The team, led by Dr Candice Smarrito of the Nestlé Research Centre in Lausanne, examined the effects of low pressure – such as that found at high altitude – on the sensory profile of vegetable broth. They found flavours and vegetable yields were enhanced at lower pressure, creating a richer broth without additives.
The researchers said the effect could be explained by the lower boiling point of water at high altitude and lower pressure – water boils at just 85°C at 3,600m above sea level, for example, allowing foods to cook more gently and preserving their volatile compounds, such as aromas.
“Flavour is a key driver of food acceptance and consumer preference,” Smarrito said. “So we prepared vegetable broths consisting of exactly the same quantities of turnip, carrot, leek and celeriac cooked at high, low and ambient pressure.
“The results were then analysed both in the laboratory using a range of analytical processes, and by a panel of tasting experts to see how the different combinations of pressures and cooking times impacted on the culinary quality and molecular and sensory profile of the preparations.”
Nestlé said the research was part of ongoing work to enhance the flavour, appearance and nutrition of food without using artificial additives and enhancers.
The study said there were two different ways to cook at low pressure without travelling to high altitudes: Sous-vide, which involves vacuum sealing the food in plastic pouches and immersing them in a water bath at 65-85°C, and cook-vide, in which pressure is reduced and controlled by a vacuum pump.
“Cooking in such conditions has been shown to prevent losses of aroma compounds and moisture, leading to food preparations with enhanced juiciness and flavour intensity,” Smarrito and her colleagues wrote.
They found that sulphur aromas associated with leeks were particularly enhanced by low pressure cooking.
“Low-pressure cooking could be advantageously used to improve the nonvolatile and volatile composition as well as the sensory profiles of broths (especially regarding the overall intensity, leek/onion, and celery/savoury notes),” they wrote. “…Thus, low-pressure boiling might apply to enhance the flavour profiles of culinary preparations and therefore could help to increase consumer preference.”
The researchers added that this effect may also extend to preservation of vitamins and minerals, although further study was needed.
Source: Journal of Agricultural and Food Chemistry
Published online ahead of print. DOI: 10.1021/jf506173m
“Impact of Boiling Conditions on the Molecular and Sensory Profile of a Vegetable Broth”
Authors: Alice Mougin, Olivier Mauroux, Walter Matthey-Doret, Eugenia Maria Barcos, Fernand Beaud, Ahmed Bousbaine, Florian Viton, and Candice Smarrito-Menozzi