Zofia Lisiewska

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.

Content of amino acids in fresh and frozen and cooked broad bean seeds (Vicia faba var major) depending on cultivar and degree of maturity

In broad been seeds (cultivars Comprimo RS and Threefoldwhite) harvested at four stages of maturity, which corresponded to dry matter content at the levels of I—25%, II—30%, III—35% and IV—40%, the content of amino acids was determined (g 16 g N−1). The determinations concerned raw broad bean and frozen products cooked for consumption. The content of total and essential amino acids was similar in the two cultivars. With increasing maturity the content of total amino acids and essential amino acids varied, showing a tendency to increase between maturity stages I and IV in all the amino acids, except aspartic acid and alanine in Threefoldwhite. In both cultivars the content of cystine and glutamic acid showed the most rapid rise. Compared with raw broad beans, intact seeds cooked for consumption contained more total amino acids. In products of Comprimo RS the total content of amino acids and essential amino acids was similar in intact seeds and in the dehulled seeds. In products from Threefoldwhite the content of total amino acids and essential amino acids was higher in intact seeds than in dehulled seeds except in the most mature sample where these values were similar. The limiting amino acids were methionine with cystine in both raw broad bean and cooked seeds. © 1999 Society of Chemical Industry

Effect of maturity stages on the content of ash components in raw, frozen and canned broad beans

The aim of the present work was to determine the level of ash, potassium, phosphorus, calcium, magnesium, iron, zinc, manganese, and copper in fresh and preserved broad bean seeds at the stage of milk-wax maturity. The experiments included two broad bean cultivars, four stages of seed maturity being differentiated in each. With the higher maturity stages, the contents of ash, potassium, phosphorus, calcium, and magnesium gradually increased in fresh matter of the two cultivars. The contents of zinc and copper showed a slight decreasing tendency, while the levels of iron and manganese varied. Frozen and canned broad bean seeds of milk-wax maturity, prepared for consumption, were a valuable source of mineral compounds. The more mature the seeds, the greater were the contents of potassium, phosphorus, calcium, magnesium, and manganese, and smaller less so for copper, while the levels of iron and zinc varied. Boiled frozen seeds contained more potassium, phosphorus, magnesium, zinc, manganese, and copper than canned products, no differences being found in the contents of calcium and iron. The dehulled seeds contained more phosphorus but less calcium than the intact ones.

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.

Effect of cultivar and seed maturity on amino acid content in fresh and canned broad bean (Vicia faba v. major)

The content of dry matter, total nitrogen, and amino acids (except for tryptophan) in fresh and canned broad bean (Vica faba v. major) seeds was determined, in the canned product whole seeds or cotyledons without hull being analysed. Two Dutch bred cultivars, Comprimo RS with large seeds and medium sized Threefoldwhite, were investigated at four stages of maturity defined by the content of dry matter at levels of about 25% (stage 1), 30% (II), 35% (III), and 40% (IV). Amino acid content in 100 g fresh weight was similar in the two cultivars, rapidly increasing with maturation. The value of protein expressed by the EAA index was almost the same for the investigated cvs, usually being slightly higher in the case of more mature seeds. Whole seeds from canned product contained slightly less amino acids than the raw material while the EAA index showed similar or slightly lower values for whole seeds than for the raw vegetable. The content of all the amino acids (except for tyrosine) was greater and the EAA indices were higher in the cotyledons of canned broad bean than in whole seeds. Methionine with cystine were the limiting amino acids in fresh and canned seeds.

The effect of processing on the amino acid content in green cauliflower.

The aim of the work was to evaluate the level of amino acids and quality of protein in fresh green cauliflower and in three kinds of products as eaten: fresh cauliflower after cooking; and two types of frozen product: frozen cauliflower obtained using the traditional method (blanching-freezing-frozen storage-cooking); and by the modified method (cooking-frozen storage-defrosting-heating in a microwave oven). Frozen products were stored for 12 months at –20 °C. Fresh inflorescences contained 24.32 g amino acids in 1 kg of edible parts. Expressed as g per 16 g N the content was 86.59 g, with essential amino acids constituting 44%. Culinary processing and the freezing process did not result in a drastic decrease in amino acid content apart from tyrosine. For all the samples the limiting amino acids of the first order was cystine with methionine and of the second order leucine.

Effect of aronia berry honey syrup used for sweetening jams on their quality.

The effects of sweetening agents on the quality of low sweetened jams were compared with respect to blackcurrant, raspberry, sour cherry, strawberry, and bilberry jams. The sweetening agents were sucrose, aronia berry honey syrup, and sucrose + honey syrup at a ratio of 1:1. The level of physicochemical indices, especially the content of vitamin C and anthocyanins determined directly after production and after 3- and 6-month storage, was used as the quality criterion for the evaluation of jams. Moreover, after 6-month storage the products were subjected to sensorial analysis. According to the accepted method of the investigation the produced jams were characterized by a 32-33% content of extract. During the production and 6-month storage the content of acids slightly and that of pectin considerably (from 26 to 46%) decreased, although the consistency of the jams was not affected thereby. In the case of vitamin C, its pronounced losses concerned raspberry (62-67% of the initial value), strawberry (57-61%), and sour cherry (57-58%), being distinctly smaller in blackcurrant (13-16%) and bilberry (15-35%) jams. With respect to anthocyanins a similar regularity was observed, the losses reaching 49-63% in strawberry jam, 40-56% in raspberry, 33-39% in sour cherry, 30-36% in blackcurrant, and 28-36% in bilberries. In almost all the products the losses of vitamin C and anthocyanins were higher when sweetening agent was aronia berry honey syrup. The organoleptic evaluation showed that the addition of aronia berry honey syrup to raspberry and strawberry jams slightly spoiled their colour but improved the aroma and taste. In the final score the significant differentiation in favour of the addition of aronia berry honey syrup concerned only blackcurrant, sour cherry, and bilberry jams.

Zinc retention in vegetables according to the method of preparation for consumption

The aim of the present work was to evaluate the retention, the nutrient density and the recommended daily allowance of zinc in 14 common vegetable species prepared for consumption. The investigation included fresh vegetables, vegetables after traditional cooking in brine and two types of frozen products: one obtained using the traditional method (blanching–freezing–storage–cooking in brine) and the other obtained using the modified method, providing a ready-to-eat product (cooking in brine–freezing–storage–defrosting and heating in a microwave oven). A significant zinc decrease was found in most studied vegetables prepared for consumption. Application of the modified method contributed to a reduction in zinc losses in prepared-for-consumption frozen vegetables.