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Effects of cryogenic freezing by liquid nitrogen on the quality and microstructure of silver pomfret (pampus argenteus)

Effects of cryogenic freezing by liquid nitrogen on the quality and microstructure of silver pomfret (pampus argenteus)

Lu, J., Yu, H.-X., Yang, S.-B., Jiang, Q.-Q., Liu, W.-J., Dong, K.-C., Hu, Y.-Q.

中文摘要:
      银鲳鱼经液氮喷淋方法（中心温度达-40 ℃，需20 min）冻结后于-18 ℃进行冻结贮藏试验。作为对照，对大小相近的同批原料进行平板冻结（中心温度达-20 ℃，需6 h）及冰柜冻结(中心温度达-18 ℃，需20 h)处理，冻藏条件与液氮速冻样品相同。结果表明，液氮速冻、平板速冻、冰柜冻结的样品的pH值在第105天降至最低（6.42、6.35、6.11），冻藏150天后盐溶蛋白质浓度分别为6.71、3.24、1.38 mg/g，Ca2+-ATPase活性分别为1.73×10-3、0.76×10-3、0.56×10-3 μmol/(min?mg)。冻结温度愈低，K值、TVBN值增加愈小。TPA图谱分析显示，硬度、弹性和回复性均随着冻藏时间的延长呈显著降低趋势(P＜0.05)；较低的冻结温度可使各指标数值变化趋缓。微观结构观察发现，贮藏150天的液氮组样品肌纤维间隙最小、细胞完整致密，与新鲜样品最为接近；液氮深冷速冻对银鲳冻藏品质维持效果最佳。
英文摘要: Abstract:
      Silver pomfret (Pampus argenteus) was pretreated with liquid nitrogen (LN2) by spray freezing (central point temperature of -40°C in 20 min), followed by freezing storage at -18°C. For the control, samples with similar sizes in the same batch were pretreated by plate freezing (central point temperature of -20°C in 6 h) or frozen directly using a freezer (central point temperature of -18°C in 20 h). Control samples were subsequently stored at -18°C, similar to LN2 samples. The results showed that the pH values of the LN2-frozen samples, plate-frozen samples, and freezer-frozen samples reached minima at 6.42, 6.35, and 6.11, respectively, on the 105th day; the salt-soluble protein contents were 6.71, 3.24, and 1.38 mg/g, respectively, and the Ca2+-ATPase activities were 1.73 × 10-3, 0.76 × 10-3, and 0.56 × 10-3 μmol/(min?mg), respectively. The increases in K values and total volatile base nitrogen were limited with lower prefreezing temperatures. Texture profile analysis (TPA) showed that the hardness, springiness, and resilience of frozen fish meat decreased significantly (P < 0.05) with prolonged storage time. In contrast, a low prefreezing temperature may result in slower changes in these indices. Microstructure observations showed that LN2-frozen samples appeared the most similar to the fresh material, with a narrow gap between the myofibrils and excellent cell integration after storage for 150 days. The results indicated that the LN2 spray method was the best of the three tested methods for maintenance of the quality of silver pomfret.

words: liquid nitrogen cryogenic freezing  silver pomfret (Pampus argenteus)  K value  total volatile base nitrogen value  Ca2+-ATPase activity  texture profile analysis  microstructure

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Pharmaceutical spray freeze drying

Pharmaceutical spray freeze drying

Stefan Wanning, Richard Süverkrüp, Alf Lamprecht

Abstract

Pharmaceutical spray-freeze drying (SFD) includes a heterogeneous set of technologies with primary applications in apparent solubility enhancement, pulmonary drug delivery, intradermal ballistic administration and delivery of vaccines to the nasal mucosa. The methods comprise of three steps: droplet generation, freezing and sublimation drying, which can be matched to the requirements given by the dosage form and route of administration. The objectives, various methods and physicochemical and pharmacological outcomes have been reviewed with a scope including related fields of science and technology.

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Preparation of transparent neodymium-doped yttrium aluminate garnet (Nd:YAG) ceramics with the use of freeze granulation

Preparation of transparent neodymium-doped yttrium aluminate garnet (Nd:YAG) ceramics with the use of freeze granulation

Anna Wajler, Helena Węglarz, Agata Sidorowicz, Łukasz Zych, Magdalena Nakielska, Katarzyna Jach, Henryk Tomaszewski

Abstract

This paper presents the results of the application of freeze granulation to the production of transparent neodymium-doped yttrium–aluminum garnet ceramics. Aqueous suspensions of aluminium oxide, yttrium oxide and neodymium oxide powders were prepared based on nanometric or submicronic powders which were either commercially available or prepared by precipitation. The relations between the composition of suspension, the properties of granulate and the final properties of ceramics (microstructure, optical transmission and emission spectra) were studied.

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Granulation techniques and technologies: recent progresses

Granulation techniques and technologies: recent progresses

Srinivasan Shanmugam

Pharm. R&D Institute, Hanmi Pharm. Co., Ltd., Hwasung, Gyeonggi, Korea

Abstract

Granulation, the process of particle enlargement by agglomeration technique, is one of the most significant unit operations in the production of pharmaceutical dosage forms, mostly tablets and capsules. Granulation process transforms fine powders into free-flowing, dustfree granules that are easy to compress. Nevertheless, granulation poses numerous challenges due to high quality requirement of the formed granules in terms of content uniformity and physicochemical properties such as granule size, bulk density, porosity, hardness, moisture, compressibility, etc. together with physical and chemical stability of the drug. Granulation process can be divided into two types: wet granulation that utilize a liquid in the process and dry granulation that requires no liquid. The type of process selection requires thorough knowledge of physicochemical properties of the drug, excipients, required flow and release properties, to name a few. Among currently available technologies, spray drying, roller compaction, high shear mixing, and fluid bed granulation are worth of note. Like any other scientific field, pharmaceutical granulation technology also continues to change, and arrival of novel and innovative technologies are inevitable. This review focuses on the recent progress in the granulation techniques and technologies such as pneumatic dry granulation, reverse wet granulation, steam granulation, moisture-activated dry granulation, thermal adhesion granulation, freeze granulation, and foamed binder or foam granulation. This review gives an overview of these with a short description about each development along with its significance and limitations.

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Thermal properties of alumina–MWCNTs composites

Thermal properties of alumina–MWCNTs composites

Alumina–multi-wall carbon nanotubes composites were prepared using a new approach. This process comprises functionalization MWCNTs by acid treatment, stabilization of alumina–MWCNT dispersion with subsequent freezing was used, which resulted in formation of granulated powder with homogeneous distribution of MWCNTs. The ceramic composites were prepared by hot pressing and rapid hot pressing at 1550 °C using these granulated powders. Relative densities, microstructural analysis, Raman spectroscopy, heat capacity as well as thermal diffusivity measurements of composite prepared by hot press and rapid hot press has been studied. Our results show that sintering alumina–MWCNT granulated powder by rapid hot press is effective way how to reach nearly fully dense composite up to 12.5 vol.% of MWCNTs. Relative density of alumina–MWCNT composite with 10 vol.% of MWCNTs in case of composite prepared by rapid hot press was 97.3% of theoretical density whereas in case of composite with same content of MWCNTs prepared by hot press relative density was 79.5%. Thermal diffusivity of composite sintered by rapid hot press and hot press decrease with increasing content of MWCNTs and increasing measuring temperature up to 400 °C. Thermal diffusivity of composites prepared by rapid hot press, which have higher density than composite prepared by hot press, is slightly higher. Thermal conductivity of composites prepared by rapid hot press decrease with increasing content of MWCNTs from 27.8 to 16.7 W/m K and in case of composite prepared by hot press from 24.6 to 7.8 W/m K. This is probably due to the phonon scattering of incorporated MWCNTs in alumina matrix and their intrinsic defects.

Keywords

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Freeze Granulation of vanillin flavour

Effect of whey protein isolate and β-cyclodextrin wall systems on stability of microencapsulated vanillin by spray–freeze drying method

Vanillin flavour is highly volatile in nature and due to that application in food incorporation is limited; hence microencapsulation of vanillin is an ideal technique to increase its stability and functionality. In this study, vanillin was microencapsulated for the first time by non-thermal spray–freeze-drying (SFD) technique and its stability was compared with other conventional techniques such as spray drying (SD) and freeze-drying (FD). Different wall materials like β-cyclodextrin (β-cyd), whey protein isolate (WPI) and combinations of these wall materials (β-cyd + WPI) were used to encapsulate vanillin. SFD microencapsulated vanillin with WPI showed spherical shape with numerous fine pores on the surface, which in turn exhibited good rehydration ability. On the other hand, SD powder depicted spherical shape without pores and FD encapsulated powder yielded larger particle sizes with flaky structure. FTIR analysis confirmed that there was no interaction between vanillin and wall materials. Moreover, spray–freeze-dried vanillin + WPI sample exhibited better thermal stability than spray dried and freeze-dried microencapsulated samples.

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Spray freeze drying for dry powder inhalation of nanoparticles

Spray freeze drying for dry powder inhalation of nanoparticles

Formulating nanoparticles for delivery to the deep lung is complex and many techniques fail in terms of nanoparticle stability. Spray freeze drying (SFD) is suggested here for the production of inhalable nanocomposite microcarriers (NCM). Different nanostructures were prepared and characterized including polymeric and lipid nanoparticles. Nanoparticle suspensions were co-sprayed with a suitable cryoprotectant into a cooled, stainless steel spray tower, followed by freeze drying to form a dry powder while equivalent compositions were spray dried (SD) as controls. SFD-NCM possess larger specific surface areas (67–77 m2/g) and lower densities (0.02 g/cm3) than their corresponding SD-NCM. With the exception of NCM of lipid based nanocarriers, SFD produced NCM with a mass median aerodynamic diameter (MMAD) of 3.0 ± 0.5 μm and fine particle fraction (FPF ⩽ 5.2 μm) of 45 ± 1.6% with aerodynamic performances similar to SD-NCM. However, SFD was superior to SD in terms of maintaining the particle size of all the investigated polymeric and lipid nanocarriers following reconstitution (Sf/Si ratio for SFD ≈ 1 versus >1.5 for SD). The SFD into cooled air proved to be an efficient technique to prepare NCM for pulmonary delivery while maintaining the stability of the nanoparticles.

Keywords

  • Spray freeze drying;
  • Spray drying;
  • Pulmonary;
  • Nanoparticles;
  • Dry powder;
  • Inhalation;
  • Nanocomposite microcarriers

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Spray Freeze Granulation of Nano Powders for Die Pressing

Spray Freeze Granulation of Nano Powders for Die Pressing

Jon Binner, Ketharam Annapoorani, Bala Vaidhyanathan

The processing of nanocrystalline yttria doped zirconia powder via dry forming routes has been investigated via the granulation of the powder using spray freeze drying (SFD). Free-flowing and crushable powders suitable for either die or isosatic pressing have been achieved via the combination of SFD with additions of up to 2 vol% of Freon 11; the latter reducing the strength of the granules whilst not affecting the powder flowability into the die. The approach has allowed relic-free green bodies of up to 55% of theoretical density to be produced using pressures as low as 250 MPa.

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