Rafał Nadulski

Application of Freezing and Thawing to Carrot (Daucus carota L.) Juice Extraction

This paper presents a study of the effects of freezing and thawing carrot pulp and pomace on the efficiency of the pressing process and the quality of juice. In this study, various combinations of pretreatment strategies were used based on freezing and thawing the carrot pulp and pomace before pressing. The pressing process for pulp and pomace was carried out using a laboratory press with a perforated base. The juice obtained as a result of freezing and thawing the carrot pulp and pomace was characterized by a higher sugar content (°Brix) and a slightly lower dynamic viscosity. Furthermore, the study showed the impact of pretreatment on the chemical composition of the juice produced. On the basis of energy use and quality indicators of the resultant carrot juice (viscosity, pH, selected minerals, sugars, total carotenoid content, and vitamin C), a recommended solution is to press the pulp directly after grinding the carrots and then to press the pomace again after freezing and thawing. The proposed method for juice production using freezing and thawing allows a reduction in pomace quantity and the use of its valuable nutrients.

Enzymatic activity of fungi isolated from crops

Aim To detect and assess the activity of extracellular hydrolytic enzymes and to find differences in enzymograms between fungi isolated from wheat and rye samples and grown on Czapek-Dox Broth and Sabouraud Dextrose Broth enriched with cereal (wheat or rye). Isolated strains were also classified in the scale of biosafety levels (BSL). Material and methods The study used 23 strains of fungi cultured from samples of wheat and rye (grain, grain dust obtained during threshing and soil) collected in the Lublin region (eastern Poland). API ZYM test (bioMérieux) was carried out according to the manufacturer’s instructions. Classification of BSL (Biosafety levels) was based on the current literature. Results High enzymatic activity was found in strains cultured in media containing 1% of wheat grain (Bipolaris holmi, Penicillium decumbens) and with an addition of 1% of rye grain (Cladosporium herbarum, Aspergillus versicolor, Alternaria alternata). The total number of enzymes varied depending on the type of media, and in most cases it was higher in the culture where an addition of cereal grains was used. Conclusions Isolated strains of fungi reveal differences in the profiles of the enzyme assay. It can be assumed that the substrate enriched in grains stimulate the higher activity of mold enzymes.

Characterisation of Selected Apple Cultivars in the Aspect of Juice Production in the Condition of a Farm

Pressing is the most common method of fruit juice acquisition. Not all apple cultivars are suitable for juice pressing. The use of suitable fruit cultivars for juice pressing may reduce the cost of pressing and at the same time guarantee high quality of the juice produced. The scope of the study comprised the determination of pressing efficiency and of the quality parameters of apple juice obtained, such as acidity and the content of extract. The results of the study indicate that the efficiency of pressing and the quality of the juice obtained are significantly affected by the varietal traits of the apples. The choice of suitable cultivars allows to achieve a high pressing efficiency and to obtain juice characterised by a high content of extract and high acidity. INTRODUCTION Pressing is the most common method of apple juice acquisition (Markowski, Baron, Le Quéré, Płocharski, 2015). At present, juice pressing under industrial conditions is performed most frequently with the use of presses for periodic operation (mainly baskettype) and for continuous operation (screw-type presses, roller presses or belt presses) (Bump, 1989). Fruit processing methods employed on the industrial scale may significantly alter the nutritional properties of the fruits (De Paepe, Valkenborg, Coudijzer, Noten, Servaes, De Loose, Voorspoels, Diels, Van Droogenbroeck, 2014). Therefore, it is necessary to develop such methods of fruit processing that will minimise the negative effects of the processing on the health-promoting properties of the fruits (Rothwell, Medina-Remón, Pérez-Jiménez, Neveu, Knaze, Slimani, Scalbert, 2015). In certain countries orchard farms are equipped with complete lines for the pressing and delicate preservation of fruit juices. Recently one can observe a development of juice pressing services with the use of mobile presses, which means that juices are produced on site at the fruit producer’s farm (http://mobilejuicefactory.com/mobile-juicing/). As can be seen from the literature data, not all apple cultivars are suitable for juice pressing. The efficiency of the pressing process and the quality of the juice obtained depend on numerous factors, among which the technological properties of raw material play an important role (Renard, Le-Quéré, Baudin, Symoneaux, Le Bourvellec, Baron 2011). In Poland, more than 60 apple cultivars are entered in the National List of Varieties. However, there is a lack of complete knowledge on their applicability for juice pressing. The use of suitable fruit cultivars for juice pressing may reduce the cost of pressing and at the same time guarantee high quality of the juice produced (Eiselea, Drakeb, 2005; Sedov, Levgerova, Salina, Serova, 2010). This justifies research on various apple cultivars in the aspect of estimation of their applicability for juice pressing, especially in farm conditions (orchards), i.e. without the use of specialised preliminary processing of the fruits prior to pressing.

Assessment of Selected Technical Parameters of Soya Seeds Oil Pressing Process

Abstract The objective of the paper was to determine the impact of the value of the oil pressing pressure with the cold pressing method in a screw press on the pressing course and performance. Varied values of pressure were obtained through the use of three replaceable attachments of the pressing unit with a varied diameter of the outlet conduit (ф1=2 mm, ф2=4 mm and ф3=6 mm). The soya oil pressing process performance was determined in relation to the applied attachment and the soya cultivar. Seeds of 7 Polish non-genetically modified soya cultivars constituted research material. It was proved that both variable pressure values and the used soya cultivars have impact on the pressing performance. Based on the analysis of the obtained research results it was proved that varied technical parameters and soya cultivars influence both the process performance and the remaining parameters and pressing conditions.

The assessment of microbiological purity of selected components of animal feeds and mixtures which underwent thermal processing

Microorganisms which contaminate animal feeds pose a threat not only to animals but also indirectly to humans through their consumption of products of animal origin. The aim of the present study was to assess microbiological cleanness of selected resources and ready-made feed mixtures before and after thermal processing. The results indicated that the most bacteriologically contaminated resources were oats (Avena sativa), wheat middlings, wheat (Triticum vulgare), and poultry feed mixture KDKA F35%. The least contaminated were maize (Zea) and Prowit – feed mixture for livestock. The examined feed resources were contaminated with moulds, among which dominated: Aspergillus and Penicillium. The findings of bacteriological and mycological contamination assure instead of allow stating that thermal processing limits microbiological contamination of animal feeds. In order to protect the health of animals as well as consumers it seems advisable to seek new methods of thermal processing in the production of animal feeds to provide their high quality and safety.

The impact of size and shape of particles of undergrowth and herbs mixtures on aerodynamic properties

The impact of the size and shape of a selected group of herbs (dried juniper berries – Juniperus communis, dry blueberries – Vaccinium myrtillus, petals of cornflower – Centaurea cyanus) on the value of the volatility coefficient, the coefficient of sphericity and the critical speed was analysed in the presented research. A laboratory anemometer to measure the speed of air was used. The determination of the volatility coefficient of particular size fractions was conducted on the basis of critical speed values, calculated as an average established after five measurements. The established aerodynamic properties of particular mixtures allow the determination and the assessment of differences among fractions of valuable resources and different impurities. The presented data might constitute a basis to determine the scope of differences among them and establish interrelations which allow the application of proper parameters for the pneumatic separation process in practice.