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To crystallize ammonium sulfate (AS) of a coarse fraction of 1 to 3 mm size, a semibatch evaporative crystallization mode was applied. The crystal size was controlled by supersaturation. The induction time and supersaturation were analyzed in seeded and unseeded semibatch crystallizations. The interfacial tension was obtained by nucleation experiments. Experimental results indicated that supersaturation was strongly dependent on the metastability of the system and had a strong influence on the crystal growth. This result will contribute to a better understanding of the control of the particle size of AS by supersaturation. Coarse AS crystals can be obtained at supersaturation of 0.02−0.06 in seeded semibatch evaporation crystallization.

Single cell protein (SCP) is used as a protein supplement in animal feed and protein rich foods for humans. In this study, extracts of pineapple waste were used as substrate for SCP production using Saccharomyces cerevisiae sp. (Baker or brewing yeast). The study also focused on the effect of the pineapple substrate concentration on the yield of SCP. Pineapple waste were collected from food processing companies in Kumasi and processed into pineapple juice extracts. The residual soluble sugars in the extract were measured and the concentration adjusted (40-100% v/v) for various submerged yeast fermentations to produce the SCPs. Initially, the yeast cells were cultured on Yeast Potato Dextrose Agar (YPDA) and then transferred into a Nutrient Broth to generate the activated yeast inoculum for the final fermentation. Pineapple extracts in 2.50 3 10 24 m 3 conical flasks at various concentrations were each inoculated with 1 mL inoculum. The set-ups were incubated at 298 K and the yeast cells or colonies counted at 24 hr interval for 5 days. Biochemical analysis of the substrate revealed the following composition: pH of 5.5 and 4.7% (m/v) total soluble sugars. Maximum yield and doubling time/hr of SCPs (3.01 kg/m 3 , 1,108 hr) was observed for the 60% (v/v) pineapple substrate concentration. The 100% (v/v) substrate concentration pro-duced the least SCP yield of 2.5 3 10 22 kg/m 3 . It is concluded from this study that pineapple waste generated in the food processing industry serves as good substrates for SCP production with high-potential economic value. Practical applicationsSingle cell proteins are utilized mainly as food supplement for human beings and animals. Several other applications of single cell proteins are available. It is used as a health food to control obesity, and provide instant energy to especially sports men. It is also used in therapeutic and natural medicines to: reduce body weight, cholesterol, stress, lower blood sugar in diabetic patients, promote healthy eyes and skin, and increase lactation. It is further used in the technical field for paper and leather processing, and as foam stabilizer. K E Y W O R D S growth rate, pineapple waste, Saccharomyces cerevisiae, single cell proteins (SCP)

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