Adding one gram of chitosan to one litre of fresh orange juice was found to reduce both enzymatic and non-enzymatic browning of the juice, while also controlling the spoilage during the storage time, according to new findings published in Innovative Food Science and Emerging Technologies.
The research taps into an ever-growing body of study exploring novel source of natural alternatives to synthetic preservatives, such as like BHA and butylhydroxytoluene (BHT), to slow down the oxidative deterioration of food is gaining interest.
At present, 'natural' is a powerful force in the food industry, and there is increasing resistance at regulatory and consumer level - as well as from food retailers and manufacturers aiming to meet their demands - to synthetic preservatives.
The study also provides an alternative approach to pasteurization, said the researchers, following concerns raised by the US Food and Drug Administration(FDA) to avoid consumption of un-pasteurised orange juice due to fears of potential contamination with Salmonella Typhimurium.
The researchers, led by Ana Martın-Diana from the Postharvest Technology Unit (PTU) and Functional Ingredient Food Unit (FiFu) at the Dublin Institute of Technology (DIT), enriched orange juice with chitosan in concentrations ranging from 0 to 2 grams per litre of juice.
Addition of chitosan, produced by the deacetylation of chitin - a natural non-digestible polysaccharide found in the cell walls of fungi and the exoskeletons of insects – was found to reduce the counts of bacteria, and reduce the browning of the juice.
However, while chitosan concentrations over 1 gram per litre favourably impacted the quality, they adversely affected the vitamin C content of the juice, as well as increasing the bitterness of the juice, said the researchers.
“The study recommends the use of chitosan at concentrations up to 1 gram per litre to extend quality and preserve ascorbic acid and carotenoids during storage time of fresh orange juice, thus avoiding the use of standard thermal treatments which produce a negative impact on the nutritional value,” wrote Martın-Diana.
Always room for further study
The researchers noted that additional study is required, and should include investigating how the deacetylation degree of chitosan affected the degree of preservation of the juice. Additional microbiological studies should also help clarify the “efficacy of chitosan as a natural preservative for orange juice”, they concluded.
Authors: Innovative Food Science and Emerging Technologies Published online ahead of print, doi: 10.1016/j.ifset.2009.05.003"Orange juices enriched with chitosan: Optimisation for extending the shelf-life, Innovative"Authors: Ana B. Martın-Diana, Daniel Rico, J.M. Barat, Catherine Barry-Ryan