EFFECTS OF LOW DOSE GAMMA IRRADIATION ON HIGHBUSH BLUEBERRY FRUIT QUALITY AND PROXIMATE AND NUTRITIONAL PROFILES

Blueberry (Vaccinium corymbosum, Northern Highbush, ‘Brigitta’) fruit were subject to gamma irradiation (0, 150, 400 and 1000 Gy) at the Australian Nuclear Science and Technology Organisation. The experimental design was a split plot design with three replicates of four irradiation treatments and two storage times. After treatment, fruit were stored at 0°C for three or ten days before assessment of fruit quality and proximate and nutritional analysis. The dosimetry of the irradiation treatment was excellent with high levels of precision and accuracy. Results showed that irradiation at any dose (≤1000 Gy) did not affect blueberry quality (overall fruit quality, colour, firmness (subjective and objective measures), shrivel, weight loss, TSS, TA levels, TSS/TA ratio and juice pH), or the nutritional or proximate contents (contents of ash, carbohydrate, dietary fibre, energy, moisture, protein, sodium, potassium, total sugars, fructose, ascorbic acid, anthocyanin, citric and malic acids) of treated fruit which had been stored for either three or ten days. As expected, the length of time in storage affected some fruit quality parameters and nutritional and proximate contents (overall fruit quality, firmness, weight loss, TA levels and juice pH, carbohydrate, dietary fibre, energy, protein, potassium, total sugars, glucose, ascorbic acid, citric and malic acids), with longer storage periods resulting in lower quality fruit, irrespective of irradiation. However, the overall fruit quality over the entire trial was good. There was no interaction between irradiation treatment and storage time, indicating that irradiation did not affect the quality characteristics of blueberry fruit.