Longer life for festive sweets
The shelf life of coconut burfi could be increased to 75 days thanks to a combination of thermal processing and existing packaging materials.
Microbial spoilage is a key factor in reducing the shelf life of the South Indian sweet, due to the high percentage of saturated fat that makes it prone to hydrolytic rancidity, browning, drying crystallisation and mould growth.
Lead Researcher Ambuga R. Indiramma, at the Central Food Technological Research Institute in Mysore, India, says, ‘Except on dehydrated foliage, soft foliage and desiccated coconut, there is not much literature on the packaging of traditional sweets...Even with a sugar content of 55%, coconut burfi like any other sweet, undergoes microbial spoilage due to its high water activity (Aw) of about 0.83. The increase in free fatty acid content, coupled with mould growth, limits the shelf life [of coconut burfi] to 7-10 days in unpacked conditions.’
To combat this, the team has tested samples of the sweet packed in flexible multilayer film pouches of 130x60mm, consisting of polyester/polyethylene (PET/PE) and polyester/aluminum foil/ polypropylene (PET/AI/PP). The packaging materials have been trialled under three conditions – normal packing, 99% vacuum packaging and in-package heat processing. The pouches with 40-50g of product were packed without any removal of headspace air and were subjected to thermal processing at 95ºC in a steam retort for 25 minutes and stored at 27ºC and 65% relative humidity. Then were periodically withdrawn to monitor changes in chemical, microbiological and sensory qualities.
According to Indiramma, controlled moisture and oxygen was achieved, delaying microbial spoilage. Furthermore, the PET/AI/PP and PET/PE revealed similar shelf life results, <15 days in air packed conditions, 45 days in vacuum and 75 days in heat processed conditions.
Alan Moffat, Packaging Development Manager at Heinz, headquartered in the USA, comments, ‘Reading the full transcript, the overall protocol is acceptable and the choice of materials for the packaging is sound. However, there is a major reservation – the superior barrier properties of the PET/AI/PE pack should have given a different result to the PET/PE material.
‘My conclusion from the results are that there was a fundamental flaw either in the steam retort processing or in the seal/barrier integrity of the pouch and whilst not being a processing expert, I would suggest the flaw lies in the processing.’
The most conclusive result, Indiaramma argues, was the PET/PE sample. She adds, ‘Shelf life which was less than 15 days when unprocessed and air packed was extended to 75 days by heat processing. It [PET] is also the cheapest material and withstands the thermal processing conditions. However, it is not the packaging material alone that can extend the shelf life, but the hurdle technology of packaging and thermal treatment.’
The research group also sees potential applications for the technique in further indian sweets packaging, such as Laddu and similar confectionary with a Aw of 0.8.
Packaging Professional Magazine, 20 Sep 2010
Microbial spoilage is a key factor in reducing the shelf life of the South Indian sweet, due to the high percentage of saturated fat that makes it prone to hydrolytic rancidity, browning, drying crystallisation and mould growth.
Lead Researcher Ambuga R. Indiramma, at the Central Food Technological Research Institute in Mysore, India, says, ‘Except on dehydrated foliage, soft foliage and desiccated coconut, there is not much literature on the packaging of traditional sweets...Even with a sugar content of 55%, coconut burfi like any other sweet, undergoes microbial spoilage due to its high water activity (Aw) of about 0.83. The increase in free fatty acid content, coupled with mould growth, limits the shelf life [of coconut burfi] to 7-10 days in unpacked conditions.’
To combat this, the team has tested samples of the sweet packed in flexible multilayer film pouches of 130x60mm, consisting of polyester/polyethylene (PET/PE) and polyester/aluminum foil/ polypropylene (PET/AI/PP). The packaging materials have been trialled under three conditions – normal packing, 99% vacuum packaging and in-package heat processing. The pouches with 40-50g of product were packed without any removal of headspace air and were subjected to thermal processing at 95ºC in a steam retort for 25 minutes and stored at 27ºC and 65% relative humidity. Then were periodically withdrawn to monitor changes in chemical, microbiological and sensory qualities.
According to Indiramma, controlled moisture and oxygen was achieved, delaying microbial spoilage. Furthermore, the PET/AI/PP and PET/PE revealed similar shelf life results, <15 days in air packed conditions, 45 days in vacuum and 75 days in heat processed conditions.
Alan Moffat, Packaging Development Manager at Heinz, headquartered in the USA, comments, ‘Reading the full transcript, the overall protocol is acceptable and the choice of materials for the packaging is sound. However, there is a major reservation – the superior barrier properties of the PET/AI/PE pack should have given a different result to the PET/PE material.
‘My conclusion from the results are that there was a fundamental flaw either in the steam retort processing or in the seal/barrier integrity of the pouch and whilst not being a processing expert, I would suggest the flaw lies in the processing.’
The most conclusive result, Indiaramma argues, was the PET/PE sample. She adds, ‘Shelf life which was less than 15 days when unprocessed and air packed was extended to 75 days by heat processing. It [PET] is also the cheapest material and withstands the thermal processing conditions. However, it is not the packaging material alone that can extend the shelf life, but the hurdle technology of packaging and thermal treatment.’
The research group also sees potential applications for the technique in further indian sweets packaging, such as Laddu and similar confectionary with a Aw of 0.8.
Packaging Professional Magazine, 20 Sep 2010
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