Template-Type: ReDIF-Article 1.0
Author-Name: I. Bohačenko
Author-Name: Z. Veselý
Title: Proof of authenticity of pure instant coffee
Abstract: An HPLC method with refractometric detection was worked out for the determination of the limiting contents of marker saccharides (free mannitol and total glucose and xylose) used for the proof of authenticity of pure instant coffee. This method, even though more laborious, yields results comparable with those obtained by the HPAE-PAD method and is intended mainly for those laboratories where the current HPLC technique with refractometric detection is presently used for saccharide analysis. The survey of market supply showed that instant coffee imported in bulk and subsequently packaged in the Czech Republic is most frequently adulterated - only one out of 7 samples examined contained authentic coffee. On the other hand, only one out of 10 samples of instant coffee imported in original packaging did not meet the authenticity criteria. The samples of instant coffee by domestic producers indicated that one producer placed on the market an adulterated product, whereas the other brand is authentic coffee.
Keywords: instant coffee, authenticity, adulteration, HPLC with RI detection
Journal: Czech Journal of Food Sciences
Pages: 165-169
Volume: 18
Issue: 5
Year: 2000
DOI: 10.17221/8337-CJFS
File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8337-CJFS.html
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Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:5:id:8337-CJFS

Template-Type: ReDIF-Article 1.0
Author-Name: P. Navrátilová
Title: Pathogenic micro-organisms in waste waters from daiies
Abstract: Waste waters from dairies were tested for the presence of bacterial pathogens - Listeria monocytogenes, Staphylococcus aureus and Salmonella spp. The prevalence of bacteria was investigated in each stage of the cleaning process (activated sludges systems) too. Two hunder samples of raw waste water, activated sludge, returned activated sludge, excess sludge and treated water from 14 dairies were tested. The samples were all negative for Salmonella spp. From a total of 102 (51%) strains Listeria spp., Listeria inoccua 95 (47.5%) and Listeria monocytogenes 7 (3.5%) were identified. 47 samples were positive for S. aureus. L. monocytogenes were detected in raw waste water 1 (1.6%), in activated sludge 3 (5.5%), in excess sludge 1 and in treated water 2 (3.1%). S. aureus were detected in raw waste water 14 (22.6%), in activated sludge 23 (41.8%), in excess sludge 1 and in treated water 8 (12.3%). These results demonstrate a prevalence of L. monocytogenes and S. aureus in waste waters from dairies. During the cleaning process pathogenic bacteria were not devitalized. The excess sludge and treated water including pathogenic micro-organisms represent a potential health hazard.
Keywords: pathogens, waste water, sludge, dairy
Journal: Czech Journal of Food Sciences
Pages: 170-174
Volume: 18
Issue: 5
Year: 2000
DOI: 10.17221/8338-CJFS
File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8338-CJFS.html
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Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:5:id:8338-CJFS

Template-Type: ReDIF-Article 1.0
Author-Name: M. Vyletělová
Author-Name: J. Ficnar
Author-Name: O. Hanuš
Title: Effects of lipolytic enzymes Pseudomonas fluorescens on liberation of fatty acids from milk fat
Abstract: Effects of thermostable lipolytic enzymes Pseudomonas fluorescens 66 ZB in pasteurized milk on concentration of free fatty acids (VMK) in milk were studied in selected milk samples. Identical bulk milk samples were analysed by the method specified in previous papers (Vyletělová et al. 1999a, b, 2000). Reference milk samples (without bacterial strains) and the experimental ones (containing Ps. fl. 150 th. CFU/ml and 2800 th. CFU/ml, resp.) were stored at 6.5°C and 14°C and analysed at regular time intervals (24 h) - Table 1. An extractive-titric method (Kadlec et al. 1996; Table 2 and Fig. 2) was used for monitoring of fatty acid (MK) liberation. Precise analyses of MK and VMK were made by the chromatographic method (Figs. 1, 3 and 4). Medium-chain fatty acids (C12-C16) are liberated first of all; short-chain acids (C6-C10) were found sporadically or in very small quantities (Table 2). Dissociation constant of the specific fatty acid liberated from milk fat affects principally relationships between pH and free fatty acid concentration. The predominating proportion of long-chain acids in liberated fatty acid formation is associated with lower reduction of pH as compared to the predomination of fatty acids with shorter chains associated with more substantial reduction of pH. In our study, a rapid decrease of pH was noted before 168 h (Table 24); this corresponds to low concentrations of short-chain free fatty acids. Vyletělová et al. (2000) found significant relations between pH and contents of VMK (measured by the extractive-titric method); in some samples, correlation coefficients amounted to r = -0.93*** (P ≤ 0.001). The extractive-titric method analysing VMK concentrations (mmol/kg milk fat) provides results characterized by a systematic rise (e.g., 32.0 mmol/kg instead of 13.0 mmol/kg in raw milk). According to Kratochvíl (1992) 20 mmol VMK/kg milk fat signalized the starting point characterizing flavour degradation of milk caused by activities of fatty acids C12-C14 above all; the transformed value (respecting specifics of the extractive-titric method) amounts to 49 mmol/kg. In case of higher storage temperature a significant break is found after 144 h; in case of lower temperature this break is after 192 h (Table 2). Limits determining potential lipolytic modifications of milk flavour (RLZCHV) as related to specific samples and temperatures at VMK levels amounting to 49 mmol/kg or 20 mmol/kg are outlined in Fig. 2. Milk samples No. 5 and No. 6 stored at higher temperature surpassed this risk limit at 56 h and 64 h, respectively (Table 2, Fig. 2). On the contrary, milk samples stored temperatures corresponding to the standard storage temperature (storage of raw milk, transport, storage of pasteurized milk) surpass the mentioned risk level after 90 h and 140.5 h. Obtained results document the predominant role of storage temperature in the whole complex (production and processing of milk as a raw material or an intermediate product); evident differences in contamination rates (105 an 106) can be characterized as secondary effects in this case (Table 2). As related to practical conditions, the mentioned facts imply immediate processing of raw milk and pasteurized milk. This postulate must be respected namely by dairy plants producing delicate milk products. Vyletělová et al. (2000) found a notable VMK increase/24 h (7-11 mmol/kg milk fat) under specific temperatures and microbial contamination.
Keywords: milk, Pseudomonas fluorescens, lipolytic enzymes, free fatty acids, extractive-titric method, chromatographic method
Journal: Czech Journal of Food Sciences
Pages: 175-182
Volume: 18
Issue: 5
Year: 2000
DOI: 10.17221/8339-CJFS
File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8339-CJFS.html
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Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:5:id:8339-CJFS

Template-Type: ReDIF-Article 1.0
Author-Name: A. Landfeld
Author-Name: M. R Karpíšková Houška
Author-Name: K. Kýhos
Author-Name: P. Novotná
Title: Verification of prediction of growth of Listeria monocytogenes micro-organism in chicken meat
Abstract: Raw chicken meat was comminuted and homogenised. There were measured water activity and pH (aw = 1 for temperature 25°C, pH = 5.8 for temperature 8°C). Input raw material was investigated for the presence of Listeria monocytogenes (negative) and the raw meat was inoculated by Listeria monocytogenes CCM 4699. Number of Listeria monocytogenes, total plate count and number of coliforms were determined in the range 0-7 days by bacteriological survey for the storage temperatures 4.9, 7 and 8.3°C. The increase of Listeria monocytogenes counts has been registered for temperature 4.9°C about log 1.5 CFU/g after 6 days, for temperatures 7 and 8.3°C about 2 log CFU/g (regarding to the starting counts). The prediction for listeria growth with the aid of Food MicroModel was also made. The best agreement between the experimentally analysed number of bacteria and prediction was received for the lowest incubation temperature 4.9°C.
Keywords: micro-organism, Listeria monocytogenes, chicken meat, Food Micromodel verification
Journal: Czech Journal of Food Sciences
Pages: 183-186
Volume: 18
Issue: 5
Year: 2000
DOI: 10.17221/8340-CJFS
File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8340-CJFS.html
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Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:5:id:8340-CJFS

Template-Type: ReDIF-Article 1.0
Author-Name: J. Strohalm
Author-Name: H. Valentová
Author-Name: M. Houška
Author-Name: P. Novotná
Author-Name: A. Landfeld
Author-Name: K. Kýhos
Author-Name: R. Grée
Title: Changes in quality of natural orange juice pasteurised by high pressure during storage
Abstract: Natural orange juice pasteurised (pascalised) by high pressure was stored for 180 days at room temperature in dark conditions. Sensory evaluation of several quality parameters was made. At the same time the frozen and heat pasteurised parallel samples of the juice of the same origin were evaluated for comparison. The sensory evaluation consists of overall image, flavour, taste and sensorial viscosity. The instrumental evaluation of colour, pH and kinematic viscosity was made. The best overall image was received for frozen juice. The pressurised and heated samples were nearly the same as regards the flavour. The sensorial viscosity of all samples was evaluated as thin with very small differences during storage. The preference test was also made - the best quality for the test panel was received for samples of frozen juice followed by pressurised juice. The third rank was given to heat treated samples. The pressurised samples exhibited the acceptable quality for 150 days of storage at room temperature.
Keywords: orange juice, pasteurisation, high pressure, freezing, storage, sensory and instrumental evaluation, viscosity, colour, pH
Journal: Czech Journal of Food Sciences
Pages: 187-193
Volume: 18
Issue: 5
Year: 2000
DOI: 10.17221/8341-CJFS
File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8341-CJFS.html
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Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:5:id:8341-CJFS

Template-Type: ReDIF-Article 1.0
Author-Name: K. Hoke
Author-Name: L. Klíma
Author-Name: R. Grée
Author-Name: M. Houška
Title: Controlled thawing of foods
Abstract: The various ways of thawing of model food made for comparison of these processes from point of view of duration. The experiments were conducted under condition that the surface temperature of the thawed food did not overcome 15°C. Shortest mean time of thawing was achieved for vacuum-steam thawing. Regarding to the regime chosen the time of thawing varied between 18.4-29 min. The similar process of vacuum thawing with steam generated from hot water placed below the food was also successful. For this process the mean time of thawing was predicted between 30.5 and 35 min. If the starting temperature of the water was below the boiling point at vacuum level in the chamber the time of thawing was much longer (about 49 min). For hot air thawing we have tested two regimes with temperature of air 50 and 70°C. For both air temperatures the times of thawing were similar being 52.1 and 53.6 min, respectively. Microwave thawing was depending on the power of microwave oven. The time of thawing was achieved 28.9 min at power level 1, at power level "thawing" the process duration was 34.4 min.
Keywords: thawing, steam-vacuum thawing, hot air thawing, microwave heating
Journal: Czech Journal of Food Sciences
Pages: 194-200
Volume: 18
Issue: 5
Year: 2000
DOI: 10.17221/8342-CJFS
File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8342-CJFS.html
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Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:5:id:8342-CJFS

Template-Type: ReDIF-Article 1.0
Author-Name: P. Kalač
Author-Name: J. Moudrý
Title: Composition and nutritional value of amaranth seeds
Abstract: There are reviewed literature data on proteins, lipids, starch, oligosaccharides, dietary fibre, mineral constituents, vitamins and antinutritional compounds of amaranth seeds. Moreov r, information on isolation of squalene from oil and betacyanin pigments from leaves and inflorescence is given. Data on hypocholesterolemic effect of amaranth seeds are also mentioned.
Keywords: Amaranthus spp., amaranth seeds, composition, nutritional value, review article
Journal: Czech Journal of Food Sciences
Pages: 201-206
Volume: 18
Issue: 5
Year: 2000
DOI: 10.17221/9651-CJFS
File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/9651-CJFS.html
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Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:5:id:9651-CJFS

Template-Type: ReDIF-Article 1.0
Author-Name: B. Hozová
Author-Name: M. Grejtáková
Title: The properties and quality of goat and sheep milk and its products - a review
Abstract: The newer knowledge from the field of the quality evaluation of goat and sheep milk and milk products are reviewed in this paper. The negative influence of microbial and chemical contamination and methods of determination are described. The significance of monitoring of the conditions (pasteurization, hygienic control) to ensure public health are accented. Quality standards adjusted for the specifics of goat/sheep milk should be considered.
Keywords: goat and sheep milk, nutrition, composition, bacterial and chemical contamination, quality control
Journal: Czech Journal of Food Sciences
Pages: 207-211
Volume: 18
Issue: 5
Year: 2000
DOI: 10.17221/8343-CJFS
File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8343-CJFS.html
File-Format: text/html
Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:5:id:8343-CJFS