Production Of Aroma Compounds

One of the significant applications of SSF in food applications involves production of food aroma compounds. There are two main advantages of SSF as an alternative technology for the production of aroma compounds: (1) release of the products from the microbial membranes is facilitated by the higher concentration in liquid phase, and (2) sometimes the solid substrates or byproducts can be used directly in SSF without any pretreatment of the starting substrates.

SSF has been successfully employed for the production of food aroma compounds using fungal and yeast cultures, such as Neurospora sp., Zygosaccharomyces rouxii, Aspergillus sp., and Trichoderma viridae (142), using pregelatinized rice, miso, cellulose fibres, and agar. Rhizopus oryzae cultivation of tropical agro-industrial residues results in the production of volatile compounds such as acetaldehyde and 3-methyl butanol (143). Neurospora sp. and T. viride produce a fruity odour and coconut aroma in SSF with pregelatinized rice and agar medium, respectively (142). Methyl ketones are produced on a commercial scale from coconut oil using A. niger, and the yields are as high as about 40% (1,141,143).

Ceratocystis sp. produces a large range of fruity or flower-like aromas (peach, pineapple, banana, citrus, and rose), depending on the strain and cultivation conditions (144). Among these, C. fimbriata has been extensively studied for the production of aroma compounds in SSF. Wheat bran, cassava bagasse, coffee husk, and sugarcane bagasse were used as the substrate. Addition of precursors such as urea, leucine, and valine affected growth and aroma production (144-147).

Kluyveromyces marxianus grown on cassava bagasse in SSF using packed bed column bioreactors under different aeration rates produced 11 volatile compounds, out of which nine were identified and two remained unidentified. Ethyl acetate, ethanol, and acetaldehyde were the major compounds produced, with 0.06 l/h/g aeration rate. Maximum TV concentrations were reached at 24 h with 0.06 l/h/g initial dry matter (IDM), and at 40 h for 0.12 l/h/g IDM. At 0.06 l/h/g aeration rate, ethyl acetate and ethanol were the compounds in highest and almost equivalent concentration (~30%) (148,149).

There are some other aroma compounds which can be produced in SSF. These include 2,5-dimethylpyrazine (2,5-DMP) by Bacillus natto (150) and tetramethylpyrazine (TTMP) by B. subtilis (151) on soybeans in SSF. Results demonstrated the suitability of SSF for their production.

Production of aroma compounds in SSF using naturally occurring substrates offers potential benefits in production of food and fruity aroma compounds for human consumption at low cost. One major difficulty in this regard is the isolation and recovery of compounds produced, especially if the compounds possess lower volatile temperature. A few attempts have been made to trap such compounds in suitable inert materials such as resins by adsorption. However, much remains to be done in this area.

Healthy Choice Coconut Oil

Healthy Choice Coconut Oil

For more than a decade, coconut oil has been used as a vital source of food for health and general well-being. Although once blindly labeled as a bad fat because of its saturated contents, many recent researches have found out that coconut oil possesses the nutrients necessary to maintain a well balanced and nutritious diet.

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