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A strategy to optimize biotechnological process design is illustrated for the production of fructose-rich syrups via enzymatic hydrolysis of agave fructo-oligosaccharides. The optimization process includes ecological studies from natural fermentations leading to the selection of a strain with capacity for inulinase synthesis, and variable optimization for the synthesis, and enzymatic hydrolysis using the response surface methodology. The results lead to the selection of Kluyveromyces marxianus , endogenous strains isolated from aguamiel (natural fermented sugary sap from agave plants), as the main strain with high capacity for enzyme synthesis with inulinase activity. Production optimization at bioreactor level revealed that operation at 30.6 degrees C, 152 rpm, 1.3 VVM of aeration, and pH 6.3 leads to maximum inulinase synthesis, whereas 31 degrees C, 50 rpm, and pH 6.2 leads to maximum hydrolysis of agave fructo-oligosaccharides. HPLC analysis of the fructose-rich syrups obtained at these optimal conditions showed an average composition of 95% of fructose and 5% of glucose and the absence of sucrose. The analysis also revealed that the syrups are free of residues and toxic compounds, an undesirable occurrence often present when traditional methods based on thermal or acid hydrolysis are applied for their obtainment. Therefore, the product may be suitable for use as additive in many applications in the food and beverage industries.

A procedure for designing starter cultures for fermentation is illustrated for prickly pear wine production. The illustration includes kinetic studies on inoculated and spontaneous fermentation, microorganism identification studies based on molecular biology tools, and microbial ecology studies, which led to the selection of strains that are capable of synthesizing alcohol and desirable volatile compounds. Results show that a mixed starter inoculum containing Pichia fermentans and Saccharomyces cerevisiae leads to a fermented product that contains 8.37% alcohol (v/v). The gas chromatography and mass spectrometry (GC-MS) analysis shows the presence of 9 major volatile compounds (Isobutanol, Isopentanol, Ethyl acetate, Isoamyl acetate, Ethyl octanoate, Ethyl decanoate, Ethyl 9-decanoate, β-Phenylethyl acetate, and Phenylethyl alcohol) that have ethereal, fruity, aromatic notes that are considered to be essential for a fine wine flavor. These compounds harmonically synergize with the alcohol to produce a fermented product with a unique flavor and taste. Several assays using the mixed culture show that the process is stable, predictable, controllable, and reproducible. Moreover, the results show that a mixed culture leads to a broader range of aromatic products than that produced by a single, pure culture. Therefore, we conclude that combinations of Saccharomyces strains and non-Saccharomyces strains can be used to obtain high-quality fermented beverages from prickly pear juice.

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