Making the international national: scientists aim to lock in aromas of exported foods

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  • Published: Oct 1, 2016
  • Author: Ryan De Vooght-Johnson
  • Channels: Gas Chromatography
thumbnail image: Making the international national: scientists aim to lock in aromas of exported foods

Cultural crash course

Amidst the hustle bustle of the Twenty-First Century, many of us are tapping into cuisines from far-flung cultures. But, having traversed the high seas, how do they retain their flavours?

If the modern world is a cooking pot, it is to globalisation that we owe our thanks for our flavours. Increasingly interconnected with our ancestors who diverged and developed independently from us since Homo sapiens first ventured out of Africa, we are now able to take a crash course in cultures we have missed out on for generations. A cultural catch-up, in effect.

Take foreign cuisines, for example. Long gone are the times when our geographical location dictated what we wolfed down. Through global trade routes and a universal economic model, we can now tickle our taste buds with recipes and ingredients perfected half-the-world-away in our very homes. But, having traversed the high seas for days on end, how do foreign foods still appetise? Through rigorous chemical testing, it turns out.

Dr Leelaphiwat is a chemist at Kasetsart University in Thailand, who, together with collaborators worldwide, aimed to test how three packaging materials would seal in the chemicals responsible for the appetizing aroma and tastes of Thai tom yam seasoning bought off Bangkok’s shelves.

Sniffing around

Industry has long known the importance of aromatic compounds—and carbon-based compounds in particular—to the overall organoleptic experience. These, however, are absorbed by and waft through their protective packaging, weakening both their aroma and taste.

‘Aroma loss occurs due to the interactions between aroma compounds and polymeric packaging materials,’ Leelaphiwat writes in the Journal of the Science of Food and Agriculture. ‘Thus the aroma barrier is an important characteristic of packaging materials in protecting against aroma loss.’

To test the effectiveness of frequently used packages, Leelaphiwat sealed 30 g of tom yam powder with Nylon 6, polyethylene terephthalate (PET) or polylactic acid (PLA) membranes. She then stored these powders for up to 49 days at 38 °C—to speed-up the food spoiling process—and then put these through both taste and chemical analyses.

Vials of samples were first shipped over to the sensory research facility based at the Michigan State University in the USA. Here, six highly sensory and trained panellists—whittled down from 20 through vigorous sensory testing—scored the intensities of the definitive aromas associated with tom yam: the ‘lemongrassyness’ of lemongrass, the ‘acidity’ of galangal, and the ‘leafiness’ of kaffir lime leaf. The panellists tended to score the samples stored away for longer as less intense in their aroma. What’s more, the same panellists did not notice a change in this deterioration according to the material they were sealed in.

Chemical confirmation

Elsewhere, the air in the store-away vials was analysed by GC-MS, after which the aromatic compounds were identified from a mass spectral library and their abundances were quantitated.

This chemical analysis first identified the major components of tom yam—estragole, bicycle[3.1.1]heptane, β-bisabolene, benzoic acid, and 2-ethylhexyl salicylate. Secondly, it showed how the abundance of these compounds deteriorated over time. Thirdly, that the packaging polymer did not affect this deterioration in the slightest.

‘Sensory evaluation and GC-MS analysis,’ Leelaphiwat and colleagues concluded, ‘can be combined with the permeability values determined from sorption experiments to predict the aroma loss through packaging materials during storage.’

Related Links

Journal of the Science of Food and Agriculture, 2016, Early View paper. Leelaphiwat et al. Effects of packaging materials on the aroma stability of Thai ‘tom yam’ seasoning powder as determined by descriptive sensory analysis and gas chromatography–mass spectrometry.

Article by Ryan De Vooght-Johnson

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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