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Opuntia ficus-indica (L.) Mill. is the Cactaceae plant with the greatest economic relevance in the world. It can be used for medicinal purposes, animal nutrition, production of biofuels and phytoremediation of soils. Due to its high content of bioactive compounds, the prickly pear has antioxidant, antimicrobial and anticancer properties. The aim of this study was to determine the polyphenolic, fatty acid and amino acid profile and characterize the antioxidant capacity of seeds of seven Spanish prickly pear cultivars. A total of 21 metabolites, mainly phenolic acids and flavonols, were identified using ultraperformance liquid chromatography photodiode detector quadrupole/time-of-flight mass spectrometry (UPLC-PDA-Q/TOF-MS). Significant differences were found in the phenolic concentrations of the investigated varieties. The highest amount of phenolic compounds (266.67 mg/kg dry matter) were found in the “Nopal espinoso” variety, while the “Fresa” variety was characterized by the lowest content (34.07 mg/kg DM) of these compounds. In vitro antioxidant capacity was positively correlated with the amount of polyphenols. The amino acid composition of protein contained in prickly pear seeds was influenced by the variety. Glutamic acid was the predominant amino acid followed by arginine, aspartic acid and leucine, independent of prickly pear variety. Overall, 13 different fatty acids were identified and assessed in prickly pear seeds. The dominant fatty acid was linoleic acid, with content varying between 57.72% “Nopal ovalado” and 63.11% “Nopal espinoso”.

PĘksa A., Miedzianka J. (2014): Amino acid composition of enzymatically hydrolysed potato protein preparations. Czech J. Food Sci., 32: 265-272.We determine the effects of the technology of obtaining potato protein preparation and of different variants of enzymatic hydrolysis on the chemical and amino acid compositions of the hydrolysates obtained. Potato protein concentrates obtained through their thermal coagulation in potato juice with calcium chloride, calcium lactate or without salt addition were subjected to enzymatic hydrolysis using two commercial hydrolytic enzymes: endopeptidase (Alcalase) and exopeptidase (Flavourzyme). Chemical (contents of ash, total and coagulable protein) and amino acid compositions of the hydrolysates obtained were determined. On the ground of the findings it was stated that the type of potato protein preparation used and conditions of enzymatic modification influenced on the properties of the hydrolysates obtained. Preparations obtained during the study were characterised by similar chemical and amino acid compositions, whereas the preparation obtained through thermal coagulation with the use of calcium lactate contained insignificantly more protein and essential amino acids. The least liable to enzymatic hydrolysis was the preparation obtained by using calcium chloride, particularly when only endopeptidase was used. The application of endopeptidase enzyme enabled to obtain 60% of proteolysis efficiency and the addition of the second enzyme (exopeptidase) to the protein solution insignificantly increased the proteolysis efficiency (to ca 70%), mainly when the preparation coagulated with the use of calcium chloride was hydrolysed. Proteolysis of the protein preparations obtained with the use of two enzymes was more favourable, particularly due to the quantity of free amino acids in and amino acids composition of the hydrolysates.

The purpose of the present study was to determine the effects of acetylation with different doses of acetic anhydride on the chemical composition and chosen functional properties of commercial pumpkin protein concentrate (PPC). The total protein content decreased as compared to unmodified samples. Electrophoretic analysis revealed that in the acetylated pumpkin protein, the content of the heaviest protein (35 kDa) decreased in line with increasing concentrations of modifying reagent. Acetylation of PPC caused a significant increase in water-binding and oil-absorption capacity and for emulsifying properties even at the dose of 0.4 mL/g. Additionally, an increase in foaming capacity was demonstrated for preparations obtained with 2.0 mL/g of acetic anhydride, whereas acetylation with 0.4 and 1.0 mL/g caused a decrease in protein solubility as compared to native PPC.

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