Potential indicator enzyme s at broccoli blanching tecnology

Abstract

Blanching of vegetables before freezing has some advantages as well as a number of disadvantages. Process optimization involves measuring the rate of enzyme destruction, such that the blanching time is just long enough to destroy the indicator enzyme. Eventually, peroxidases were almost universally the enzymes of choice, as they are usually the most heat-stable enzymes found in vegetables and fruits, so by the time they are inactivated no other enzymes or micro-organisms remain. But there is no evidence that peroxidases are involved in deteriorative reactions in the food.The aim of this work was to improve blanching technology in Hungarian frozen food industry with special emphasis on broccoli treatment. Instead of peroxidases, lipoxygenases were chosen to determine the adequate blanching parameters. Usually, lipoxygenases accompany lipases, so lipase activity is measured, too.On the basis of model blanching experiments, the conclusion is that lipoxygenase could be used as indicator enzyme. Being less heat stable than peroxidase, this enzyme requires shorter heat treatment, hence its inactivation should result in minimum quality deterioration and economic loss.

Study of lipoxygenase and peroxidase as indicator enzymes in green beans: change of enzyme activity, ascorbic acid and chlorophylls during frozen storage

“…Some researchers suggested that targeting peroxidase leads to a more severe heat treatment than is required for many vegetables and that the enzymes responsible for quality loss, which have been identified, have a lower stability than peroxidase (Reid, 1998). Recently, use of LOX as an indicator of proper blanching has been recommended as more significant in determining storage stability in frozen vegetables (Barrett & Theerakulkait, 1995;Nagy-Gasztonyi, Kardos-Neumann, & Biacs, 2000;Sheu & Chen, 1991;Williams, Lim, Chen, Pangborn, & Whitaker, 1986).…”

Study of lipoxygenase and peroxidase as blanching indicator enzymes in peas: change of enzyme activity, ascorbic acid and chlorophylls during frozen storage

“…POD appears to be one of the most heat stable enzymes present in vegetables and it has been generally accepted that if POD is destroyed then it is quite unlikely that other enzymes will have survived (Halpin & Lee, 1987 enough to inactivate POD is generally more than enough to destroy the undesirable enzymes, since POD activity has not been shown to be directly responsible for quality deterioration during frozen storage of vegetables. The use of LOX as indicator of proper blanching has been recommended as more significant in determining storage stability in frozen vegetables (Williams et al, 1986;Sheu & Chen, 1991;Barrett & Theerakulkait, 1995;Nagy-Gasztonyi, Kardos-Neumann, & Biacs, 2000). LOX has been associated with quality deterioration because of its involvement in offflavor and odor production, loss of pigments such as carotenes and chlorophylls, and destruction of essential fatty acids (King & Klein, 1987).…”

Farm to Fork Stability of Phytochemicals and Micronutrients in Brassica oleracea and Allium Vegetables

“…Typical indicator enzymes are peroxidase and lipoxygenase. 120 Additionally, blanching helps remove tissue gases. For most vegetables, blanching is performed for several minutes (typically 1 to 5 min) by immersion in hot water (typically in the range of 88 to 99 °C).…”