SCREENING FOR A SUITABLE CRYOPRESERVATION PROTOCOL FOR Polypodium vulgare

The objective of this work was to evaluate cryoprotectants on the physiological quality of Adenium obesum seeds preserved in liquid nitrogen. The following treatments were used: T1, control, without cryoprotectant and without immersion in liquid nitrogen; T2, with immersion in liquid nitrogen and without cryoprotectant; T3, with 0. 4 mol L-1 sucrose; T4, with 0.8 mol L-1 sucrose; T5, with 1.0 mol L-1 glycerol; T6, with 2.0 mol L-1 glycerol with PVS1; T7, with PVS1; T8, with PVS2; T9, with PVS2 + phloroglucinol (modified PVS2); and T10, with PVS3. Adenium obesum seeds show tolerance to immersion and storage in liquid nitrogen and do not need cryoprotectants to maintain their physiological quality when stored in a water content of 7.5%.

Recent advances in the cryopreservation of shoot-derived germplasm of economically important fruit trees of Actinidia, Diospyros, Malus, Olea, Prunus, Pyrus and Vitis

In the present study, we compared the structure of ice formation in cryobiologically relevant solutions immersed in liquid nitrogen with solutions that were laser heated prior to immersion in a liquid-nitrogen bath. The results suggest that there is a distinct and observable difference in the type of ice formed. Furthermore, we also present data that suggest pulsed laser heating prior to immersion in liquid nitrogen enhances post-thaw survival of cells in suspension. The laser used in our experimental approach was a Q-switched Quanta-Ray DCR-3 laser (Nd:yttrium aluminum garnet laser) operating in the second harmonic at 532nm. The laser irradiance consisted of pulses with a pulse width of 5–7ns and a pulse energy stability of 3%. The pulse energy at a pulse repetition rate of 1Hz was about 360mJ and the peak power delivered was about 60MW. The samples were held in a copper- (sheet thickness of 0.5mm) molded rectangular box of 5mm thick, 25mm wide, and 15mm long. Preliminary experiments were carried out using adipose-tissue-derived adult stem cells. The pre- and postfreeze∕thaw viability of ADAS cells was assessed using membrane-excluded fluorescent dyes. ADAS cells enclosed in a copper box, laser irradiated, and exposed to liquid nitrogen had a viability of 69%±5%. Similarly, when the cells were exposed directly to liquid nitrogen (note that as before the cell suspension was enclosed and sealed in the copper box), the viability reduced significantly to 9%±10%. These results are very encouraging and demonstrate the feasibility of using lasers and liquid nitrogen to cryopreserve cells in suspension.

Quality and microstructure of tilapia fillets (Oreochromis niloticus) subjected to different freezing methods

Thin unmounted cortical tissue sections from winter twigs of the mulberry tree were held with a thin forceps and rapidly immersed in liquid nitrogen from room temperatures without prefreezing. They were rewarmed; rapidly in water at 10 degrees to 40 degrees , or slowly, in air at room temperatures. In those sections rapidly rewarmed, all survived. None survived in those sections rewarmed slowly in air.Tissue sections mounted between coverglasses with water were extracellulary prefrozen at the temperatures low enough to dehydrate almost all of the freezable water in cells. These sufficiently prefrozen cells could survive immersion in liquid nitrogen, and the survival value was very little affected by the rates of cooling to and rewarming from super-low temperatures. With insufficient prefreezing at higher temperatures, however, the rewarming process seriously influenced the survival value of cells frozen at super-low temperatures. Slow rewarming in air destroyed all of the cells, while rapid rewarming in water at 30 degrees did not affect them. An abrupt decrease in the survival value in insufficiently prefrozen cells during rewarming was also observed at temperatures above approximately -50 degrees following immersion in liquid nitrogen. Very little decrease in the survival value was observed in any of the cells that had been sufficiently prefrozen.These results indicate that cells which are insufficiently prefrozen may contain freezable water which nucleates during rapid cooling in liquid nitrogen and then grows during the subsequent slow rewarming into ice masses which destroy the viability of the cells. Such fatal intracellular freezing rarely occurs in sufficiently prefrozen cells, irrespective of the rate of cooling to or rewarming from super-low temperatures.

Christmas bush (Ceratopetalum gummiferum Sm) is a shrubby tree species of the east coast of New South Wales in Australia. It is much prized as a cut flower crop because of its bright, pinky red floral calyces. New varieties are being developed, the storage of which is an important issue. In this study, it was shown that shoot tips sampled from in vitro plantlets withstood cryopreservation using the encapsulation–dehydration technique. The protocol leading to optimal regrowth was the following: excised shoot tips were pretreated for 1 d in the dark on hormone-free Murashige and Skoog (MS) medium with 0.3 M sucrose, then encapsulated in 3% calcium alginate and precultured in liquid MS medium with 0.5 M sucrose for 3 d. Precultured beads were dehydrated for 6 h in the air current of the laminar flow cabinet to 24.3% moisture content (fresh weight basis) before rapid immersion in liquid nitrogen. Under these conditions, regrowth of shoot tips after cryopreservation reached 61.4%. Regrowth of cryopres...

This paper studies the effect of staged cooling of compounded cylinders in avoiding cracking due to the presence of large interference stresses and low fracture toughness in the presence of cryogenic temperatures. This study is motivated by the assembly procedure of the fulcrum (a compounded trunnion-hub assembly) of bascule bridges, where the fulcrum is shrunk by immersion in liquid nitrogen so that it can then be fitted into the girder of the bridge. In a few cases, the fulcrum developed cracks during the immersion in liquid nitrogen. To study the effect of staged cooling to avoid such cracking, a finite difference model was developed of a long compounded cylinder with axisymmetric response with temperature-dependent properties. The study showed that the resistance to failure was increased by as much as 50 per cent when the compounded cylinder is cooled first in a refrigerated air chamber and followed by immersion in liquid nitrogen.

Reliable encapsulation-based cryopreservation protocol for safe storage and recovery of grapevine embryogenic cell cultures

Cryogenic chilling of pork carcasses: Effects on muscle quality, bacterial populations and palatability

Freezing preservation is one of the most effective methods used to maintain the flavour and nutritional value of fruit. This research studied the effects of different freezing conditions, -20 °C, -40 °C, -80 °C, and immersion in liquid nitrogen, on quality changes of freeze-thawed blueberries. The water distribution estimates of blueberries were measured based on low-field nuclear magnetic resonance (LF-NMR) analysis. The pectin content, drip loss, and fruit texture were also detected to evaluate quality changes in samples. The freezing curves of blueberry showed super-cooling points at -20 °C and-40 °C, whereas super-cooling points were not observed at -80 °C or in liquid nitrogen. After freeze-thaw treatment, the relaxation time of the cell wall water (T21 ), cytoplasm water and extracellular space (T22 ), and vacuole water (T23 ) were significantly shortened compared to fresh samples, which suggested a lower liquidity. Although the freezing speed for samples immersed in liquid nitrogen was faster than other treatments, samples treated at -80 °C showed better quality regarding vacuole water holding, drip loss, and original pectin content retention. This study contributed to understanding how freezing temperature affects the qualities of blueberries. The super-fast freezing rate might injure fruit, and an appropriate freezing rate could better preserve blueberries. © 2018 Society of Chemical Industry.

Improved Temperature Stability in Gas-Phase Nitrogen Refrigerators: Use of a Copper Heat Shunt

Cryopreservation is a frequently used method of long-term storage of potato meristems and pollen in liquid nitrogen (LN) in temperature of -196°C. This technique allows for theoretically unlimited storage of potato material. The most popular method of potato shoot tips preservation is cryopreservation by the solidification of liquids without crystallization (vitrification).The best method of pollen conservation is its direct immersion in LN. The successful regeneration after vitrification is genotype-dependent, which require optimization of protocol.

Influences of air blast freezing (AF method), cryogenic freezing (CF method), and freezing by direct immersion in liquid nitrogen (LN method) and thawing by refrigerator (RG method) and microwave (MW method) on qualities of durian puree (cv. Monthong) were investigated. After the freezing process and frozen storage, all frozen samples greatly tended to change physico-chemical parameters; drip loss (7.94–97.98%) and a* (17.45–69.75%), flavor properties; aldehydes (1.35–136.99%) and alcohols (4.86–107.22%), and sensory scores; overall flavor (4.76–26.89%) and overall liking (4.48–22.19%) from zero months of storage. However, the lowest change in almost all parameters resulted from using the CF method. Furthermore, at zero months of frozen storage, the MW method changed some physico-chemical properties less than the RG method, but there were no differences in any parameters between both methods after 6 months. Moreover, during frozen storage the MW method developed a new volatile compound, namely 3-methylbutanal, which presented an off-flavor. Practical applications Determining the shelf life of fresh fruit and processed fruit has been much more important in research and development for providing the best quality for consumers as well as international fruit trade. However, some reports have studied preserving durian, no studies are available on the influence of freezing and thawing methods on physico-chemical, flavor, and sensory changes in durian puree (cv. Monthong). Therefore, in the current study, freezing methods (air blast freezing, cryogenic freezing, and freezing by direct immersion in liquid nitrogen) and thawing methods (refrigerator and microwave) were used to study their effects on the quality changes of durian puree after the freezing process and frozen storage. The results could provide best practice and guidance for the fruit industry.

The survival of dormant, vegetative apple buds frozen to −30 °C or −40 °C for 5 min or 24 h prior to immersion in liquid nitrogen was investigated for 15 apple cultivars. Although survival after immersion in liquid nitrogen was optimum for the majority of cultivars when prefrozen to −30 °C for 24 h, some cultivars had low survival regardless of the prefreezing treatment. For these cultivars, survival was improved if the tissue was dehydrated prior to prefreezing.Key words: Malus domestica Borkh., apple freezing, moisture content, cold hardiness

We observed an interesting time-dependent recovery of critical current in an unsymmetrical Ag-sheathed Bi(2223) multicore tape. The cores were arranged unsymmetrically relative to the neutral axis of the tape. The phenomenon was observable after the tape had been bent on the side containing more Bi(2223) cores to a certain diameter in a distinct interval and then straightened at room temperature and immersed in liquid nitrogen. We explain the observed behaviour as follows: (i) on bending, the Bi(2223) grains are wedged together and then, on straightening, they are drawn away and (ii) after immersion in liquid nitrogen the grains slowly glide together again under the compressive action of the Ag sheath.