New research is aiming to bring fresher-tasting, additive-free orange juice with a long refrigerated shelf-life to Australian tables.
Food Science Australia, in partnership with US-based Flow International Corporation, is researching the use of high pressure processing (HPP) to kill the food spoilage microbes such as yeast, bacteria and mould that cause off-flavours in aging orange juice.
"HPP involves subjecting the orange juice to intense pressure that causes fatal damage to the outer cell membrane of the microbes," says Jay Sellahewa, project leader at Food Science Australia.
"The pressure causes only minimal damage to the orange juice because the water contained in the juice is relatively incompressible. The microbes are killed leaving a safe product that is free of additives and retains its fresh taste."
HPP is an innovative alternative to thermal-treatment or chemical preservatives, which can sometimes adversely affect the flavour, colour and composition of orange juice. The two-litre HPP unit is manufactured by Flow International Corporation.
The HPP of the orange juice takes place after the juice has been bottled, reducing the risk of contamination after packaging. The bottles of orange juice are subjected to 600 megapascals (MPa) of pressure for 60 seconds.
"In Australia, we have seen escalating consumer demand for safe, fresh, additive-free orange juice. HPP is already being commercialised in the United States, Japan and Europe but this is the first time that the technology has been investigated in Australia," says Mr Sellahewa.
"To reduce the risk of food poisoning, food safety regulatory bodies are increasing demands on processors. Following stricter requirements in the United States, ANZFA (Australian New Zealand Food Authority) has proposed that all orange juice, other than freshly squeezed juice for immediate consumption, is thermally-treated or adequately labelled to inform consumers of risks associated with drinking untreated juice."
The research team from Food Science Australia is comparing the quality of HPP, thermally-treated and fresh orange juice kept over three months in different storage conditions. Sensory panellists taste the orange juice and evaluate its flavour, aroma and appearance. This aims to provide an indication of consumer acceptability of juice and its potential performance in the marketplace.
"The project is a cross-disciplinary team effort, bringing together the experts of Food Science Australia. Our microbiologists give us information about the safety of the orange juice while our analytical scientists tell us about the chemical composition. In addition, we are gathering valuable consumer information from sensory panellists and our engineers are studying the commercial viability of scaling-up the process," says Mr Sellahewa.
Presently, Food Science Australia's Innovative Food Centre is being established. The Centre will continue to research emerging technologies such as HPP and ultrasonics and will include a 35-litre HPP plant.
Food Science Australia is Australia's largest food research organisation, and a joint venture between CSIRO and the Australian Food Industry Science Centre (Afisc).
Flow International Corporation is a US food technology firm with HPP units in operation in the United States, Japan and Europe.