Storage and reconstitution

Although the shelf-life of a labile bioproduct will be appreciably extended by freeze-drying, stored material will not be immune to thermal decay and it may be necessary to store the freeze-dried product within a refrigerator to ensure maximum stability. For use, the dried product is reconstituted with water or an alternative medium and the hazards associated with both product storage and reconstitution will be addressed in section 10.4. 

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Proteins must be stable during processing, storage, and reconstitution (if lyo-philized). Although liquid formulation is preferred for protein biopharmaceuticals, it may not always be the most stable presentation. The biopharmaceutical protein may need to be lyophilized to maintain stability. Lyophilization involves the removal of water from a frozen substance by sublimation and water vaporization under vacuum.17 But in some cases, this process may itself cause protein instability. 

The first commercially developed emulsion, Fluosol-DA (Green Cross Corp. Osaka, Japan), was stabilized using a mixture of 6 and F-tripropylamine (FTPA, 7, 30% of total PFC) (Table 2). However, the product s stability was still poor Fluosol had to be frozen for shipment and storage, and reconstituted prior to use. Fluosol utilized a surfactant system that included poloxamer-188 (Pluronic F-68) with smaller amounts of EYP and potassium oleate. The poloxamer provided steric stabilization, and potassium oleate introduced negative charges on the droplets, likely to oppose flocculation. 

For a very long time, freeze-drying has been essentially concerned with the preservation of unstable biochemicals and, more particularly, of injectables. The very first issue was, then, to secure their sterility and safeguard then-potency during processing, storage, and reconstitution. At the outset most products were freeze-dried as such, either as a natural substance, such are blood plasma, biosynthetic isolates, or antibiotics, or, else, for vaccines. 

St ore antibodies in small, preferably sterile, aliquots at a minimum of 20°C. Repeated freezing and thawing should be avoided. For long-term storage, aliquots may be freeze-dried and reconstituted when needed (see Note 6). 

Figure 3. Changes in ascorbic acid content of freshly squeezed orange juice and reconstituted orange juice concentrate during storage in refrigerator (62)...

Fluid-applied membranes require similar storage, and unless the manufacturer advises to the contrary, the component materials may be stored in the same manner and under the same conditions as the sheet materials. However, all latex emulsions, and some few other materials, can be damaged by freezing, and it is unlikely that such damaged material can be reconstituted at the site. In any case, if freezing occurs, the manufacturer should be notified on the chance that he may want the material returned rather than discarded. 

The storage and mobilization of surplus iron in eukaryotes and some prokaryotes are regulated by the iron storage protein, ferritin. Ferritin isolated from horse spleen consists of a hollow spherical shell of 24 symmetrically related protein subunits (—18 kDa per subunit) surrounding a core of inorganic hydrated iron(III) oxide 45). Phosphate may be associated with the surface of the iron oxide core in horse ferritin, but does not appear to be a critical factor for core formation in reconstituted ferritins (46). The diameter of the cavity set by the protein shell is of the order of 70-80 A, resulting in an upper limit of 4500 iron atoms (-30% wt/wt Fe) that can be stored within the molecule. 

Wang, X.Y. et al., Vitamin C stabihty during preparation and storage of potato flakes and reconstituted mashed potatoes, J. Food Sci., 57, 1136, 1992. 

Table III gives the protein content and percent haze readings for the single-strength apple juice and reconstituted apple juice concentrate samples. All of the samples showed high clarity as evidenced by the low haze readings, none having a propensity towards haze or sediment formation. A decrease in total soluble proteins was observed with increased storage time of apple fruit. Fining resulted in ca. 25-50% reduction in total soluble protein.

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