Elżbieta Dłużewska

Effect of transglutaminase additive on the quality of gluten-free bread

The aim of the work was to determine the impact of addition of transglutaminase (TGase), soy and whey protein on physicochemical and sensory properties of gluten-free breads. Samples were produced from concentrates consist of 7% of soy or whey protein. TGase was added in amount of 1, and 10 U/g of protein. Following features have been marked for each gluten-free bread sample: specific mass, specific volume, crumb porosity, moisture and crumb hardness. One observed that more valuable changes have been observed for the samples with soy protein; in particular, addition of 1U/g of TGase to gluten-free breads with soy or whey protein improves several physicochemical and sensory features of gluten-free breads. An impact of TGase into quality of gluten-free breads depends on the type of proteins that has been used. Samples with addition of 1U TGase were better assessed by consumers in comparison with other analyzed samples.

The study of palm and rapeseed oil stability during frying

Palm oil is characterized by high oxidation stability, high smoke point, low foam making properties, limited penetration into the product, what makes it ideal for processes requiring thermal treatment such as frying. The aim of the study was to investigate the chemical composition and thermooxidative stability of red palm olein, rapeseed oil and their mixtures during deep-frying of French fries. Analysis of fatty acids composition and basic parameters of fresh oils (acid number, peroxide value, polar compounds content, induction time) were performed. During frying, changes in acid number, polar compounds in oils as well as consumers’ acceptance of the fries fried in these oils were investigated. During the 32-hour of frying, the lowest chemical changes occurred in palm olein, what was confirmed by low acid values (0.99 mg KOH/g) and low polar content (14.4%). At the end of the experiment, the oil mixture had the highest polar fraction value of 25.0%. In the opinion of consumers, fries fried in rapeseed oil were “the best”, while French fries fried on palm oil were considered “artificial”, “chemical” and “disgusting”. The reason for this opinion was the addition of β-carotene to this oil. On the other hand β-carotene from palm olein had a great positive effect on the colour of the fries, but at the same time had a negative effect on the taste.

Oxidative Stability of Selected Edible Oils

The aim of the study was to examine and compare oxidative stability of refined (peanut, corn, rice bran, grapeseed, and rapeseed) oils. The oils were subject a Schaal Oven Test (temperature 63 ± 1 °C) and a Rancimat test (temperature 120 °C) and their stability was compared at the 1st and 12th month of storage. Changes in the peroxide (PV) and anisidine (AnV) values in the thermostat test were the fastest in rapeseed oil and grapeseed oil. The best quality was preserved by peanut and corn oils both in the first and the twelfth month of storage. The induction times for the rice bran, corn, peanut, and rapeseed oils were similar from 4.77 h to 5.02 h in the first month and from 3.22 h to 3.77 h in the twelfth month. The shortest induction times were determined for grapeseed oil: 2.4 h and 1.6 h, respectively. A decrease of oxidative stability of about 30% was found in all the oils after 12 months of storage. The PV of 10, determined in the thermostat and Rancimat tests, were achieved at the latest in corn oil and the fastest in rice bran oil.