Operational Degradation of Engine Oil in Agricultural Technology

Proposed paper is focused on description and observation of operational degradation of engine oil in agricultural technology. Engine oil is one of the most important liquids used in combustion engines. Correct function of any machine is based on the appropriate selection of lubricants; moreover, it is also important to care for the entire lubrication system. Determining the condition of the oil used in operational conditions is very important for potential further oil use. Previously, engine oil had to be changed after expiration of legally valid intervals regardless of its actual performance parameters. However, its usage may be extended if engine oil parameters meet the legal requirements. This can be achieved by removing engine oil samples from machines on a regular basis. By examining the samples taken, it is possible to determine the actual oil state. In such manner, it is possible to prolong interchange periods and save both the financial resources and environment.O

Mechanical properties of sugar beet root during storage

This paper is an investigation via two experimental methods, of the textural properties of sugar beet roots during the storage period. In the work, sugar beet roots mechanical properties were evaluated during the post-harvest period - 1, 8, 22, 43, and 71 days after crop. Both experimental methods, i.e. compression test and puncture test, suggest that the failure strength of the sugar beet root increases with the storage time. The parameters obtained using the puncture test, are more sensitive to the storage duration than those obtained by way of the compression test. We also found that such mechanical properties served as a reliable tool for monitoring the progress of sugar beet roots storage. The described methods could also be used to highlight important information on sugar beet evolution during storage.O

Rheological behaviour of chocolate at different temperatures

The rheological behaviour of the chocolate at different temperatures was studied using a concentric cylinder viscometer with precision small samples adapter, temperature sensor and standard spindle. BIO chocolate (100% organic cocoa) has been used for the whole types of experiments. At the first, the range of temperature has been chosen 36 oC, 38 oC, 40 oC, 42 oC, and 44 oC. The shear deformation rate was established from the 0.1 s-1 up to 68 s-1. Rheological behaviour was non-Newtonian (plastic) with inconsiderable yield stress in all temperatures. The chocolate unambiguously demonstrated plastic behaviour and flow curves were fitted by the power law model (Herschel-Bulkley model), Bingham model, and Casson model with taking into account the coefficient of determination R2. The obtained results of rheological behaviour of chocolate can be best described as Casson fluid. Exactly coefficients of models can be used for modelling of flow velocity, volume flow, friction factor, Reynolds number, two dimensional and three dimensional velocity profiles and much more for flow in the real technical elements e.g. pipes, trough, tubes. Finally, temperature dependence of apparent viscosity of chocolate was also continuously measured in the range from 35 oC up to 62 oC. The apparent viscosity decreased in the temperature range. This decrease was fitted using power law equation. The knowledge of the plastic flow behaviour of chocolate is very important, because it is not quite common flow behaviour of foodstuffs.O

Effect of ripening time on colour and texture properties in cheese

The group of semi-hard cheeses is quite heterogenous and there are distinctions between individual representatives of this group. The aim of this paper was a comparison the colour changes and texture properties of semi-hard pasta filata cheeses during ripening. Spectrophotometer Konica Minolta CM-3500d was used for the colour measurements of cheese samples. Color parameters L* a* b* were determined for the edge part and for the middle part of samples. The texture properties of cheese were measured by TIRATEST 27025. Measurements were made for part following the edge and the middle part of samples as well. During ripening of cheese samples there were observed statistically significant changes in the colour parameters of the edge part of oiled cheese. Total colour difference (ΔE *ab) during storage was the most noticeable in first 10 days of ripening. In compare with changes in a* parameter of the edge part of cheese samples, red tone (a* parameter) in the middle part of cheese samples did not show so large change. The measured strenght of edge part of the cheese samples was in range between from 7.44 N up to 23.49 N. Firmness of middle part varied from 4.46 N to 24.40 N in 60 days of maturating.O

Quality parameters of curd

The aim of this work was measurement of the curd firmness prepared by different volume of rennet solution and comparison of differences of curd firmness between these volumes. Further, it was observed the influence of different volumes of rennet up to thevolume of whey release, curd firmness, dry matter of curd and dry matter of whey. The composition of milk was determined according ISO and Czech state standard. Dry matter content (%) was determined by gravimetry, in drying oven at 102 oC to constant weight (ISO 6731:2010), the protein content (%) by Kjeldahl's method (EN ISO 8968-1:2002), content of fat (%) by Gerber's acidobutyrometric method (ISO 2446:2008), content of lactose by polarimetry, titratable acidity by titration Soxhlet-Henkel method, pH and calcium content in milk (g.L-1) was determined by complexometric titration with flueroxone as an indicator according to Czech state standart No 57 0530. For coagulation was used microbial rennet CHY-MAXRM 200. There were measured: curd firmness, rennet coagulation time, curd quality, volume of released whey, weight of curd, dry matter of curd and dry matter of whey. Different volumes of rennet solution had influence on curd firmness. Curd firmness (volume of rennet solution) had no significant influence on curd quality (five grade scale). Curd firmness had influence on volume of whey release (mL) out of the curd. With the increasing curd firmness s increased the volume of whey released from the curd. The volume of rennet solution had an influence on weight of curd. Curd dry matter raised with higher volume of rennet solution. Volume of added rennet solution had no statistically significant effect on the change of whey dry matter.O

Effect of additives to microbiological quality of yogurts

The objective of this work was to study the effect of addition chia flour, quinoa flour, nopal powder, apple fibre and bamboo fibre BAF 40 in yogurt to microbiological quality. Yogurts were made with 1, 3 and 5% of addition of these additives. The milk used for manufacturing was heated up to 85oC for 5 min and flour, powder and fiber were irradiated for 20 min in three replicates. It was monitored: Lactic acid bacteria (LAB) - 72 hours at 30oC (ISO 13721:1998) and yeasts and moulds - 5 days at 25oC (ISO 21527-1:2009). During storage, the number of LAB was increased to match the initial concentration of yogurt with addition chia flour (concentration 1, 3, 5%) and quinoa flour (1%). The addition of nopal powder, apple or bamboo fiber to yogurt showed a tendency to decrease the number of LAB compared with its initial concentration. All samples were compared with the control yogurt without addition whatever flour, powder or fiber. The amount of yeasts and moulds was increased with the increasing addition of fiber in yogurts. The lowest amount of yeasts and moulds was in yogurt with the bamboo fiber. On the other hand the highest amount was in yogurt with chia flour.O

Effect of different storage times on Japanese quail egg quality characteristics

The aim of this research was to monitor selected quality parameters of Japanese quails (Coturnix coturnix japonica) - the loss of egg weight, changing yolk and white index, Haugh units, egg yolks color. Quail eggs were stored for 0, 1, 2, 4, 6 and 8 weeks at 4 oC. The weight of the quail eggs ranged from 11.67 to 12.27 g. The ratio of the shell range 7.60 to 8.16 % (resp. 0.89 - 0.96 g), ratio of egg white from 59.33 to 62.10 % (resp. 6.31 - 6.66 g) and a ratio yolk of 30.13 - 32.88 % (resp. 3.68 - 3.91 g). The lost of egg weight ranged from 0.47 to 2.93 % during the quail eggs storage, corresponding to a weight loss of 0.26 - 0.58 g of the total weight of the eggs. The average values of the yolk index ranged from 42.67 - 48.53 % and the average values of the quail egg white index ranged from 6.77 to 11.35 %. The average Haugh units were set between 56.93 and 73.72. The color of quail egg yolk was determined using the La Roche scale with the most frequent value 3. During the quail eggs storage, a statistically significant difference was found with most of the quality traits observed.O

Study of rheology and friction factor of natural food hydrocolloid gels

Differences in the rheology and friction factor of natural food hydrocolloid gels were studied in this paper. The practical importance of the knowledge of the rheological parameters is quite evident. The experimental data were carried out using a concentric cylinder rotary viscometer. It was prepared 1% hydrocolloid solutions (hydrogels). Hydrogels of the natural gums extracted from the seeds of the plants and plant tubers have been used - carob gum (from the seeds of Ceratonia siliqua), guar gum (from the seeds of Cyamopsis tetragonoloba) and tara gum (from the seeds of Caesalpinia spinosa). Rheological behaviour has non-Newtonian pseudoplastic character and the flow curves were fitted using the Otswald - de Waele (power law) model and Herschel - Bulkley model. The hydrogels exhibit shear thinning behaviour. The meaning of the rheological parameters on the friction factors during flow of hydrocolloid gels in the tube has been shown. Information on time dependent behaviour of tested liquids has been also obtained. Time dependent curves were fitted by the Gaussian model. Preliminary results obtained for a constant shear rate showed the thixotropic and time-dependent behaviour of the hydrogels. These parameters can be especially used in much software dealing with a numerical simulation of the flow problems.O

Antioxidant activity of yoghurt supplemented with natural additives

The aims of this study were the estimation of difference in physiochemical properties and antioxidant activity of yoghurts supplemented by different natural additives. In addition, the changes in physiochemical properties and antioxidant activity during five weeks storage were performed. The change in antioxidant activities was evaluated using the ABTS radical cations decolorizing assay. The statistical analysis showed that the yoghurt samples with the natural supplement have higher antioxidant activity than the plain yoghurt. In addition, the storage period affect the yoghurt properties by increasing its acidity and antioxidant activities by increasing the storage time. Furthermore, the plain and supplemented yoghurts are still consumable until the fifth week of storage but the favourable time to consume it with its higher antioxidant capacity is the 3rd week of storage

Phthalic acid esters content in yoghurt with chia flour and bamboo fiber during storage time

Phthalic acid esters are plasticizers, they can migrate freely from plastic to their surroundings. They have negative health effects. European legislation sets specific migration limits for phthalic acid esters. In our study, we deal with two esters of phthalic acid, dibutylphtalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP). It was studied the effect of storage of four types of yoghurt on the concentration of phthalic acid esters. Yoghurts contained 1% chia flour, 5% chia flour, 1% bamboo fiber and 5% bamboo fiber. Yoghurts were stored in plastic cups, which contained both examined phthalic acid esters. Esters of phthalic acid were determined after 1 week of storage then after 2 weeks of storage and in the original raw material. Furthermore, the pH of the yoghurt was determined. The pH values ​​were correlated with phthalate concentrations: the correlation coefficient for DBP with a pH of -0.0265 and for DEHP with a pH of 0.3075. Mean concentrations of DEHP decreased over time, while DBP decreased for yoghurt with 1% chia flour, while in other cases they increased. The mean DBP concentrations in yoghurt were higher than the average concentrations of DEHP. Comparing the mean sample values ​​with t-test for dependent samples for yoghurt of the same type, when comparing the DBP or DEHP concentration in week 1 with the DBP or DEHP concentration at week 2, the mean values ​​were consistent. It can be noted that there was no increase in DEHP concentrations from cups to yoghurts, which was probably due to a lower concentration in cups than the DBP concentration. DBP concentrations increased in 3 of the 4 types of yoghurt. The determined pH in yoghurts did not differ significantly. Apparently a greater effect on the migration of phthalic acid esters will have in our case a different yoghurt consistency than pH. It would be appropriate to examine the effect of food density on the migration of phthalic acid esters. Likewise, it would be appropriate to examine the effect of pH but in the same food with different pH on the migration of phthalic acid esters.&nbsp;</p