Chilled Samples Research Articles

Predicting liquid loss of frozen and thawed cod from hyperspectral imaging

As the ability to appraise the quality of every fish in a delivery in a consistent, objective, and rapid manner has numerous advantages for both sellers and buyers, there has been much research into methods to achieve this. One possible proxy for quality assessment is liquid loss, which correlates with undesirable sensory attributes. This study evaluated whether hyperspectral imaging could predict liquid loss on samples that had undergone a program of freezing and thawing. Vacuum-packaged cod loins were split into two groups, one which was kept chilled and the other that underwent a program of freezing and thawing. Multivariate analysis of the hyperspectral imaging data on the chilled samples could predict liquid loss with good accuracy for samples that underwent no further processing. Analysis of data from the hyperspectral images of the frozen and thawed cod samples also showed a good ability to predict their liquid loss. These results indicate that hyperspectral imaging is a promising method for non-invasive quality monitoring of cod products in different processing states. Also, whereas previous research had been unable to predict sample processing protocols, improvements to the hyperspectral imaging technology now enables identification of samples based on freezing and thawing procedures.

Two IncHI2 Plasmid-Mediated Colistin-Resistant Escherichia coli Strains from the Broiler Chicken Supply Chain in Zhejiang Province, China

Colistin is used as one of the last-resort drugs against lethal infections caused by carbapenem-resistant pathogens of the Enterobacteriaceae family. Enterobacteriaceae bacteria carrying the mcr-1 colistin resistance gene are emerging in livestock and poultry, posing a serious threat to human health. However, there have been few reports about the prevalence and transmission of mcr-1 along the regional chicken supply chain. In this study, the complete sequences of mcr-1-positive Escherichia coli ST2705 and ST206 isolates obtained by screening 129 chilled chicken samples and 251 chicken fecal samples were investigated. Both of these isolates showed resistance to colistin, and importantly, the complete sequence of the mcr-1-positive E. coli ST2705 in China was reported for the first time. The mcr-1 gene was located on the IncHI2 plasmids pTBMCR421 (254,365 bp) and pTBMCR401 (230,964 bp) in strains ECCNB20-2 and ECZP248, respectively. Comparative analysis of mcr-1-bearing IncHI2 plasmids showed a marked similarity, indicating that these plasmids are very common and have the ability to be efficient vehicles for mcr-1 dissemination among humans, animals, and food. Furthermore, an insertion (ISKpn26) in Tn6330 (ISApl1-mcr-1-pap2-ISApl1) was identified in the plasmid pTBMCR401 and then compared; this insertion might affect the adaptability and stability of Tn6330. Taken together, these findings suggest that the IncHI2 plasmid might be a main factor affecting the transmission of mcr-1 in the chicken supply chain and that the genetic context of the mcr-1-bearing IncHI2 plasmid is constantly evolving.

Gravading process of Nile tilapia ( Oreochromis niloticus ) and evaluation of its biochemical and sensory changes during refrigerated storage

Gravads were prepared from Nile tilapia (Oreochromis niloticus) and evaluated its shelf life during chilled (6°C) and iced (0°C) storage. For standardizing the gravading process, different salt:sugar combinations of gravad mix and two steaks to gravad mixture ratio (1:0.1 and 1:0.2) were selected. Gravads prepared using 1:2 salt-sugar in the gravad mix and a ratio of 1:0.1 steaks to gravad mix was found optimum combination. Gravads prepared using the standardized combination of salt and sugar were stored at 0°C and 6°C and evaluated for its biochemical and sensorial changes. Total volatile base nitrogen (TVB-N) increased from 10.25 mg/100 g to 29.85 and 30.66 mg/100 g on Day 41 and Day 49 for chilled and iced samples, respectively. The extend of secondary oxidation was low in both samples, registering an increase from 0.14 mg MDA/kg sample to 0.814 and 0.851 MDA/kg sample on 41st and 49th day, respectively, for chilled and iced samples. Water soluble and salt soluble nitrogen contents were reduced to 1.82 and 5.47 mg/100 g and 1.58 and 4.72 mg/100 g by the end of 41st and 49th day, respectively, for chilled and ice stored gravads. The shelf life of gravads was determined as 41 days under chilled storage and 45 days under iced storage. Practical applications Nile tilapia is widely cultured fish species in India after the Indian major carps. It is of great interest to the farmers and demand among the consumers because of its fast growth rate and good meat quality. Value addition is an effective approach to utilize this resource cost-effectively during excessive production periods. Conversion of Nile tilapia into gravads not only increases the value but also enhances the quality and shelf life of the product. The results of the present study provide an idea of appropriate process parameters for making gravads from Nile tilapia and information on its shelf life under refrigerated storage.

Effect of preparation of the test samples by dissolution on the indicators of the protein composition of animal meat

The article presents the research of the protein composition of meat of wild animals (elk and wild boar) and domestic animals (beef), by their isolation and separation methods due to their different solubility in different solutions, conducted in the laboratory of Biological Safety of Food Systems of the Department of Meat and Dairy Products Technology of Mari State University. The total proteins or protein fractions were extracted from a homogenized chilled meat sample. Then, the colorless proteins in the extract were transferred to the colored product, adding a biuret reagent, and studied the D optical density of separate protein fractions on the photoelectric concentration colorimeter PCC-2, determining the absorption of emitting at a wavelength of 540 nm. The protein content of the samples was expressed in the mass fraction of the protein fraction in the sample in g/ 100g of meat and in percentages. The calculation was based on the previously found linear calibration dependence of the optical density on the concentration of the standard protein. Using sequential extraction of muscle proteins with water, saline and alkaline it is possible to obtain different protein fractions. Differentiation of proteins by solubility (water-soluble, soluble in salts, alkaline-soluble, albumins, globulins), fractional composition (sarcoplasmic, myofibrillar and connective tissue), peculiarities of the biochemical structure (high-grade and inferior). Protein extracts of muscle tissue of wild and domestic animals obtained during sequential extraction are used to quantify the protein content of a certain fraction, as well as to research the properties of proteins.

Effect of preparation of the test samples by dissolution on the indicators of the protein composition of animal meat

The article presents the research of the protein composition of meat of wild animals (elk and wild boar) and domestic animals (beef), by their isolation and separation methods due to their different solubility in different solutions, conducted in the laboratory of Biological Safety of Food Systems of the Department of Meat and Dairy Products Technology of Mari State University. The total proteins or protein fractions were extracted from a homogenized chilled meat sample. Then, the colorless proteins in the extract were transferred to the colored product, adding a biuret reagent, and studied the D optical density of separate protein fractions on the photoelectric concentration colorimeter PCC-2, determining the absorption of emitting at a wavelength of 540 nm. The protein content of the samples was expressed in the mass fraction of the protein fraction in the sample in g/ 100g of meat and in percentages. The calculation was based on the previously found linear calibration dependence of the optical density on the concentration of the standard protein. Using sequential extraction of muscle proteins with water, saline and alkaline it is possible to obtain different protein fractions. Differentiation of proteins by solubility (water-soluble, soluble in salts, alkaline-soluble, albumins, globulins), fractional composition (sarcoplasmic, myo????ibrillar and connective tissue), peculiarities of the biochemical structure (high-grade and inferior). Protein extracts of muscle tissue of wild and domestic animals obtained during sequential extraction are used to quantify the protein content of a certain fraction, as well as to research the properties of proteins.

Transcriptome analysis of postharvest blueberries (Vaccinium corymbosum \u2018Duke\u2019) in response to cold stress

BackgroundBlueberry (Vaccinium spp.) is a small berry with high economic value. Although cold storage can extend the storage time of blueberry to more than 60 days, it leads to chilling injury (CI) displaying as pedicle pits; and the samples of 0 °C-30 days was the critical point of CI. However, little is known about the mechanism and the molecular basis response to cold stress in blueberry have not been explained definitely. To comprehensively reveal the CI mechanisms in response to cold stress, we performed high-throughput RNA Seq analysis to investigate the gene regulation network in 0d (control) and 30d chilled blueberry. At the same time, the pitting and decay rate, electrolyte leakage (EL), malondialdehyde (MDA) proline content and GSH content were measured.ResultsTwo cDNA libraries from 0d (control) and 30d chilled samples were constructed and sequenced, generating a total of 35,060 unigenes with an N50 length of 1348 bp. Of these, 1852 were differentially expressed, with 1167 upregulated and 685 downregulated. Forty-five cold-induced transcription factor (TF) families containing 1023 TFs were identified. The DEGs indicated biological processes such as stress responses; cell wall metabolism; abscisic acid, gibberellin, membrane lipid, energy metabolism, cellular components, and molecular functions were significantly responsed to cold storage. The transcriptional level of 40 DEGs were verified by qRT-PCR.ConclusionsThe postharvest cold storage leads serious CI in blueberry, which substantially decreases the quality, storability and consumer acceptance. The MDA content, proline content, EL increased and the GSH content decreased in this chilled process. The biological processes such as stress responses, hormone metabolic processes were significantly affected by CI. Overall, the results obtained here are valuable for preventing CI under cold storage and could help to perfect the lack of the genetic information of non-model plant species.

Evaluation of the Reduction of Escherichia coli O157:H7 Surrogates in Beef Ribeye Rolls at 54.4°C

ObjectivesE. coli infections are a primary source of gastroenteritis requiring strict cooking and handling procedures for meat producing companies as directed by the USDA. This study evaluated the reduction of Escherichia coli O157:H7 surrogates in a low temperature cook process at a local medium-large meat processor. This is one of three microbial validation projects; the other projects will investigate Clostidium perfrigens and Salmonella spp. The objective of maintaining meat quality (rare color) throughout cooking processes urges the study of low temperature cook processes to determine their efficacy in microbial control.Materials and MethodsThis study was completed in three replications each consisting of a sample size of n = 25. Four strains of Escherichia coli (American Type Culture Collection, ATCC® BAA-1427, 1428, 1429, and 1431), each approved as a surrogate for E. coli O157:H7, were used in this study. Each surrogate was grown separately. Inoculations of surrogates were prepared utilizing 800 mL of distilled water mixed with 24 g of TSB and inoculated with surrogates. The inoculations were incubated at 37°C for 24 h prior to application. The surrogates were mixed together to make a cocktail just prior to inoculation of meat. Seventy-five (25 per replication) ribeye rolls (IMPS 112-A) were removed from vacuum bags and trimmed. Initial samples were taken to determine initial microbial load prior to inoculation. The pH and temperature were taken in raw meat, after spraying with antimicrobial, and after brining. The pH and temperature of the brine was also recorded. Meat was inoculated with 90 mL of inoculum and was distributed evenly on the surface with a sponge on a stick. The inoculum was allowed to dry for 30 min prior to sampling for inoculation load. Ribeye rolls were then sampled 15 min after going through an antimicrobial spray. Samples for raw meat, initial inoculated meat, and after antimicrobial spray were taken from the surface of the ribeye roll (approximately 100 g). Following sampling, the ribeye rolls were pumped with a brine solution (sugar, salt, and proprietary ingredients) to 15%. The meat was vacuum-packaged in cook-in bags and allowed to sit in a cooler to mimic the longest period of time from packaging until it would be placed in the smokehouse. Ribeye rolls were cooked according to Appendix A at 54.4°C for 112 min, and chilled until the internal temperature was below 4.4°C. Final cooked and chilled samples were taken by cutting a 4 cm steak from the center of the roast. All samples were packaged and sent to Food Safety Net Services (FSNS) for culturing on coliform film. At FSNS 25 g of meat and 225 mL of BPW were stomached, serial dilutions were done and plated on coliform petrifilm and allowed to incubate for 24–48 h. Results were analyzed using the proc GLM procedure of SAS, determining the LSMean and StdError as well as Microsoft Excel.ResultsInitial inoculation loads after inoculation were 6.5 logs and all cooked and chilled samples had less than 1 log. Therefore, the mean log reduction was 5.1 with a standard error of 0.04 from inoculation to post-cook over the three replications.ConclusionThe results suggest that this cook method is sufficient to reduce E. coli O157:H7 in whole-muscle beef ribeye rolls. This information would be beneficial to companies looking to preserve meat quality while utilizing a low temperature cook process.

Ex vivo comparison of the effect of storage temperature on canine intestinal leakage pressures.

To determine the effect of storage temperature on cadaveric small intestinal leakage pressures after enterotomy. Experimental ex vivo study. Grossly normal jejunal segments from four canine cadavers. Thirty-six jejunal segments (n = 12 segments/group) were harvested immediately after euthanasia and assigned to a fresh group (tested within 4 hours), chilled group (stored for 24 hours at 4°C before testing), or freeze-thaw group (frozen at -20°C for 7 days and thawed at 21°C for 6 hours before testing). A 2-cm antimesenteric enterotomy was performed and repaired with 4-0 monofilament suture in a simple-continuous pattern. Initial leakage pressure (ILP), maximal intraluminal pressure (MIP), and leakage location were recorded, with testing performed at room temperature. Mean ± SD ILP for fresh, chilled, and frozen-thawed specimens was 52.9 ± 8.4, 51.8 ± 11.9 and 29.8 ± 4.4 mm Hg, respectively. There was a difference in ILP among groups (P < .003), with freeze-thaw samples demonstrating lower ILP compared with other groups. There was no difference in MIP between groups (P = .186) There was a difference in leakage location among groups (P = .004), with the majority of chilled and freeze-thaw samples leaking at the suture holes compared with the incisional line in fresh samples. Freezing and subsequent thawing prior to specimen testing reduced ILP compared with use of fresh and chilled specimens but did not affect MIP among experimental groups. Cadaveric canine intestinal specimens tested immediately after collection or after chilling for 24 hours should be recommended for ex vivo burst pressure assessment in dogs. Additional studies to evaluate loss in testing viability of chilled intestinal specimens are warranted to help govern experimental methodologies.

Mycological Assessment of Marketed Duck Meat in El-Kaliobia Governorate Markets

This study was conducted to evaluate the mycological contamination of duck carcasses, and its hazards on public health. A total of two hundred meat samples of duck meat were taken from chilled and frozen breast and thigh (100 of each) that were collected from supermarkets in El- Kaliobia governorate for mycological examination. The mean values of yeast and mold count of the examined chilled samples were 3.1×102 ±0.02×10 (cfu/g) and 5.5 ×102 ±0.4×10 (cfu/g) in breast and thigh, respectively. Also, those frozen samples had mean values of 3.0×102 ±0.3×10 (cfu/g) and 6.0×102± 0.4×10 (cfu/g) for breast and thigh, respectively. PCR ampilication was resulted in (3) toxigenic strains of A.flavus, A.fumigatus and A.niger were isolated from examined samples. Aflatoxin residues were detected in breast and thigh of 0.26 and 0.33 ng/g. Thus, strict hygienic precautions during processing of duck products should be adopted to reduce mold contamination and mycotoxin production .

Measuring citrate synthase activity as an enzymatic approach to the differentiation of chilled and frozen/thawed meat

Citrate synthase belongs between mitochondrial enzymes which are released from the meat tissue after cell membrane damage caused by ice crystal formation. The presence of this enzyme can indicate a previous freezing process. In this study, we determined citrate synthase activity for chilled and frozen/thawed meats (chicken, pork, beef, and salmon). As an additional factor, we examined a potential connection between microbial spoilage and increased enzyme activity. UV spectrophotometry was used for the evaluation of the citrate synthase activity. The effect of microbial spoilage on the enzyme activity was established through microbial analysis, which was carried out for two weeks for chilled and five months for frozen/thawed meats. The citrate synthase activity in the frozen/thawed samples was significantly higher than in the chilled samples. Dependence of microbial contamination and the increased activity of the citrate synthase was not observed. Our results suggest that there could be designed specific limits of citrate synthase activity for the resolution of chilled and frozen/thawed meats.

Effects of supplementation of Tris-egg yolk extender with royal jelly on chilled and frozen-thawed ram semen characteristics

This study was conducted to examine the effect of supplementation of Tris-egg yolk extender with lyophilized royal jelly (RJ) on chilled and frozen-thawed ram semen parameters. Ejaculates were collected by artificial vagina from 4 mature rams, twice a week for 4 weeks. Only samples with motility of ≥70% were included, pooled and divided into four equal parts and then diluted in extenders with various concentrations of RJ (0, 1, 3 and 5%, vol/vol) to a final concentration of 200 × 106 sperm/mL and was incubated at 37 °C for 30 min and were subsequently evaluated. After equilibration of extended semen for 2 h at 4 °C, some semen samples were packed in 0.25 mL plastic straws. Then, the straws were frozen in the liquid nitrogen vapor phase for 15 min and stored at −196 °C in liquid nitrogen. The frozen straws were thawed in warm water (37 °C) for 30 s and evaluated; whereas, other semen samples were stored in the refrigerator (4 °C) up to 7 days. The chilled samples were kept in water bath (37 °C) for 5 min and then were evaluated. After dilution, the lowest and highest sperm total abnormality was recorded in 3 and 5% RJ supplemented groups, respectively (P < 0.05). The chilled sperm total motility and membrane integrity were significantly (P < 0.05) higher in 3% than those in 0% and 5% RJ supplemented groups. The chilled sperm progressive motility and viability was significantly (P < 0.05) higher in 1 and 3% than those in 0 and 5% RJ supplemented groups. The frozen-thawed sperm total motility, progressive motility, membrane integrity and viability were significantly higher in 3% RJ supplemented group (P < 0.05). In conclusion, supplementation of Tris-egg yolk extender with 3% lyophilized RJ had a protective effect on chilled and cryopreserved ram spermatozoa.

Superchilled, chilled and frozen storage of Atlantic mackerel (Scomber scombrus) fillets – changes in texture, drip loss, protein solubility and oxidation

SummaryChanges in quality characteristics in relation to protease activity and protein oxidation in chilled, superchilled and frozen mackerel fillets during storage were studied. The solubility of sarcoplasmic proteins was quite stable in mackerel samples for all storage experiments, whereas the solubility of myofibrillar proteins decreased in both superchilled and frozen samples. A significant correlation (r = 0.983, P &lt; 0.05) between the increased activity of cathepsin B+L in chilled fillets and softening of the fish flesh during storage was revealed. Contrary with chilled samples, the texture of superchilled mackerel fillets became tougher along the storage period, which can be explained by a higher rate of myofibrillar oxidation (r = 0.940, P &lt; 0.05). The hardness and drip loss decreased slightly at the end of frozen storage. Superchilling preserved the quality of mackerel fillets with the least side effects in relation to protein solubility, drip loss and softening of the fish tissue as compared to chilled and frozen storage.

Evaluation of the Reduction of Escherichia coli O157:H7 Surrogates in Beef Ribeye Rolls at 54.4°C

ObjectivesE. coli infections are a primary source of gastroenteritis requiring strict cooking and handling procedures for meat producing companies as directed by the USDA. This study evaluated the reduction of Escherichia coli O157:H7 surrogates in a low temperature cook process at a local medium-large meat processor. This is one of three microbial validation projects; the other projects will investigate Clostidium perfrigens and Salmonella spp. The objective of maintaining meat quality (rare color) throughout cooking processes urges the study of low temperature cook processes to determine their efficacy in microbial control.Materials and MethodsThis study was completed in three replications each consisting of a sample size of n = 25. Four strains of Escherichia coli (American Type Culture Collection, ATCC® BAA-1427, 1428, 1429, and 1431), each approved as a surrogate for E. coli O157:H7, were used in this study. Each surrogate was grown separately. Inoculations of surrogates were prepared utilizing 800 mL of distilled water mixed with 24 g of TSB and inoculated with surrogates. The inoculations were incubated at 37°C for 24 h prior to application. The surrogates were mixed together to make a cocktail just prior to inoculation of meat. Seventy-five (25 per replication) ribeye rolls (IMPS 112-A) were removed from vacuum bags and trimmed. Initial samples were taken to determine initial microbial load prior to inoculation. The pH and temperature were taken in raw meat, after spraying with antimicrobial, and after brining. The pH and temperature of the brine was also recorded. Meat was inoculated with 90 mL of inoculum and was distributed evenly on the surface with a sponge on a stick. The inoculum was allowed to dry for 30 min prior to sampling for inoculation load. Ribeye rolls were then sampled 15 min after going through an antimicrobial spray. Samples for raw meat, initial inoculated meat, and after antimicrobial spray were taken from the surface of the ribeye roll (approximately 100 g). Following sampling, the ribeye rolls were pumped with a brine solution (sugar, salt, and proprietary ingredients) to 15%. The meat was vacuum-packaged in cook-in bags and allowed to sit in a cooler to mimic the longest period of time from packaging until it would be placed in the smokehouse. Ribeye rolls were cooked according to Appendix A at 54.4°C for 112 min, and chilled until the internal temperature was below 4.4°C. Final cooked and chilled samples were taken by cutting a 4 cm steak from the center of the roast. All samples were packaged and sent to Food Safety Net Services (FSNS) for culturing on coliform film. At FSNS 25 g of meat and 225 mL of BPW were stomached, serial dilutions were done and plated on coliform petrifilm and allowed to incubate for 24–48 h. Results were analyzed using the proc GLM procedure of SAS, determining the LSMean and StdError as well as Microsoft Excel.ResultsInitial inoculation loads after inoculation were 6.5 logs and all cooked and chilled samples had less than 1 log. Therefore, the mean log reduction was 5.1 with a standard error of 0.04 from inoculation to post-cook over the three replications.ConclusionThe results suggest that this cook method is sufficient to reduce E. coli O157:H7 in whole-muscle beef ribeye rolls. This information would be beneficial to companies looking to preserve meat quality while utilizing a low temperature cook process.

Systematic study of the quality and safety of chilled pork from wet markets, supermarkets, and online markets in China.

With increasing media coverage of food safety incidents, such as that of clenbuterol residues in pork, food safety has become a major public health concern in China. Rapidly developing online markets attract increasing numbers of Chinese consumers to purchase food on the Internet. However, the quality and safety of food sold online are uncertain and are less reported on. This research aimed to systematically study the quality and safety of chilled pork from wet markets, supermarkets, and online markets in China. The chilled pork samples from online markets were fresher than those from wet markets and supermarkets based on the surface redness (a* value). Chilled pork contained high levels of nutritional elements, especially the magnesium and phosphorus levels in samples from online markets. The levels of heavy metal element residues and veterinary drug residues in all chilled pork samples were within the standards limits. In addition, huge differences existed in the quality and freshness of the chilled pork samples from online markets according to principal component analysis (PCA). Most chilled pork sold in Chinese markets was qualified and safe. It is necessary to establish an effective online market supervision system for chilled pork.

Changes in the Quality of Chicken Breast Meat due to Superchilling and Temperature Fluctuations during Storage.

The aim of this study was to determine the changes in chicken breast meat quality (water-holding capacity, color, texture, myofibrillar fragmentation index (MFI), total protein solubility, thiobarbituric acid reactive substances (TBARS), total viable count (TVC), and lactic acid bacteria (LAB) count) due to storage under superchilling conditions (−1.3°C) and fluctuating temperatures (ranging from −20°C to −5°C) as compared to the quality of meat stored at chilled (2–4°C) and frozen (−20°C) temperatures, respectively. Results indicated that the TVC and LAB count of the chilled and superchilled breast meat increased with storage time. TVC of the chilled and superchilled breast meat reached the safety level of 7 log cfu/g at approximately day 8 and18, respectively. This suggested that the superchilling method extended the storage duration by 10 days. Weight loss and TBARS of the chilled and superchilled samples tended to increase with increasing storage time. The color, texture, protein solubility, and MFI were stable throughout the entire storage period of the chilled (9 days) and superchilled (28 days) samples. Results indicated that while three cycles of storage temperature fluctuation influenced the weight loss and dry matter of the meat, they did not affect the TVC, LAB count, texture, color, pH, MFI, and protein solubility. The superchilling technique (−1.3°C) could extend the shelf-life of meat and maintain the quality of chicken breast meat. Fluctuations in temperature during frozen storage decreased the water-holding capacity of chicken breast meat, indicating that temperature stability should be maintained during frozen storage.

Effect of reduced glutathione (GSH) supplementation to Tris-egg yolk extender on chilled semen variables of dogs

One reason for reduced longevity of chilled dog semen is oxidative stress. The antioxidant glutathione (GSH) improves viability of frozen-thawed dog sperm, but its effect on chilled dog semen has not been investigated. An experiment consisting of two parts was performed: Sperm rich fractions, SRF, were split, diluted with a Tris-egg yolk (TEY) extender containing 0, 5 or 10 mM GSH and stored at 4 °C for 10 days (Part 1; n = 19) or 4 days (Part 2; n = 11), respectively. For Part 1 of the study, percentage (%) of motile, viable, morphologically abnormal spermatozoa and % acrosomal deviations were assessed on days 0, 1, 2, 4 and 10 after dilution. For % sperm motility, samples from all three aliquots of each SRF (0/5/10 mM GSH) were pipetted simultaneously and analysed in a randomised order (time point of analysis, TPA). In Part 2 of the study, motility analysis was performed during 4 days storage and samples were analysed immediately after pipetting (part 2). Most investigated parameters were affected by storage time. For motility variables, there was an effect of GSH identified for circular, CM (ANOVA, Part 1: P = 0.05, Part 2: P < 0.0001) and local motility, LM (ANOVA, Part 2: P = 0.004). Furthermore, there was a trend for an interaction between time and sperm treatment for CM (Part 2: P = 0.077).In conclusion, in the present study there was not an overall positive effect of GSH addition (5/10 mM) on sperm motility in chilled dog semen samples that were characterised to be of good quality during 4- and 10-days of storage.

Impact of immediate and delayed chilling of raw milk on chemical changes in lipid fraction of pasteurized milk

BackgroundIn many developing countries, milk chilling facilities are not available on the farm where milk is produced, rather these are located at the distance of 10–12 km. After milking, it takes about 2–3 h to reach milk to the chilling facilities. The milk is then chilled and transported to the milk processing plants for thermal processing and value addition. In developing countries, shelf life of pasteurized milk is only 3 days, as compared to 7–10 days in developed countries. The factors which are responsible for the shorter shelf life of pasteurized milk should be discovered for the improvement of dairy sectors of these countries. The magnitude of chemical changes which takes place in un-chilled milk and their effect on fatty acids profile, antioxidant status and lipid oxidation is not previously studied.MethodsRaw milk samples of the same farm were either rapidly chilled to 4 °C immediately or held at room temperature (35 ± 2 °C) for 2 h followed by rapid chilling to 4 °C. Immediately and delayed chilled raw milk samples were stored at 4 °C for 72 h. Both milk samples were pasteurized at 65 °C, filled in 250 ml transparent PET bottles and stored at 4 °C for 6 days. Fatty acid profile, selenium, zinc, total antioxidant capacity, total flavonoid content and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, free fatty acids, peroxide value and anisidine value were determined at different stages of the experiment. This experiment was repeated with milk of same farm for at least five times.ResultsStoring raw milk at ambient temperature (35 ± 2 °C) significantly influenced the pH and lactose content of milk. The loss of short-chain fatty acids in delayed chilled milk was 1.19%, 3.27% and 1.60%, as compared to immediately chilled raw milk. In delayed chilled milk, loss of C18:1 and C18:2 after 3 days of storage period was 6.67% and 01.22. In delayed chilled milk after 6 days of storage, loss of C18:1 and C18:2 was 7.7% and 1.39%, respectively. In immediately chilled milk loss of C18:1 and C18:2 after 3 days of storage was 3.48% and 0.64%. In immediately chilled milk loss of C18:1 and C18:2 after 6 days of storage was 4.57% and 0.9%. Almost 41% vitamin E was lost when raw milk was stored at ambient temperature for 2 hrs. About 21% and 7% vitamin E was lost in delayed and immediately chilled milk, when samples were analyzed immediately after pasteurization. Loss of selenium and zinc contents after 2 h of ambient storage of raw milk were 0.43 and 224 μg/100 g. After 2 h of storage of milk at ambient temperature, free fatty acids increased by 0.03% (p < 0.05). After 6 days of storage, rise of free fatty acids in immediately and delayed chilled milk was 0.06% and 0.14%, respecitively. Rise of 0.13(MeqO2/kg) was recorded, when un-chilled raw milk was stored at ambient temperature for 2 h. After 3 and 6 days of storage, peroxide value of pasteurized milk (delayed chilled) was 0.88 and 1.56 (MeqO2/kg). After 3 and 6 days of storage, peroxide value of pasteurized (immediately chilled) was 0.39 and 0.42(MeqO2/kg). After 2 hrs of ambient storage, 18.41% flavonoids were lost. After 2 hrs of ambient storage of raw milk, loss of total antioxidant capacity and DPPH free radical scavenging activity was 29.31% and 44.53%. After 6 days of pasteurization, loss of total antioxidant capacity and DPPH free radical scavenging activity in delayed chilled raw milk was 72.1% and 89.57%.ConclusionsThe findings of this investigation showed that delayed chilling of raw milk leads to several undesirable chemical changes in lipid fraction of milk.

English

Biochemical changes of Atlantic salmon (Salmo salar) i¬llets during superchilled storage were evaluated. Due to the signii¬cant differences in ice crystal sizes observed, the biochemical changes were evaluated both at the top and centre parts of the superchilled samples. No signii¬cant differences were found in biochemical changes between top and centre parts of the superchilled samples. The amount of cell tissue fluid (CTF) increased significantly from day 1 to 3 in the top and centre parts of the superchilled samples. The amount of CTF was stable between day 3 and 14 but increased significantly from day 21 to 28. A significant increase in the activity of β-N-acetyl-glucosaminidase in the CTF at the top was observed between day 3 and 7, while at the centre at day 7 of storage. There was also a significant increase in β-N-acetyl-glucosaminidase both at the centre and the surface of the superchilled samples between day 21 and 28 of storage whereby the activity in these samples was on the same level as in the frozen samples. In the superchilled samples, the cathepsin B activity in CTF and homogenates were stable for the first one week of storage. There was significant increase in activity of cathepsin B in cell tissue fluid and homogenates between day 21 and 28 for both chilled and superchilled samples. These i¬ndings provides valuable information on the quality of food products for the food industry in relation to ice crystallisation/recrystallisation during superchilled storage. Key words: Partial freezing, biochemical changes, superchilled storage, salmon fish (Salmo salar).

Prevalence of Vibrio spp. in Retail Seafood in Berlin, Germany

This study was conducted to determine the prevalence of Vibrio spp. in retail seafood in Berlin, Germany. A total of 160 raw seafood samples from supermarkets and seafood shops, consisting of shrimp ( n = 80) and bivalves ( n = 80), were investigated for the presence of Vibrio spp. using the International Organization for Standardization ISO/TS 21872 method and a multiplex PCR. The overall prevalence of Vibrio spp. in retail seafood was 55% (95% CI: 47.2 to 62.8%). The prevalence of Vibrio spp. in shrimp was slightly higher than in bivalves (57.5 versus 52.5%); however, the difference was not statistically significant. Vibrio alginolyticus was the most prevalent species (35.6%), followed by Vibrio parahaemolyticus (27.5%), Vibrio cholerae (6.3%), and Vibrio vulnificus (0.6%). None of the V. parahaemolyticus ( n = 110) isolates encoded tdh/ trh genes, whereas all V. cholerae isolates ( n = 27) were lacking ctxA. Among the chilled samples ( n = 105), the prevalence of Vibrio spp. in unpacked samples was significantly higher than in packed samples ( P = 0.006). Among the packed samples ( n = 55), no significant difference in the prevalence of Vibrio spp. was observed between chilled or frozen products. The results of this study indicated a high prevalence of Vibrio spp. in retail seafood in Germany; positive samples were detected in all types of seafood investigated. The detection of tdh/ trh-negative V. parahaemolyticus isolates should not be neglected because of previous findings on pathogenic strains lacking these virulence markers. Even though thorough cooking might limit the risk of foodborne illness caused by Vibrio, potential cross-contamination during preparation or consumption of raw and undercooked seafood might represent a risk of Vibrio infections.

Effect of Super-Chilling on the Shelf Life of Chicken Nuggets

This study was conducted to assess the composition, physicochemical, microbiological and sensory quality of aerobically packaged&nbsp; chicken nuggets stored at two different superchilling temperature (-2 ±0.5ºC and -0.5±0.5ºC) and compare with storage under frozen&nbsp; (-20±1ºC) and chilling (4±1ºC) temperature for 35 days. The products stored at chilling (4±1ºC) temperature spoiled within 28 days.&nbsp; The moisture content of super-chilled samples was significantly lower than frozen sample and higher than chilled samples. However&nbsp; there was no significant variation in the fat content of the product stored at different temperatures. There was a significant increase in&nbsp; pH of chilled samples than super-chilled with progress in the storage period. The TBA and tyrosine values of the superchilled samples&nbsp; were significantly lower than chilled samples during the storage. Super-chilled nuggets showed significantly lower TPC and psychrophillic&nbsp; counts as compared to chilled nuggets. Sensory evaluation also revealed significantly high scores for super-chilled product than chilled&nbsp; nuggets indicating usefulness of super-chilling temperature for extension of shelf life.&nbsp