Ready-to-use broccoli raab (Brassica rapa L. subsp. sylvestris) quality and volatilome as affected by packaging

Abstract

Broccoli raab (Brassica rapa L.) is a cruciferous vegetable primarily grown in the southern regions of Italy. Distinguished from the more common broccoli head (B. oleracea), its edible parts consist of sprouts, buds, younger stems, and leaves. Considering the high perishability of broccoli raab, it is necessary to apply postharvest technologies to make it a ready-to-use product. In this paper, active modified atmosphere packaging (aMAP, closed at 3% O2 and 97% N2) was applied, in combination with two types of packaging materials (polypropylene/polyamide microperforated, PP/PA MF, and polypropylene, PP). Shrink-wrap packaging and air-storage were included as control measures. The purpose was to assess the effects of different packaging conditions on enhancing knowledge about volatile compound development and quality aspects of the produce. Both packaging materials resulted in a 10% accumulation of CO2, combined with 1% O2 for PP bags and 10% for PP/PA. Different gas mixtures led to varied sensory and volatile development in minimally processed broccoli raab during storage. PP exhibited the lowest odor score (1.2, well below the marketability limit) and the highest concentrations of off-odor-related volatile compounds (ethanol, acetaldehyde, dimethyldisulfide, dimethyltrisulfide, and methanethiol) while samples packed in PP/PA MF reached an intermediate odor score with superior visual quality evaluation up to 12 days of storage. Both packaging materials reduced weight loss compared to control samples, up to less than 2% and 6%, respectively. In conclusion, active MAP using PP/PA MF bags demonstrated the best suitability in maintaining broccoli raab quality, with a final gaseous composition of 10% O2 and 12% CO2 deemed optimal for storage.