Vitamin C losses in some frozen vegetables due to various cooking methods

Abstract

Frozen spinach, peas, green beans and okra were commercially cooked in three different stewpans (double based stainless steel, teflon, pyrex) with and without thawing. The vitamin C levels were effected both by cooking methods and stewpans. Frozen peas were found to be the least (3.5% loss), and frozen green beans were found to be the most (19.6% loss) effected vegetables by thawing. In all of the stewpans, double based stainless steel pan retained more vitamin C than the others. While boiling spinach, peas, green beans, and okra without thawing resulted 46.5, 25.2, 18.2, and 21.6% vitamin C loss in double based stainless steel pan, boiling them in pyrex pan resulted 58.5, 36.0, 42.1, and 28.2% vitamin C loss, respectively. Besides, the losses in cooking processes were accelerated in thawed vegetables with the same tendency; that is more destruction occurred in samples boiled in pyrex pan (60.3% loss in spinach, 40.8% loss in peas, 48.4% loss in green beans, and 41.6% loss in okra). According to the results, it was found that thawing before cooking is useless and causes more vitamin C loss. Therefore, frozen vegetables must not be thawed before cooking. In order to prevent vitamin C from destruction, using double based stainless steel pan, minimum amount of water and cooking of frozen vegetables are recommended.

Vitamin C: Overview and Update

“…85,86 However, the stability of vitamin C in foods is precarious and readily influenced by oxygen, heat, pH, and metallic ions, resulting in the oxidation of vitamin C. 87 Vitamin C is well preserved in frozen foods; hence, orange juice reconstituted from frozen concentrate is a better source of vitamin C as compared with ready-to-drink orange juice (86 mg/serving vs 39-46 mg/serving). 88 Cooking reduces the vitamin C content of vegetables by 40% to 60%, 89 and prolonged warming of foods (150 F for 4 hours) reduces vitamin C content >75%. 90 Vitamin C losses during vegetable storage are as high as 70%; hence, if vegetables are not purchased…”

Vitamin losses: Retention during heat treatment and continual changes expressed by mathematical models

“…Cooking losses of L-ascorbic acid depend on the degree of heating, leaching into the cooking medium, surface area exposed to water and oxygen, pH, presence of transition metals, and any other factors that facilitate oxidation (Eitenmiller and Laden, 1999). Nursal and Yu¨cecan (2000) observed changes in frozen spinach, peas, green beans, and okra commercially cooked in different stewpans with and without thawing. Frozen peas were the vegetables found to be the least (3.5% loss) affected, and frozen green beans the most (19.6% loss) affected by thawing (at room temperature 22.372 1C, 3 or 4 h, respectively).…”

Petechial Rash in a Child with Autism and Trisomy 21

“…Preservation and cooking methods may decrease vitamin C content. 16 At low doses, vitamin C is highly absorbed; higher doses are less avidly absorbed and undergo urinary excretion. Daily intake of as little as 10 mg of vitamin C (present in 20 g of orange or 50 g of potato) has been shown to reverse symptoms of scurvy.…”