Preservation of the sensory quality of fresh and frozen vegetables under different storage conditions

A. Maaßen, H. F. Erbersdobler, M. Busch-Stockfisch, Hamburg / Kiel

Shelf life is an important aspect of the quality assessment of vegetables. The present article is answering the question as to how far the sensory quality of certain fresh and frozen vegetables changes under different storage conditions. The influence of freezing on the sensory properties of green peas, green beans, carrots, Brussels sprouts and spinach was investigated.

The vegetables were investigated by trained assessors using the method of “Konventionelle Profilprüfung” who created typical sensory profiles. The vegetables were also characterizised by a consumer panel by the method of free choice profiling. To connect the professional profiles with the liking data of the consumer panel the Preference Mapping method was used.

The vegetables studied responded very differently to storage. For peas, beans and spinach considerable quality losses were recorded during storage at 20 °C. These vegetables could not be stored for longer than 3 days because of strong decay. Storing at 4 °C retarded the decay. All vegetables investigated were well storable at 4 °C for up to 7 days without greater loss in sensory quality. After 14 days of storage at 4 °C substantial quality losses were recorded in peas and beans while spinach could not be consumed any more after a period of 7 days. Carrots and Brussels sprouts were well storable at 4 °C and 20 °C for a long time without greater losses even at room temperature. Of Brussels sprouts, however, yellow and faded leaves had to be removed.

Deep freezing had only little influence on peas and spinach. Frozen beans were very similar to fresh ones in appearance, odour and taste, but there were great changes in texture which turned rubbery. Comparing fresh and frozen non-stored carrots and Brussels sprouts, many differences appeared. There were many changes in taste and texture attributes. To lose the rubbery texture, much longer cooking times should be appled than those used in this study.

Consumers who are used to cooking vegetables to the effect that the produce is very tender would probably not notice the change in texture of frozen carrots, Brussels sprouts and beans. If the vegetables are part of a menu and served in combination with spices and sauces the changes in taste would not be felt as strong.

Key words: Preservation / sensory quality / fresh and frozen vegetables / storage conditions

Sie finden den Artikel in deutscher Sprache in Ernährungs-Umschau 10/06 ab Seite 390.