Effects of selected lactobacilli on the functional properties and stability of gluten-free sourdough bread.

The aim of this investigation was to determine the influence of seven different Lactobacillus spp. (Lb.) strains compared with a commercial starter culture (CS) on the functional properties of gluten-free (GF) sourdough-breads. The sourdough stability of selected strains was also evaluated upon back-slopping. Results showed that the bread properties were greatly affected by the Lb. strains. Millet breads achieved lower specific volumes (1.80-2.19 cm3/g), higher crumb firmness (19.01-42.19 N) and lower relative elasticities (21.5-43.4%) than buckwheat breads. Compared with the CS, Lactobacillus pentosus and Lb. hammesii positively influenced the crumb firmness of buckwheat and millet breads, respectively, while Lb. paralimentarius enhanced this property in both breads. Only one of the two Lactobacillus sanfranciscencis strains was able to improve all functional properties in both GF breads. Back-slopping of the sourdoughs revealed stable properties in case of buckwheat, while maturity of the millet sourdough could not be reached. These observations were supported by the microbial count, metabolite production and carbohydrate consumption. Mature sourdough significantly improved the crumb firmness and porosity of the GF breads. These results highlighted the importance of selecting the appropriate lactic acid bacteria strains, to maximize the quality of GF bread.

Human utilization of triticale: technological and nutritional aspects.

In spite of the fact that triticale is not subject of the EU intervention, its acreage shows a continuously growing trend. Albeit, both parental species (sp. Triticum, sp. Secale) are used for human food, the utilization of triticale as human food is still uncertain. The main focus of this paper was to study and compare technological and nutritional values of triticale and its parental species. Triticale (cultivars and experimental lines) along with one wheat and one rye varieties were used in the tests. Most of the grain and flour technological properties (Kernel diameter, Test Weight, flour yield, gluten content, Zeleny volume) of the triticale entries positioned in between the parental wheat and rye attributes. However, thousand kernel weight (TKW) of triticale cultivar GK Szemes and grain hardness of cv. GK Idus surpassed all other entries. The study revealed that--having considerable variation--triticale grains are very rich in beneficial elements such us Ca, Mg, P, Cu and Zn. Dietary fiber (DF) content of triticales were between the rye and wheat controls (10-15%). Total arabinoxylan content (TOTAX) of triticales were much closer to rye (6%), and in some genotypes considerably expanded it (6,5-7%). Health conscious consumers trend to use increasingly novel, valuable grain sources and products in their daily based diets. The inappropriate nature of triticale per se flours for baking industry seems to hinder the human utilization. Blends exploiting favorable attributes of triticale may be a suitable way to use this valuable crop in milling products and in larger food industrial scale.

Relationship between concentration of citrate and ketone bodies in cow's milk.

The authors' hypothesis is that the members of the tricarboxylic acid cycle (TCA cycle) such as citrate decrease in association with increased ketone body formation. To prove this hypothesis the connection between ketone bodies and citrate formation of milk was studied. A fluorimetric method was used to determine citrate and a headspace sampling gas chromatographic (GC) method was developed for determination of ketone bodies. Under real conditions of milk sampling, transport and storage, preserved milk samples of 119 clinically healthy dairy cows obtained in the 48 hours after milking were investigated. A low level of acetoacetate (ACAC) was found in all samples. This fact can be explained by the spontaneous decarboxylation of acetoacetate during sample storage (previously decarboxylised acetoacetate = pdACAC) and, consequently, the majority of the amount of acetoacetate in the samples (AC + pdACAC) appeared in the measured acetone concentrations. Based on the measured acetone concentration of milk samples two groups were formed retrospectively: HA (high-acetone) group (n = 41) with an AC + pdACAC concentration of > 0.4 mmol/l and a LA (low-acetone) group (n = 78) with an AC + pdACAC level of < or = 0.4 mmol/l. In the milk of cows of Group HA a positive correlation (r = +0.623) and linear connection between acetone (AC + pdACAC) and beta-hydroxybutyrate (BOHB) levels was found [BOHB = 2.491 + 0.586 x (pdAC + ACAC)]. Furthermore, in this group a negative correlation between citrate and BOHB and AC + pdACAC was also established (r = -0.579). Focusing on the results of this group the authors found a significant drop of AC + pdACAC and citrate during the metabolically critical first 1-4 weeks of lactation. For this reason they suggest that simple, easy, automated methods (i.e. flow injection analysis, Fourier transformation infrared analysis) should be introduced for the simultaneous determination of acetone and citrate concentration in milk to make the evaluation of the energy status of high-producing dairy cows easier and more certain.

Determination of total cholesterol content in food by flow injection analysis with immobilized cholesterol oxidase enzyme reactor.

A new analytical method has been developed--including a new sample preparation procedure--for the automatic determination of total (free and bound) cholesterol in food by flow injection analysis (FIA) with immobilized (cholesterol oxidase) enzyme reactor (IMMER). A suitable sample preparation procedure has been applied to eliminate the problems derived from sensitivity of FIA equipment to common organic solvents used for dissolving of cholesterol: after direct saponification the non-saponificable fraction was dissolved in water phase detergent (sodium cholate) solution. The analytical method is based on the oxidation by cholesterol oxidase followed by the photometric determination of hydrogen peroxide (at 500 nm) using the indicator reaction with peroxidase. The new FIA method was tested for commercial food samples such as whole egg powder and dried pasta. The results were compared with data obtained by GC-determination. It was found that this new procedure is suitable for rapid automated measurement of total cholesterol content in foodstuff and consequently, the FIA technique with immobilized enzyme reactor could be an alternative to the widely used gas-chromatographic (GC) method.

Isolation, functional properties and potential use of protein preparations from lupin.

Protein isolates were prepared by extraction with diluted NaOH (resulting the highest yield) and precipitation with HCl from lupin seeds grown in Egypt and Hungary. Protein content, amino acid composition, biological value and functional properties of isolates were studied. The proteins were high in lysine but relatively low in sulfur-containing amino acids. Good solubility and moderate emulsifying, foaming and gel-forming properties of isolates were observed. Enrichment of fruit- and vegetable-based baby foods with these isolates resulted in products with excellent organoleptic properties and moderate biological value. Additional enrichment with small quantities of methionine increased significantly the biological value without any negative changes of organoleptic characteristics.

Isolation and study of the functional properties of pea proteins.

Proteins of pea seeds were isolated after defatting with hexane using alkaline (0.1 M sodium hydroxide) extraction and acid (HCl) precipitation. Concentrates were also prepared by hexane extraction and ethanolic extraction (pH = 5). Gross chemical composition amino acid content and functional properties (solubility profile, emulsifying--and foaming properties, water--and oil absorption) were studied. The results were compared with the same parameters of soy and lupin protein products. Although the majority of functional characteristics of isolates were lower in comparison to soy isolates, pea protein concentrate and isolate could be successfully used in bakery products for enrichment in protein and improvement of biological value. Their utilization as meat protein substitute in some Frankfurter type sausages is also possibly.