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The influence of type of ultrafiltration membrane on yoghurt texture produced with ultrafiltrated (UF) milk was investigated. Goat’s milk was concentrated with three membranes of the following pore sizes: 10 kDa, 30 kDa and 100 kDa. Ultrafiltration was carried out to complete 2-fold concentration (v/v) of milk. Concentrated milk was used for production of set yoghurt with Chr. Hansen starter culture YC-180. Yoghurt samples were also produced using unaltered milk. The ultrafiltration process had a significant effect on composition of retentates, sensory evaluation of yoghurts, their viscosity and most of their texture parameters. The type of membrane used influenced significantly dry matter, protein, fat and lactose levels as well as acidity of milk retentates. In consequence sensory evaluation scores, viscosity, hardness and cohesiveness of yoghurt gel were also influenced. The size of membranes had a significant effect on ultrafiltration rate.
The aim of the study was to assess the quality of pastures located in less-favoured areas (LFA) of Czech Republic, to evaluate the influence of that quality on the content of fatty acids of milk in grazing goats and in farm natural cheese made of their milk. Samples of forage were collected in 2008 and 2009, on 5 July, 9 August, 6 September and 4 October. Goat milk samples were taken on the same days of both years and additionally on May 31. The highest content of protein and fat of the forage dry matter and, consequently, the highest feeding value of pasture were found in July and October. It was associated with a high content of clovers and herbs in the available herbage. During grazing the content of saturated fatty acids (SFA) of goat milk fat continuously decreased while the trend for the content of monounsaturated fatty acids (MUFA) was opposite. A significant increase in herb of the total crop observed in autumn contributed to a highest content of polyunsaturated fatty acids (PUFA) in fat of goat milk. The fatty acid profile of goat cheese was related to that of the milk. Thus, a high content of PUFA, including CLA, observed in milk of grazing goats guarantees that the cheese made of that milk fulfills the requirements for functional foods.
This study evaluated the effect of the linearly described shape traits of goat udders on somatic cell count. In a herd of 487 white shorthaired goats, seven traits (udder symmetry, udder depth, udder width, teat length, teat placement, rear udder attachment and udder cleft) were assessed in relation to somatic cell count in milk. The average somatic cell count was 1.3 mill cells/ml when considering the environmental effects (month and year of performance testing, lactation number. The somatic cell count is influenced by the depth (p = 0.0015) and width (p = 0.0268) of the udder. The results demonstrate that some traits of the udder shape influence the somatic cell count and can be considered as functional traits indicating animal health and herd profitability. After further studies, the methodology for linear description of the udder could be used for other dairy goat breeds, not only in the Czech Republic.
A multiresidue method (LC-MS/MS) for determination of wide range of anthelmintics was developed. The method covered benzimidazoles: albendazole (and metabolites), cambendazole, fenbendazol (and metabolites), flubendazole (and metabolites), mebendazole (and metabolites), oxibendazole, thiabendazole (and metabolites), triclabendazole (and metabolites); macrocyclic lactones: abamectin, doramectin, emamectin, eprinomectin, ivermectin, moxidectin; salicylanilides: closantel, ioxynil, nitroxynil, oxyclosamide, niclosamide, rafoxanid and others: clorsulon, derquantel, imidocarb, monepantel (and metabolites), morantel, praziquantel, and pyrantel. The method was used to examine the potential presence of anthelmintics in goat and sheep milk and dairy products from the Polish market. A total of 120 samples of milk, yoghurt, cottage cheese, cream cheese, and curd were analysed. None of the samples were found positive above CCa (1-10 µg/kg) except for one cottage cheese in which traces of albendazole sulfone were detected (5.2 µg/kg) and confirmed. The results of the study showed negligible anthelmintic residues in the goat and sheep milk and dairy products and confirm their good quality.
The objective of the research was to determine the impact of the pasteurization process of raw material and of the type of packaging on the survival rate of probiotic bacteria in bio-yoghurts from goats’ milk during storage. The bio-yoghurts investigated were manufactured from goats’ milk using a container method. The milk under processing was centrifuged and normalized to a fat level of 2%. Next, it was pasteurised at a temperature of 95 °C during 5 min and at 90 °C during 10 min, after which it was cooled to 40 °C. The cooled milk was inoculated with DVS ABT1 inoculants added. The bioyoghurts were thermostated (controlled) in containers at a temperature of 40 °C (+/-1 °C) until they reached a pH level of 4.7. Then, they were cooled again to a temperature below 20 °C and poured into 4 different packagings made of polypropylene (PP), polystyrene (PS), polyethylene (PEHD), and glass (G), each of a capacity of 200 cm³. The bio-yoghurts were subsequently stored in the dark for 21 days at temperatures ranging from 2 to 5 °C. The presence of probiotic bacteria in bio-yoghurt was determined 12 h after the bio-yoghurts were manufactured, and on the 7th, 14th, and 21st day of storage. In total 240 samples were analysed. The applied packagings did not statistically significantly differentiated the count of bacteria in bio-yoghurts manufactured from goats’ milk, except for the Str. thermophilus bacteria count that changed only on the 14th day after manufacturing. The statistically significant impact of the pasteurisation temperature of raw material was found in the case of the L. acidophilus count immediately upon manufacturing. A lower pasteurisation temperature of goats’ milk had a favourable effect on the growth of bacteria, and in such bio-yoghurts the population of all the bacteria was higher. It was found that irrespective of the applied pasteurization temperature of raw material and of the type of packagings, the count of individual bacterial genera was at a level significantly higher than 10⁶ cfu/ml, which ensures that the milk drinks studied achieve the therapeutic minimum. Thus, expanding the production of goat milk bio-drinks can enhance the assortment of healthful diary products available in the market.
The main aim of this study was to evaluate the effect of the lactation stage (SL) on the fatty acids (FA) profile of raw milk of Brown Short-haired goats reared under organic regime. An integraf part of the study was also to assess the effect of the SL on the physico-chemical characteristics and somatic cell count (SCC) of milk. Milk records and samplings of each goat were carried out seven times from April to October. SL had a significant effect on contents of almost all monitored physicochemical properties, somatic cell counts (SCC) and FA of milk and also on average daily milk yield (DMY). DMY gradually decreased with advanced lactation (from 3.44 to 1.44 litre), whereas the content of total solids (TS) increased in the course of lactation (from 10.9 to 14.0%). Also the content of milk fat (F) increased in the course of lactation (from 3.2 to 4.7%). Contents of total protein (TP) and casein (C) were relatively high in early lactation, decreased as lactation peaked and increased towards to late lactation (3.7% of TP and 2.6% of C). Titratable acidity (TA) gradually increased from 90th day (6.2°SH) to the end of lactation (8.5°SH), while positive correlations with TS, F, TP,C and lactose were found. SCC increased as lactation advanced, moreover, a positive correlation among SCC and TA and TS was found. The SL had a significant effect on all FA groups. PUFA gradually decreased towards to late lactation, which was caused mainly by the content of linoleic acid. Similarly, the presence of linolenic acid and PUFA/SFA ratio showed a decreasing tendency with advanced lactation. Also the CLA content was the lowest at the end of lactation. PUFA n-6/n-3 ratio increased in mid lactation (7.8) and hereafter decreased towards to late lactation (3.5). In our opinion, a less favourable presence of particular groups of FA in late lactation was related with a decrease in pasture quality under organic conditions.
A duplex-PCR method, with 2 pairs of primers recognizing sequences of mitochondrial D-loop region, was developed to identify cows’ milk in the milk of goats. The PCR was shown to be specifi c and sensitive, enabling the detection of less than 1% of cows’ milk added to the milk of goats. Simultaneous use of a primer pair for goats’ and cows’ mitochondrial DNA fragment prevented false negative results. The method was applied to track the presence of cow DNA in goat milk available on the Polish market. A total of 54 milk samples from 3 Polish (34) and one foreign producer (20) were examined. In 33 samples, cow DNA was detected, while 21 samples, including all of the 20 samples from foreign producers, produced the goat-specific product only.
The aim of the research project was to assess the quality parameters of goat milk permeate subjected to the fermentation process with the assistance of thermophilic cultures of traditional composition and enriched with probiotic strains. The fermented permeates were stored in refrigerated conditions for 6 weeks and during this period, changes in their active and titratable acidity were estimated, their colour parameters were measured instrumentally and their sensory profiles were examined. The type of the bacterial cultures applied did not affect the pH value of the permeates over the entire storage period. After the termination of the fermentation process, permeates treated with traditional cultures were characterised by the highest titratable acidity and this relationship did not change until the end of the storage period. Regardless of the type of the bacterial culture applied, the fermentation process resulted in a significant decrease of sample L* lightness and increase of their C* colour. After 6 weeks, values of the L* and C* coefficients of the fermented permeates decreased significantly, whereas the non-fermented permeats failed to exhibit any changes in the colour parameters in the course of their storage. The permeate fermented with the assistance of the traditional bacterial culture received the highest number of points for its overall desirability after 6 weeks of storage. During this period, the ‘metallic’ taste of the permeate disappeared and, simultaneously, we could observe an increase in the intensity of a refreshing taste and fresh smell.
Polymorphism of goat milk asrcasein was determined and potential relations between genetic variants of this protein fraction and goat performance were evaluated. The investigations were performed on 598 goats assigned to of 4 breed groups (White improved 254 units, Coloured improved -124, White non-improved - 146 and Coloured non-improved - 74). For each goat, asrcasein polymorphism was determined in Polyacrylamide gel by the PAGE-SDS method and percentage of milk asrcasein and gene frequency established. There was evaluated goat performance at successive lactations. In the goat population investigated, AA, AB, BB, AE, BE and EE αs1-casein genotypes were identified. In all four breeds, αs1-casein genotype EE clearly predominated (27.2-39.2%), recognized as "medium" and its share was higher in the groups of non-improved goats. It was conditioned by high frequency of gene E αs1-casein (0.419-0.622). Generally, EE genotype percentage was higher in the non-improved goat groups. The improved goats, though, obtained higher productivity in each of the lactation studied. Analysis of relationships between αs1-casein genetic variants and goats performance confirmed a significant influence on milk, protein and fat yields only in the Coloured improved goat group. There was revealed a more general tendency indicating a significant impact of "strong" αs1-casein genotypes on a concentration of basic milk components, i.e. fat and protein, especially casein. In a group of goats producing milk of the highest casein content (over 2.4%) and protein (over 3.0%), the animals showing "strong" αs1-casein variants dominated (85 and 70 %).
The study involved the use of Echinapur preparation, containing Echinacea purpurea extract, to promote milk lactoferrin secretion, and – as a result of its antibacterial properties – to reduce inflammatory changes in the goat’s mammary gland. Ten goats with the highest somatic cell count (SCC) of milk were selected from the flock and treated for two weeks with Echinapur. In order to estimate treatment effectiveness, milk was examined for lactoferrin (Lf) concentration, SCC, bacteria counts as colony forming units (CFU) and yield and gross composition of milk, before and at the end of treatment, and then 2 and 4 weeks later. Milk Lf content was determined using the RP-HPLC technique,and milk SCC, CFU and chemical composition were determined instrumentally. Treatment resulted in a transient (P<0.01) decrease of milk protein content below the initial level, compensated by a gradual increase of milk yield (24% over the pre-treatment value). A substantial increase in milk Lf content, with a maximum response (P<0.01) at 2 weeks after the end of treatment, was accompanied by a gradual reduction (P<0.01) in SCC and CFU compared to initial values. This is the first report showing the feasibility of promoting Lf secretion in order to reduce inflammatory changes in the goat mammary gland.
The chemical composition and fatty acid profile of milk from French Alpine dairy goats, obtained during the period of summer feeding and winter feeding, were studied. Milk samples were collected at one-month intervals, to determine dry matter, solids non-fat, protein, fat, fatty acid profile, lactose, urea and somatic cell count. The fatty acid composition of milk fat was determined for particular experimental twice during lactation, i.e. in the middle of the winter season and in the middle of the summer season. It was found that goat’s milk produced in winter had higher levels of dry matter, fat, protein and urea, and a lower lactose content. Goat’s milk obtained over this feeding period had a higher urea content. The somatic cell count recorded in milk from the experimental goats remained within the physiological norms for goat’s milk. The feeding period had a significant effect on the fatty acid profile of goat’s milk. Milk produced in summer had higher levels of unsaturated fatty acids, especially polyunsaturated fatty acids, as well as a more favorable ratio between unsaturated fatty acids and saturated fatty acids, and a lower ratio between monounsaturated fatty acids and polyunsaturated fatty aThe chemical composition and fatty acid profile of milk from French Alpine dairy goats, obtained during the period of summer feeding and winter feeding, were studied. Milk samples were collected at one-month intervals, to determine dry matter, solids non-fat, protein, fat, fatty acid profile, lactose, urea and somatic cell count. The fatty acid composition of milk fat was determined for particular experimental twice during lactation, i.e. in the middle of the winter season and in the middle of the summer season. It was found that goat’s milk produced in winter had higher levels of dry matter, fat, protein and urea, and a lower lactose content. Goat’s milk obtained over this feeding period had a higher urea content. The somatic cell count recorded in milk from the experimental goats remained within the physiological norms for goat’s milk. The feeding period had a significant effect on the fatty acid profile of goat’s milk. Milk produced in summer had higher levels of unsaturated fatty acids, especially polyunsaturated fatty acids, as well as a more favorable ratio between unsaturated fatty acids and saturated fatty acids, and a lower ratio between monounsaturated fatty acids and polyunsaturated fatty acids. Goat’s milk obtained over this period had higher concentrations of linoleic acid (C18:2), linolenic acid (C18:3) and conjugated dienes of linoleic acid.
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