Optimisation of spray drying by response surface methodology for the production of Sinorhizobium meliloti powder formulation by using starch industry wastewater

• Published in: Biosystems engineering 2013-03, Vol.114 (3), p.334-343
• Main Authors: Rouissi, Tarek, Mahmoudi, Amin, Tyagi, Rajeshwar D., Brar, Satinder K., Prèvost, Danielle, Surampalli, Rao Y.
• Format: Article
• Language: English
• Subjects: additives; Agricultural machinery and engineering; Agronomy. Soil science and plant productions; air drying; alfalfa; Biological and medical sciences; cell viability; cheese whey; cold storage; cultured cells; drying temperature; food processing wastes; Fundamental and applied biological sciences. Psychology; Generalities. Biometrics, experimentation. Remote sensing; industry; nodulation; response surface methodology; shoots; Sinorhizobium meliloti; sorbitol; spray drying; starch; sucrose; wastewater; whey powder
• ISSN: 1537-5110; 1537-5129
• DOI: 10.1016/j.biosystemseng.2013.01.003

A spray-drying process was optimised by response surface methodology for the development of a powder formulation of Sinorhizobium meliloti (produced in starch industry wastewater). The process parameters comprised drying temperature, air drying rate, spray pressure and feed sample rate. Cheese whey powder, sorbitol and sucrose were added at 10, 1 and 1%w/v, respectively before drying. Responses studied comprised cell viability, moisture and outlet temperature. Under the optimal conditions (maximum desirability=0.81), the formulation showed cell viability of 6.8×109CFUg−1, moisture of 11.4% and outlet temperature of 42°C. During 4 months of refrigerated storage, viability was maintained at >109CFUg−1. Analysis of inoculated alfalfa plants showed that powder formulation induced similar shoot yield on dry basis (144.6mg) (p=0.23) and nodulation index (15.2) (p=0.18) compared to fresh cells cultured in standard media (shoot yield and nodulation index were 131 and 14mg, respectively). Micrographs showed that cells were embedded in the mixture of additives (whey–sucrose–sorbitol) which acted as a matrix. ► Spray-drying process for production of Sinorhizobium meliloti powder formulation optimised. ► Optimised powder formulation using RSM and study its stability for 4 months. ► The efficiency of the formulation when applied to seeds tested. ► Under optimal conditions of spray drying, a new powder formulation was developed. ► Tests showed that additives used guaranteed cells activity during nodulation.