Termodinamica

Journal of Food Engineering 45 (2000) 55±65

www.elsevier.com/locate/jfoodeng

Vacuum cooling technology for the food processing industry: a review
Karl McDonald, Da-Wen Sun *
FRCFT Group, Department of Agricultural and Food Engineering, University College Dublin, National University of Ireland, Earlsfort Terrace, Dublin 2, Ireland Received 28 October 1999; accepted 31 January 2000Abstract Vacuum cooling is a rapid evaporative cooling technique, which can be applied to speci®c foods and in particular vegetables. Increased competitiveness together with greater concerns about product safety and quality has encouraged some food manufacturers to use vacuum cooling technology. The advantages of vacuum cooling include shorter processing times, consequent energy savings, improvedproduct shelf life, quality and safety. However, the cooling technique has a limited range of application. Traditionally, products such as lettuce and mushrooms have been cooled under vacuum. Recent research has highlighted the possible applications of vacuum cooling for cooling meat and bakery products, fruits and vegetables. This paper comprehensively reviews the current state of the technology. Itis concluded that while vacuum cooling remains a highly specialised cooling technique, with continuing research its application may make its use in the food and vegetable processing industries more competitive and widespread. Ó 2000 Elsevier Science Ltd. All rights reserved.
Keywords: Vacuum cooling; Rapid cooling; Chilling; Refrigeration; Foods; Vegetables; Meats; Ready meals

Contents 1. 2.Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Applications of vacuum cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1. Fruit and vegetables . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2. Meat and meat products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3. Fish and ®sh products. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 2.4. Sauces, soups and particulate foods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5. Bakery products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6. Ready meals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 57 58 59 59 59 60

3. 4. 5.

Advantages and disadvantages of vacuum cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Factors a€ecting vacuum cooling rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 62 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

1. IntroductionVacuum cooling is a batch process whereby moist products containing free water are cooled by evaporaCorresponding author. Tel.: +353-1-706-7493; fax: +353-1-4752119. E-mail address: dawen.sun@ucd.ie (D.-W. Sun).
*

tion of moisture under vacuum (Mellor, 1980). Products to be cooled are loaded into a vacuum chamber and the system put into operation (Anon, 1994) as shown in Fig. 1. The vacuum...