There are two major research areas in food Freezing processes. The first direction includes estimation of Freezing and chilling Time and the other covers the studies entailing dynamics and design of chillers and freezers. In this paper the Freezing and heat transfer dynamics of fisheries products along the first above mentioned field have been investigated. The simulation results can then be used elaborately for design attitudes of industrial freezers. Through the article the Freezing process is firstly modeled or fomulated and afterwards, the models have been solved numerically using finite difference methods. The results can be applied to calculate the Freezing Time and weight loss of product under various operational conditions such as different temperatures and cold air speeds. Also, the effect of fish (food) size, type and initial temperature has been studied. Four different models and solution methods have been used and it is demonstrated that the model of simultaneous heat and mass transfer gives the most accurate results.

Liens tolerate environmental stresses utilizing is one of the applicable technologies in sustainable agriculture. Since occurrence of a suitable winter for studing and selection of cold/frost resistance on breeding materials is one year out of ten, therefore laboratory methods complementing field data provide a reasonable solution for this propose. This research was conducted in Khorasan Agri. Res. Center. Mashhad. Using RCBD in three replications during 1380-81. Treatments consisted of twenty promising genotypes of uniform regional yield trail (cold area). Genotypes suits low temperature regions will be introduced based on generated results from this investigation. Using crown Freezing method, experimental genotypes were treated with -20. C temperature under controlled conditions. Survival percentage was computed. Results indicated that genotypes No.9 (C-78-9) and No.7 (C-78-7) had highest (98.33%) and lowest (66.67%) survival percentage respectively. The minimum Crown Moisture Content was detected in line No. 9 (C-78-9) and there was no significant difference for the same trait between genotype No.7(C-78-7) and other superior genotypes. A high negative correlation (r=-0.701) was observed between survival percentage after exposing to frost and crown moisture content. Ear primordia development stage was one of the characters which had also a significant correlation with survival percentage (r=-0.619). Significant correlation between survival percentage and days to heading (r=-0.207) and days to physiological maturity (r =-0.028) was not observed. Correlation between survival percentage and collected cold damage data from experimental fields over five low temperature regional stations was highly significant (r=0.416), therefore it may be concluded that Crown Freezing Method and subsequent computing of survival percentage is a reliable method for estimating wheat frost/cold tolerance in natural conditions.

Introduction: The main method of separating platelet microparticles (PMP) is based on the centrifugation speed and Time. Due to the high cost of determining the number of PMP via micro-particles (micro bead) and also the necessity of using an expensive device such as a flow cytometer, it seems that Bradford method would be rather an inexpensive, fast and efficient way to determine the concentration of PMP. Therefore, in this study the effect of different factors, such as speed and Time of centrifugation and Time of Freezing on the concentration of PMP in the platelet concentrates bags was studied.Materials and Methods: We studied two different speeds of centrifugation for separating PRP. In the first protocol for preparation of PRP, the platelet bags were centrifuged at 1500g for 15min and in the second protocol; they were centrifuged at 5000g for the same duration. To evaluate the effect of Time, microparticles were separated in 16000g for 20 and 2 min. To determine the concentration of PMP, Bradford method was used. To evaluation the effect of Freezing, the PRP was prepared at 300g for 20 min, and then it was freezed in -80oc for five days. Flow cytometery analysis was performed for microparticles identification.Results: PMP concentrates with the 1500g centrifugation speed showed higher concentration (P<0.05). There was not any significant difference in concentrations of PMPs in relation to the Time of centrifugation (2 and 20 min) (P<0.05). Freezing the platelet bags led to higher PMP concentration in compare to the first day of experiment. Flow cytometry analysis showed that microparticles had platelet marker CD41, which represented their origin.Conclusion: The result of this study showed that the reduction of centrifugation speed could produce higher levels of the microparticles. In addition, the Time of separation in the final stage had no significant effect on PMP isolation. Freezing could lead to higher PMP concentration.

Maintaining the nutritional quality and preserving pomegranate seeds is a major challenge due to the fast degradation of the texture, color and overall quality of pomegranate seeds. In order to investigate the Freezing of coated pomegranate seeds with chitosan and determine its quality during Freezing storage, an experiment was conducted, in a factorial arrangement in a completely randomized design with three replications. Factors were: chitosan at three levels (0, 1 and 2%), Freezing temperature at two levels (-14 °-24 ° C) and Time at 5 different storage Times (14 days, 30 days, 60 days, 90 days, and 120 days). The highest tissue firmness was observed for 14 days of storage under both chitosan concentrations. Interaction of different levels of chitosan coating and Time had an increasing effect on the color component changes, so that the most color changes in the brightness (L*), redness (a*), and yellowness (b*) was related to the use of chitosan coating 2%, were maintained at 60 days. The highest total soluble solids were related to 1% chitosan under 4 months of storage at-14° C. Maximum total acidity (1. 36 mg / L) was also attributed to coated pomegranate seeds during 120 days of storage under both Freezing temperatures of-14° C and-24° C. The results of mean compares showed that the total phenol stability under Freezing temperature was higher at-14° C and after 120 days of storage, more phenol content was observed in the seeds in-24 C. The overall results indicated a positive effect of chitosan on maintaining the quality of pomegranate seeds during Freezing, and the Freezing temperature of-24 ° C with decreasing color changes during storage, played an important role in reducing metabolic activity and reducing anthocyanin degradation and was effective in maintaining fruit quality.

Aim: The purpose of this study was to consider the effect of mild oxidative stress period on the frozen-thawed bull semen performance.Material and Methods: In this study, 120 minutes was considered for equilibration of sperm before Freezing. One mm of Nitric Oxide (NO) at the 0, 45, 90 and 120 cooling period was added to the diluant before cryopreservation. Sperm motion parameters, plasma membrane integrity, acrosome integrity, viability, apoptosis and mitochondria activity were assessed.Results: Induction of oxidative stress with nitric oxide in the T0 and T45 groups led to significant improvement of total (88.4±2.8, 84.7±2.7) and progressive motility (50.4±2.5, 49.5±2.5) when compared to other groups. Percentage of plasma membrane integrity and viability were not different in T0 (74.4±2.9 and 85.6±2.9) and T45 (75.6±2.9 and 84.6±2.3) groups, where as it was significantly higher when compared with T90 (63.6±2.9 and 69.6±2.3) and T120 (61.5±2.9 and 54±2.3). Moreover, the highest significant percentage of spermatozoa with active mitochondria was observed in the T0 (82.5±3.1) when compared with T45 (65.7±3.1), T90 (42±3.1) and T120 (43±3.1). Acrosome integrity and linearity of sperm were not affected by the oxidative stress treatment Time.Conclusion: It seems that applying oxidative stress using 1 mM NO would improve post-thawed bull sperm quality at the T0 and T45 Time of cooling.

Foods are generally subjected to thermal treatments during processing operations, which affect the rheological properties of hydrocolloid solutions. In this study, cress seed gum and xanthan gum were prepared at 1% (w/w) and subjected to heating (60oC-30min, 80oC-23min, 100oC-18min and 121oC-15min) and Freezing treatments (-18oC-24h and -30oC-15h). Then the rheological properties of hydrocolloid solutions were determined at 25oC by a rotational viscometer (Bohlin Model). When the hydrocolloid samples were heated, an irreversible increase in viscosity of cress seed gum solutions was observed, whereas xanthan gum would not have the ability to stand against heat treatment. In Freezing process, conversion of water to ice leads to an increment in molecular association and improved rheological characteristics of cress seed gum and xanthan gum.

It should now be beyond doubt that blastocyst culture results in better pregnancy rate (PR). This calls for fewer embryos to be transferred, and indeed blastocyst culture is of most value when the intention is to put back one embryo at a Time.The PR with one top-grade blastocyst is 45-65% in different studies. If two top-grade blastocysts are transferred, the PR usually does not differ, but the rate of multiples increases manyfold. Given a good Freezing programme, the cumulative PR after one fresh and one frozen single blastocyst transfer exceeds that of a fresh two-blastocyst transfer.Culture can be done open, or in drops under oil. The use of a low-oxygen (”three-gas”) incubator is beneficial.ET shall be performed on day 5. PR decreases if fresh ET is done on day 6, but embryos frozen on day 5 or day 6 perform equally when transferred in a freeze-thaw cycle.Preferrably, this should be a spontaneous or a FSH stimulated cycle. Oestrogen / progesteron cycles may result in a higher rate of miscarriages.Only top-grade or next to top-grade blastocysts should be frozen to ensure good results. The fact that there are fewer day 5 embryos to be frozen than after 2-3 days culture is an advantage rather than the opposite, as the PR per embryo is higher.Puncturing of the expanded blastocyst is crucial and can be done just as well with a needle as by laser. Most studies have shown that vitrification is superior to slowFreezing, but these studies often have surprisingly poor results for slow-Freezing with low surviving rates and low PR. At our unit, 76% of thawed blastocysts survive and are transferred with a PR after transfer of a single blastocyst of 56%, which is the same as the comparable fresh transfer.Where three or more embryos are transferred, there is no advantage of blastocyst culture. Indeed, it only results in even more multiple pregnancies.