Drying of bioproducts

Getler J., Spray Drying of Bioproducts in Granulation Technology for Bioproducts, Boca Raton, CRC Press 1990... 

Franks, F. (1998). Freeze-drying of bioproducts putting principles into practice. European Journal of Pharmaceutics and Biophatmaceutics, 45(3), 221—229. 

A comparative study between intermittent microwave and IR drying of bioproducts was conducted by Chua and Chou (2005). The application of IR radiation in a stepwise manner, by slowly increasing the power and inserting short cooling periods between the successive power levels, resulted in less color degradation. Reductions in overall color change of 37.6% and 18.1% were obtained for potato and carrot, respectively. 

Chua, K. J., Chou, S. K., 2005. A comparative study between intermittent microwave and infrared drying of bioproducts. Int. J. Food Sci. Technd. 40(1) 23-39. 

Air-dried com stover provided by the Agricultural Utilization Research Institute was milled and then screened, and only the fraction less than 2-mm sieve was used in this research. Aspen pulping wood chips (Populus tremuloides) with a pretreatment, which were the intermediates of a biorefinery process, were provided by the Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, Minnesota. Aspen wood chips that passed through a 1 -in. sieve but not through a 0.5-inch sieve were used. Aspen wood chips were pretreated with dilute sulfuric acid to remove partial hemicellulose. 

Wheat bran, starch, powdered skim milk, casein, peat, com flour, and the like are reported to be good fillers for drying liquid bioproducts in fodder, fermentation, pharmaceutical, and similar industries [18,19]. As applied to drying of lysine, for example, the use of wheat bran as an active filler gives the following advantages ... 

W. Kaminski and C. Strumillo, Optimal control of bioproduct drying with respect to product quality. Chemical Engineering and Processing, 31, 125-129 (1992). 

I. Zbicinski and M. Piatkowski, Degradation of bioproducts in a cocurrent spray drying process, Acta Agrophysica, 11, 155-165 (2002). 

A wide variety of products can be produced by fermentation. In some cases the microorganism itself is the product, for example, in the manufacturing of active dry yeast (ADY). Well-known pharmaceutical fermentation products are insulin and penicillin G. Fermentation processes are also used to produce various commodity bioproducts like organic and amino acids, polysaccharides, lipids, chemical compounds like isoprene (Whited et al., 2010), 1,3-propanediol (Nakamura and Whited, 2003), RNA, DNA, enzymes, and other proteins. The large variety of commodity bioproducts produced by fermentation requires an equally large variety of different methods to separate and purify them. Compared to fermentation processes, where usually one unit, the fermenter vessel, is used, several different steps and unit operations are necessary to achieve purification and formulation of bioproducts. 

An example of a commodity bioproduct everybody has probably encountered is ADY. In this case, the cells are the product. The downstream processing for ADY can consist of several washing steps and concentration by centrifugation. The washing steps remove the fermentation media from the yeast cells. The yeast cream obtained by centrifugation is further concentrated using a filter-press to produce a yeast cake. Extrusion and drying of the yeast cake yields the final ADY product. 

The addition of microsalts and EDTA resulted in a biomass yield on sucrose (Yx/S) of 0.24 g/g and CMC-1/dry cell weight of 54.5, quite different from that determined for the nonsupplemented medium, 0.08 g/g and 79.2, respectively. In a way, these results suggest that the presence of oligo-elements stimulates cell growth rather than bioproduct synthesis. 

Formulation of a product depends on how the end product will be used and the ability to satisfy safety requirements. Many bioproducts are supplied in liquid form, as it is convenient to meter and use. If the compound is slated for dry products, the concentrate can either be stored for later use or applied directly for granulation. In many industries, proteins, peptides, and other bioproducts are supplied as encapsulates or granules in order to meet safety standards. 

USDA and USDOE Joint Report. 2005. A Billion-Ton Feed Stock Supply for Bioenergy and Bioproducts Industry Technical Feasibility of Annually Supplying 1 BiUion Dry Tons of Biomass. Joint Report—U.S. Department of Agriculture and U.S. Department of Energy, February 2005. 

Hatamipour, M.S. and Mowla, D., Drying behaviour of maize and green peas immersed in fluidized bed of inert energy carrier particles, Food Bioproducts Process. J., 84, 1-7, 2006. 

With respect to the product, the solid sorbent can be neutral (placebo) or active. In the first case, the sorbent is used only as a carrier for heat-sensitive and otherwise hard-to-dry materials. Liquid bioproducts such as antibiotics, enzymes, yeasts, amino acids, and the Uke, which, when conventionally dried, can lose up to 70% of their biological activity, are typical examples. Sawdust, activated carbon, and ground straw or hay are typical solid carriers. After drying, the solid sorbent is either separated from the product or left as is for further utilization, as it is in the case of fodder antibiotics [17]. Figure 21.4 shows the co- and countercurrent modes of contacting solid carriers with liquid biomaterials in a spray dryer configuration. 

K.E. Dolinov, Fundamentals of Dry Bioproducts Technology, Meditsina, Moscow, Russia (1969) (in Russian). 

Meerdink, G Van tRiet, K. Prediction of product quality during spray drying. Transactions of the IChemE Part C Food and Bioproduct Processing, 1995, 73,165-170. 

Foerst, R, Kulozik, U., Schmitt, M., Bauer, S., Santivarangkna, C. (2012). Storage stability of vacuum-dried probiotic bacterium Lactobacillus paracasei F19. Food and Bioproducts Processing, 90(2), 295-300. 

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