Cooling of freshly cut and freshly harvested fruits and vegetables

 

 

Clément Vigneault,^1* Timothy J Rennie² and Vicky Toussaint¹

¹Agriculture and Agri-Food Canada, 430 Gouin Boulevard, Saint-Jean-sur-Richelieu, Quebec, Canada

²Kemptville Campus – University of Guelph, Kemptville, Ontario, Canada

 

 

 

Abstract

Purpose of review: Fruits and vegetables are well known as being very perishable. The rate of deterioration is highly dependent on the respiration rate, which varies primarily with the type of produce, the temperature and the level of physiological stress. Furthermore, fresh-cut and ready-to-eat horticultural produce generally undergo treatments such as cutting, brushing, washing and peeling; which induce significant physiological stresses while the produce is still alive. These sources of stress and the possibility of pathogen cross-contamination result in produce being highly vulnerable to enhanced deterioration and possible source of food contamination. The most common method of reducing their deterioration rate is by decreasing their internal temperature. There are four cooling techniques used for reducing the temperature of horticultural produce. The purpose of this review is to present these four principles and discuss their advantages and disadvantages for cooling of freshly cut or freshly harvested fruits and vegetables while taking into account the challenge of maintaining the quality of processed produce.

Recent findings: Precooling methods for fruits and vegetables have been studied for many years. However, the recent increase in demand for a wide variety of ready-to-eat meals has placed pressure on the development and presentation of healthy food choices; among which fruits and vegetables hold an important position. As ready-to-eat horticultural produce are often trimmed, washed, brushed, peeled, cored, sliced, shredded and cut, there is an increase in the sensitivity to deterioration due to these stresses, which results in a significant increase of the respiration rate, and to an increased susceptibility to disease.

Directions for future research: Currently many research projects are investigating the efficiency of thermal processes and the uniformity during cooling and heating of horticultural produce. This includes factors such as optimal fluid (air, water and ice) distribution, fluid flow rate, package opening shape and distribution. Despite these attempts, there remains a significant lack of information on the needs and requirements for thermal processes involving fresh-cut or ready-to-eat horticultural produce. These two types of produce (fresh and ready-to-eat) are often treated as the same; however, they are biologically very different. New research projects on thermal processing of fresh-cut produce are highly desirable. From the model development point of view, the engineering aspect of cooling and heating of freshly harvested and ready-to-eat horticultural produce differ only on size and heat transfer direction. However, they are completely different on the biological aspect. More research is required considering this important difference.

 

Keywords: Ready-to-eat; fresh-cut; forced air cooling; hydrocooling; liquid ice; vacuum cooling; precooling; food safety; quality

 

Stewart Postharvest Review 2008, 3:4

Published online 01 June 2008

doi: 10.2212/spr.2008.3.4