Content of saccharides, antioxidant and sensory properties of pear cultivar "Abate Fete" affected by ultrasound pre-treatment and air drying duration

The effect of ultrasound pre-treatment on quality attributes of air-dried pears was investigated, with the aim of shortening the overall processing time, maximizing the production yield and maintaining the optimum contents of saccharides and bioactive compounds. The contents of saccharides, total phenols and flavonoids, as well as the antioxidant capacity were determined spectrophotometrically. Consumer evaluation of sensory properties was conducted using hedonic scale preference analysis. Under the same air-drying conditions, prolonged ultrasound pre-treatment led to a decrease in the contents of total saccharides, phenols and flavonoids, as well as to a decrease in antioxidant capacity and sensory quality (appearance of brown spots, grainy mouth feel, hard texture) of dried pears. The highest contents of fructose, glucose and saccharose amounted to 381.95 mg center dot kg(-1), 279.81 mg center dot kg(-1) and 28.52 mg center dot kg(-1) of dry matter of sample, respectively, while non-treated pears dried for 720 min exhibited the highest total phenol content of 4.33 g center dot kg(-1) of dry matter (expressed as gallic acid equivalent). According to the performed experiments, the combination of a shorter ultrasound pre-treatment (up to 10 min) and 360 min of air drying is the most efficient for obtaining a product with the best nutritive composition, in terms of saccharide and polyphenol contents, as well as the best sensory properties.