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Evaluation of hemp protein flours stability
NĚMCOVÁ, Hana
The aim of this diploma thesis is to explore the possibility of storage of hemp protein concentrates extracted by mechanical sifting of milled hemp (Cannabis sativa) seed cake. On the ground of previously acquired scientific knowledge two size fractions of hemp flour were prepared - protein flour containing particles lower than 180 m and fibre flour containing particles larger than 180 m. The two types of flours were subsequently stored for the period of eight months in different conditions. On the stored samples and on the samples before the attempted experience were evaluated following parameters: dry matter, fat content, titratable acidity, antioxidant activity and polyphenol content. The diploma thesis found out the evaluated parameters are statistically significantly affected by the flour's fraction. The type of storage has statistically significant effect on all the parameters, except of the antioxidant activity. The analysis showed that the storage is less suitable for fraction containing less than 180 m because the fraction containing particles less than 180 m is more likely to go rancid given to the larger fat content, shows lower antioxidant activity, contains less polyphenols and tends to become moister. Better outcomes were showed by samples stored in vacuum, of which samples stored at a temperature of 5 °C showed even better results. These samples revealed lower fat dissociation, lower acidity and higher antioxidant activity. However, 9 % moisture that could lead to higher microbial strain was observed.
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Preparation of hemp protein concentrates by mechanical method
NĚMCOVÁ, Hana
A large amount of residual material, which is rich in high-quality protein containing all essential amino acids, remains after pressing hemp seed oil (Cannabis sativa L.). This "waste" can be ground into flour. This thesis examines whether dry sieving of hemp flour could increase the protein concentration in some size fraction to such an extent that it could be used as a protein concentrate. The experiment was carried out on five varieties of hemp from which was the cold-pressed oil acquired. The ground flour was subsequently divided into three size fractions. The coarsest fraction contained particles larger than 250 m, the middle fraction consisted of particles smaller than 250 m but larger than 180 m and the finest fraction composed of particles smaller than 180 m. Proteins were analyzed by various laboratory techniques. Most proteins were found to be in the finest fraction. Their concentration increased here from about 24-27 % to 35-40 %.
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Present possibilities of protein concentrates production from plant sources
KRISTINOVÁ, Helena
The aim of the bachelor thesis was gather information about present possibilities of proteins concentrates production from plant sources. I focused on dried pea (Pisum sativum L.), soybean (Glycine soja) and potato tuber (Solanum tuberosum L.). The protein concentrates from leguminous plants are produced by three basic processes, i.e. acid leasing (at ~pH 4.5), extracting with aqueous alcohol (60 - 90%), and denaturing the protein with moist heat before extraction with water. Pea protein is prepared from pulverized beans or shelled peas by dry or wet treatment. The acquired protein is used in food and feed industry. Soy protein concentrates are prepared from dehulled and defatted soybeans by removing most of the water-soluble, nonprotein constituents. Soy proteins are mostly used in the bakery, in the meat processing industry, in the production of dairy products and healthy food products. Proteins are used in many food products as emulsifiers. The most potatoes are grown for direct consumption, for processing into the food products and for processing of starch is due to the allocated and restrictive quotas, a smaller proportion of cultivated potatoes. In the production of the starch arise a side product PFJ (potato fruit juice). In order to isolate proteins from potato fruit juice appears to be most efficient heat coagulation of steam injection, followed by separation and precipitation of proteins and their preservation by drying. This provides a final product which is offered as a protein feed for domestic and farm animals. Emulsifying properties of undenatured potato proteins have been studied quite intensively, only industrial production of denatured proteins is limited for the one producer in the EU.
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