High pressure processing of swede (Brassica napus): Impact on quality properties

The effects of combined pressure/temperature treatments (200, 400 and 600 MPa, at 20 and 40 °C) on the physical and nutritional properties of swede roots (Brassica napus var. napobrassica) were assessed. Changes induced by high pressure processing (HPP) on the original properties of swede samples were compared with those produced by thermal treatment (blanching). All studied treatments altered the physical properties of swede, resulting in a loss of hardness and water binding capacity. The strongest alteration of texture was observed after HPP at 400 MPa, while 600 MPa was the treatment that better preserved the texture properties of swede. Blanching caused less total colour changes (ΔE) than HPP. Antioxidant properties of swede were measured as total antioxidant capacity, ascorbic acid and total phenol content. All treatments caused a loss of antioxidant capacity, which was less pronounced after HPP at 600 MPa and 20 °C and blanching. Four glucosinolates were detected in swede roots, glucoraphanin, progoitrin, glucobrassicanapin and glucobrassicin. Glucobrassicanapin and glucobrassicin contents were reduced with all studied treatments. Progoitrin content was not affected by blanching and HPP at 200 MPa. HPP at higher pressure levels (400 and 600 MPa), though, induced an increase of progoitrin levels. The results indicated that blanching and HPP at 600 MPa and 20 °C were the treatments that better preserved the original quality properties of swede.Industrial relevanceDevelopment of mild processing technologies that minimally affect the sensory and texture of products is a challenge for the food industry. The present work has studied the effects of combined pressure–temperature treatments on the colour, texture, antioxidant activity and glucosinolate profile of fresh-cut swede (Brassica napus) as an alternative to traditional blanching techniques.

Research Highlights
► Pressurisation of swede at 600 MPa produced the lowest lost of original texture.
► Pressurisation produced a higher colour change than mild heat treatment in swede.
► Pressurisation at 600 MPa/20 ºC produced the lowest loss of antioxidant properties.
► The glucosinolate content varied in function of treatment and glucosinolate studied.