked with a thermometer. The hydro-cooled fruit was then air-dried with an electric ventilator then dipped into 2 mM oxalic acid solution for 10 minutes and then air dried using an electric fan. Then the fruits were divided into four parts, every part remain ten fruits with three replications. One part remains without packaging at ambient condition and one part remains with packaging at ambient condition. 5.7 Wash with clean water (T6) The selected 120 fruits were washed with clean water for 15 min, then the hydro washed fruits were air dried using an electric fan prior using postharvest treatments.