The impact of two‐sided ultraviolet radiation and long‐term freezing on quality of date fruit at rutab stage

Abstract

Pre-packed rutab date fruit in polypropylene containers were exposed to long-term freezing and two-sided UV-C radiation. During 42 days shelf life, the microbial load of long-term frozen samples which were UV radiated, was 2.4–2.6 compared to 3.1 log CFU/g of control. This treatment combination also slowed down the rate of surface browning and flesh darkening as the basic quality attribute of rutab date for consumer perception. Against fruit Total soluble solids (TSS) that did not fallow a certain trend, fruit acidity increased by 3.7–5.9 times (from 8.1 mg/100 g). Total phenolic content (TPC) dropped gradually from the initial value of 1,247 mg GA/Kg FW and after 30 days, the loss in TPC for control samples was almost two times of those fruits that received both freezing and UV treatments. Totally, best quality of rutab date in terms of appearance, taste, and nutritional value were recorded in fruits that received both freezing and UV-C radiation. Practical applications For many consumers, rutab stage is considered as the most delicious and popular form of date fruit. The main properties of rutab date, that is, having high level of sugar and water content, makes it very vulnerable to microbial contamination. On the other side, the fruit soft texture makes it difficult to be washed or disinfected. The results of this work reveals that the conventional freezers can be used as an available and effective method of keeping rutab fruit quality for long term. Even though the antimicrobial effects of UV radiation have been reported frequently, but the used apparatus for applying UV radiation from both sides on the pre-packed fruits can be easily redesigned to equip the commercial packing lines of date fruit.