Drying of food products under inert environment

 

 

MNA Hawlader^1* and Mya Mya Khin²

¹Department of Mechanical Engineering, National University of Singapore, Engineering Drive, Singapore

²Department of Chemistry, Food Science & Technology Programme, Science Drive, Singapore

 

 

 

Abstract

Purpose of review: Heat pump drying of food products under inert environment provides an opportunity to retain quality in terms of colour, flavour and nutrients. This system enables independent control of the temperature and relative humidity of the drying medium, which is considered essential for heat sensitive food products. The absence of oxygen from the drying media prevents oxidation of food products during drying and, as such, no browning occurs. This article reviews the status of research on drying under inert environment (where the drying medium is nitrogen gas or carbon dioxide) and the impact of inert atmosphere on drying parameters such as drying rate, mass transfer coefficient, heat transfer coefficient and quality of the product.

Findings: Although several drying methods have been used extensively to fulfil the demand for long shelf-life of food products, each drying method has certain limits that can affect the drying rate and the quality of food products in terms of colour, flavour and nutrient retention. In recent years, several studies have been carried out using inert atmosphere, particularly in heat pump dryers. Applications of inert atmosphere are increasing for drying food products in order to yield better quality products.

Directions for future research: More studies are needed to cover a wider spectrum of heat sensitive food products.

 

Keywords: Heat pump drying; inert environment; heat sensitive materials; quality retention; low temperature applications

 

Stewart Postharvest Review 2008, 1:3

Published online 01 February 2008

doi: 10.2212/spr.2008.1.3