Plastic film packaging for the postharvest quality of fresh hop inflorescence (Humulus lupulus) cv. Cascade

Abstract

Hop is an essential raw material for beer production, but, after harvest, the inflorescences have a very short shelf life. For this reason, the aim of this research was to study the effect of 4 different plastic films packaging on quality and shelf-life of fresh hops inflorescence. LDPE (low density polyethylene), LP280 (low density polyethylene-metallocene low density polyethylene-ethylene vinylic alcohol), MF (microperforated low density polyethylene-linear low density polyethylene) and HDPE (high density polyethylene-metallocene low density) plastic films, after a week of a great reduction in O2 and increase of CO2, were able to maintain O2 between 4 and 12 kPa and CO2 between 10 and 18 kPa during 28 d of storage at 3 °C. In these atmospheres, hop inflorescence chlorophyll decreased less than in MF film as well as α-acid and β-acid, while carotenoids increased but without significant difference among plastic films. MF did not produce any atmosphere different from the air but, in the 1st week, limited the negative effect (reduction of polyphenols and antioxidant properties) of atmosphere stress condition (very low O2 and high CO2), due to the high inflorescence respiration inside the low and very low permeability plastic films. Thus, to store hop inflorescences for one week, MF film is sufficient but, for a longer period, the atmosphere created by LDPE, LP280, and HDPE films, could be a good solution, before processing.