Dubravka Jambrec

Determination of Volatile Organic Compounds in Selected Strains of Cyanobacteria

Microalgal biomass can be used in creating various functional food and feed products, but certain species of microalgae and cyanobacteria are known to produce various compounds causing off-flavour. In this work, we investigated selected cyanobacterial strains of Spirulina, Anabaena, and Nostoc genera originating from Serbia, with the aim of determining the chemical profile of volatile organic compounds produced by these organisms. Additionally, the influence of nitrogen level during growth on the production of volatile compounds was investigated for Nostoc and Anabaena strains. In addition, multivariate techniques, namely, principal component analysis (PCA) and hierarchical cluster analysis (HCA), were used for making distinction among different microalgal strains. The results show that the main volatile compounds in these species are medium chain length alkanes, but other odorous compounds such as 2-methylisoborneol (0.51–4.48%), 2-pentylfuran (0.72–8.98%), β-cyclocitral (0.00–1.17%), and β-ionone (1.15–2.72%) were also detected in the samples. Addition of nitrogen to growth medium was shown to negatively affect the production of 2-methylisoborneol, while geosmin was not detected in any of the analyzed samples, which indicates that the manipulation of growth conditions may be useful in reducing levels of some unwanted odor-causing components.

Relationship of Physicochemical Characteristics with Sensory Profile of Cookies Enriched with Medicinal Herbs

In this work, a range of model cookies enriched with different quantities of medicinal herbs, applied in two forms (pulverized mixture and extract), were studied to compare and describe relationships between physicochemical and sensory data. Multivariate statistical methods were applied to estimate relationships in the analyzed data. Analysis of variance showed that the majority of analyzed parameters were highly significant in discriminating among the samples (p < 0.05), which supported the usefulness of their application in characterizing the quality profile of enriched cookies. Principal component analysis on physicochemical data revealed that cookies at the same enrichment level showed more similarities. Principal component analysis on sensory data exhibited a larger separation between the samples with increasing enrichment levels, especially in the case of pulverized herbal mixture. According to partial least squares regression, two significant partial least squares components explained 92.7% and predicted 78.0% variation in the data. The most important parameters in discriminating between the cookies enriched with medicinal herbs were lightness, red tonality, and hardness. The selected physicochemical parameters could be used in future studies to evaluate variously enriched cookies by establishing models and investigating the predictability of sensory quality.

Solid Fat Content, Pre-Crystallization Conditions, and Sensory Quality of Chocolate with Addition of Cocoa Butter Analogues

The objective of this study was to determine how the addition of two cocoa butter equivalents and cocoa butter improver affect the physical and sensory properties of chocolate. The laboratory-made chocolate samples were tempered at three different pre-crystallization temperatures (25, 27, and 29°C), using different concentrations (3, 5, and 7%) of two commercial cocoa butter equivalents as well as commercial cocoa butter improver of the chocolate. The nucleation time of the chocolate mass primarly depended on pre-crystallization temperature while the value of maximum torque of chocolate mass were influenced by both, pre-crystallization temperature and concentration of fats. Sensory evaluation revealed that cocoa butter equivalents were acceptable in chocolate formulation without producing a negative impact on the sensory quality, while usage of improver required adjustment of raw formulations or process parameters. The results of the instrumentally measured hardness revealed that addition of cocoa butter improver significantly (p > 0.05) increased hardness of chocolate samples.

The influence of plant protein on the properties of dough and the quality of wholemeal spelt bread

The paper presents the effect of a soy protein concentrate (protein content 65%) as a substituent (substituting 20% wholegrain spelt flour) and a pea protein isolate (protein concentration 90%) as a substituent (substituting 5% and 10% wholegrain spelt flour) on the rheological characteristics of spelt dough and on the physical and sensory characteristics of spelt bread enriched with proteins. The stability of dough supplemented with a soy protein concentrate has turned out to be higher than the stability of dough supplemented with pea protein isolates. It is probably the result of different protein behaviour in soybeans and peas. The applied ingredients have manifested different effects on the specific bread volume. In comparison to the control bread, the specific volume of bread samples have been reduced significantly with addition of a 20% soy protein concentrate and a 10% pea protein isolate (from 1.83 ml/g to 1.39 and 1.38 respectively). On the other hand, addition of a 5% pea protein isolate has not brought to a significant decline in the specific bread volume. Addition of a 10% pea protein isolate has increased the chewiness while this parameter has not changed significantly in relation to the control bread with addition of 5% pea protein and 20% soy protein. Spelt bread with 5% pea isolated protein is the most acceptable according to the overall sensory acceptance among all the analysed samples.

Soy Bran Separation Process for Application of Product in the Food Industry

Change of lifestyle, also as contemporary dietary habits of people, requires innovations in the food processing technology and implementation of new ingredients. Fat replacers are well known as ingredients which has been used in the production of low energy products. Furthermore, in the combination with sugar substitutes it is possible to obtain serious energy reduction, while the sensorial properties remains unaffected. A certain lightweight fractions of soy bran separation and milling process could be applied as fat replacers in the food industry, especially in cookie production. Soy bran milled fractions with dietary fibers content (cellulose, hemicellulose, lignin, inulin, pentosans etc.) have been selected for this work. Technological process of soy bran separation and milling starts with a cleaning of the external part of the soy grain, further it is necessary to adjust the moisture content for the efficient mechanical grinding process. New age milling and separation equipment (air separator, cascade classifier, dryer, hammer mill, roller mill) was used for the purposes of experiment. Results obtained with the analyze of microbiological and chemical properties of soy products, along with a probe sieving analysis, indicates a strong potential for use as fat substitutes in bakery, cookie and confectionery production.