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sodium, 712.43, 606.34 and 586.53 mg/100g potassium, 407.65,
302.52 and 292.64 mg/100g calcium, 637.18, 558.71 and 551.27
mg/100g magnesium content, for fresh, after blanching and after
freezing process, respectively. This study showed that blanching and
freezing delays the degradation of nutritive value of frozen vegetable
products.

Key words: Vegetables; Moisture; Protein; Fat; Carbohydrate; Fiber;

Ash; Ascorbic acid; Minerals content.

INTRODUCTION

As a pre-freezing process, blanching is used to inactivate en-
zymes that cause detrimental changes in color, flavor and nutritive
value during frozen storage (Brewer et al., 1995); however, this treat-
ment can also cause loss of such characteristics (Murcia et al., 2000).
According to Brewer et al. (1994), the loss of water-soluble minerals
and vitamins during blanching should also be minimized by keeping
blanching time and temperature at an optimum combination. Almost
every vegetable needs to be blanched and rapidly cooled prior to
freezing (Sipos et al., 2009), and this process is usually achieved with
the use of heat (boiling water, steam or microwave) for a short period
of time. Blanching is usually carried out between 75 and 95ºC for 1
to 10 minutes, depending on the size of individual vegetable pieces
(Thane and Reddy 1997). Steam blanching takes longer than the wa-
ter method, but helps retain water-soluble nutrients, such as some vi-
tamins and minerals (Barbosa-Cánovas et al., 2005). After blanching,
the product should be rapidly cooled down to minimize the degrada-
tion of heat-labile nutrients (Barbosa-Cánovas et al., 2005).

According to Selman (1992), freezing process itself does not alter
the nutritive value of the product being frozen. It is during the pre-
parative steps prior to freezing, particularly blanching, and during

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