The authors, in findings published in the International Journal of Food Science and Technology, found that high shelf life value of pasta packed in a high barrier PET, EVOH and PE based multilayer film under MAP for over 17 is a result of the film’s ability to maintain the initial modified headspace conditions during the entire storage period.
Due to the increasing consumer demand for high quality food that does not rely on the use of chemical additives for preservation, scientific researchers have been focusing on methods of shelf life extension for perishable foods using modified atmosphere packaging (MAP) or natural compounds with antimicrobial properties such as chitosan.
The authors said their goal was to evaluate the influence of the natural compound, MAP and film packaging on shelf life extension of durum semolina-based fresh pasta, made by a pilot plant.
They said they tested three different concentrations of chitosan and two packaging films with high and low barrier properties to assess their influence on the microbiological and sensorial quality of fresh pasta.
The main spoilage microbial groups for fresh pasta include mesophilic and psychrotrophic bacteria, total coliforms, Staphylococcus spp., lactic acid bacteria, as well as yeasts and moulds.
The research team explained that fresh pasta samples were produced by using durum semolina, with chitosan dissolved in lactic acid added to the dough at three different concentrations: 1000, 2000 and 3000 mg kg−1.
As a control, they continued, pasta samples without the antimicrobial compound were also prepared, and no lactic acid was added to the control sample.
The authors said that about 200 g of pasta samples were arranged in a plastic tray, which in turn was packaged in a plastic bag, with two polymeric films with different characteristics used as packaging bags.
These bags, they reported, included an anti-fog low-barrier film (Low-B), made up of polypropylene (PP) with 30 μm thickness and an anti-fog high-barrier multilayer film (High-B) made up of polyethylene terephthalate (PET), ethylene-vinyl alcohol (EVOH) and polyethylene (PE), with 90 μm thickness.
The researchers said that all packaged samples were sealed by means of a thermal sealer under ordinary atmosphere (passive MAP, named as P-MAP) and modified atmospheric conditions (active MAP, named as A-MAP).
They added that in order to realise the modified headspace conditions gas concentrations of 70 per cent CO2 and 30 per cent N2 were used, with all the samples then stored at 4°C.
The results, said the researchers, indicate that MAP, higher barrier film and chitosan can act in synergic way in terms of microbial acceptability limit (MAL) of fresh pasta.
“Higher MAL values were obtained for samples packaged in High-B film under A-MAP. In particular, for these samples visible moulds did not occur, whereas for the other samples visible moulds were detected at the tenth day storage,” they found.
The scientists said that microbial growth in samples packaged in Low-B under P-MAP and A-MAP, and in High-B under P-MAP was favoured by the presence of oxygen, which generally promotes the growth of aerobic microorganisms:
“The oxygen was naturally present in the P-MAP and gradually increased in the headspace of Low-B bag sealed under A-MAP, due to the scarce film barrier properties.”
They found that chitosan efficiently delayed the growth of mesophilic bacteria in pasta packaged in both films under P-MAP and A-MAP, when compared to the control, with the results confirming the well-known antimicrobial properties of chitosan on Gram positive and negative bacteria.
They said that the MAL value for the pasta dough with chitosan 3000 mg kg−1 concentration and packaged in High-B under A-MAP was 21.51 days compared to the control. And the team said that the samples employing chitosan concentrations of 1,000 and 2,000 mg kg−1 showed lower MAL values (11.70 and 10.51 days, respectively).
The researchers also note that their study suggests that the sensorial quality, in particular the odour of the packaged product, plays a significant role in determining product acceptability.
Source: International Journal of Food Science and Technology
Published online ahead of print: DOI: 10.1111/j.1365-2621.2010.02277.x
Title: Shelf life extension of durum semolina-based fresh pasta
Authors: C. Costa, A. Lucera, M. Mastromatteo, A. Conte, M. Alessandro Del Nobile