Anna Korus

The amino acid composition of kale (Brassica oleracea L. var. acephala), fresh and after culinary and technological processing

The aim of the investigation was to evaluate the level of amino acids and the quality of protein in fresh and cooked leaves of kale and in two types of frozen product prepared for consumption after 12-months storage at -20°C. Kale blanched before freezing (the traditional method) was cooked after refrigerated storage, while that cooked before freezing (the modified method) was defrosted and heated in a microwave oven. Both fresh and processed leaves of kale were a good source of amino acids. In all the samples, glutamic acid, proline and aspartic acid were the dominant, while lysine and leucine were the limiting amino acids. Cooked leaves contained 78% of the total amino acid content found in fresh leaves, while the traditional and modified frozen products contained 76% and 78%, respectively. The proportion of essential amino acids in total amino acids was 44% and 43%, respectively for fresh and cooked leaves and 46% for the frozen products. The lowest EAA index was found for the traditional frozen product (99); it was higher for the remaining samples, which were broadly similar to each other (105-106).

Effect of freezing and canning on the content of selected vitamins and pigments in seeds of two grass pea (Lathyrus sativus L.) cultivars at the not fully mature stage

Seeds of the grass pea (Lathyrus sativus L.) cultivars Derek and Krab, with a dry matter content of about 33%, were used for freezing and for canning. The content of vitamins C, B1, and B2 and of carotenoids, beta-carotene, and chlorophylls was determined in raw and blanched material, in frozen products after 6-month storage before and after cooking to consumption consistency, and in canned products after 6-month storage. In comparison with the cultivar Krab, raw seeds of Derek contained 45% more vitamin C, 14% more total chlorophylls, 13% less thiamine (vitamin B1), and 7% less riboflavin (vitamin B2). The level of carotenoids was similar. Blanching of seeds led to a statistically significant decrease only in the content of vitamin C. Freezing and frozen storage significantly lowered the level of vitamin C and chlorophylls. The cooking of frozen seeds and the production of canned products and their storage resulted in a statistically verified reduction in the content of components analysed in all the samples. Greater losses were found in products prepared from seeds of the cv. Krab. After cooking, frozen seeds contained more of all the analysed components than the canned products.

Level of Vitamin C, Polyphenols, and Antioxidant and Enzymatic Activity in Three Varieties of Kale (Brassica Oleracea L. Var. Acephala) at Different Stages of Maturity

The aim of this present study was to determine the level of vitamin C, L-ascorbic acid, polyphenols, antioxidant activity, peroxidase, polyphenol oxidase, and catalase in the leaves of three varieties of kale at different stages of maturity. Average values per 100 g of fresh matter were 102 mg of vitamin C (of which L-ascorbic acid constituted 97%) and 359 mg polyphenols; antioxidant activity was measured at 48.9% RSA (17.6 μM Trolox/g kale). Redbor1 c.v. variety contained the highest levels of the analyzed constituents. Compared with the first stage of maturity, plants at the second stage showed increases of 6% in vitamin C; 28% in polyphenols; and 12% in antioxidant activity, whereas plants at the third stage showed 5, 48, and 22% increased values, respectively. Average POD activity was 7.58 ΔA/min/g, PPO 1.64 ΔA/min/g, and CAT 7.93 mg H2O2/min/g. PPO activity increased with the age of the plant. No consistent correlation was found between the stage of growth and the other enzymes.

Effect of technological processing and preservation method on amino acid content and protein quality in kale (Brassica oleracea L. var. acephala) leaves

BACKGROUND The aim of the investigation was to evaluate the level of amino acids and quality of protein in raw and processed kale leaves. RESULTS In all samples the dominant amino acids in g kg⁻¹ raw matter were glutamic acid, aspartic acid and proline. In raw kale leaves the limiting amino acids were lysine, isoleucine and cystine with methionine, and in the remaining products also valine and leucine. Blanched kale leaves contained 88% of the amino acid content in raw leaves, 76% in cooked leaves, and 69-77% and 71-72% of initial levels in frozen and canned products, respectively. In raw, blanched and cooked leaves essential amino acids comprised 44%, 44% and 47%, respectively, of total amino acids; in frozen and canned leaves the proportions were 46% and 44%, respectively. The essential amino acid index was 97 for canned products, 100-109 for frozen leaves, and 117 for raw kale leaves. CONCLUSION Raw and processed (blanched or cooked) kale leaves are a good source of amino acids.

Effect of maturity stage on the content of ash components in raw and preserved grass pea (Lathyrus sativus L.) seeds.

The grains of grass pea cultivar krab of dry matter content at the level of 26–40 g/100 g were used in the production of preserves by freezing and canning in air tight containers. The content of ash and its alkalinity and of potassium, magnesium, calcium, iron, total phosphorus, and phytic phosphorus was determined in raw and blanched material, in frozen products stored for six months and then cooked to consumption consistency, and in sterilized canned products after the same storage period. With the increasing degree of maturity the content of all the above constituents calculated per 100 g fresh matter, increased. Blanching considerably reduced the level of ash and its alkalinity, of potassium, and of phytic phosphorus. The cooking of frozen seeds and the sterilization in salty brine caused a reduction of the components analysed except for the content of ash, its alkalinity, and of calcium. In comparison with canned sterilized preserves in cooked frozen grains a higher content of all the mineral components was determined.