info:eu-repo/semantics/conferencePoster
Phytic acid quantification in agroindustrial residues and their potential as inducers for phytase production in solid state fermentation
Autor
ROSA MARIA CAMACHO RUIZ
Institución
Resumen
Researches has been focused in phytase production from agroindustrial residues rich in phytic acid, but phytic acid extracts from row material have not been used as inducers.
Analytical determination of phytate levels in feed raw materials is considered “primitive”, since most methods for photometrical determination of phytate are based on indirect
measurements (inositol phosphate) or establishment of stoichiometric ratio between phytate and some cations easy to determine with a direct tool. Several methods have been
published for phytate quantification. Most of them (Bartlett, 1959) with acidic extraction carried out with HCl, H2SO4, or trichloroacetic acid (TCA) with different concentrations and
extraction times, followed by precipitation with Fe3+ [1]. Unprecipitated ferric ions are determined by spectrophotometry. The difference between initial and remaining ferric ion
concentration is then used to calculate phytate concentration. Acid extraction is preferable, because raw materials such as wheat might contain high levels of endogenous
phytase, which could degrade phytate if allowed. A well-known photometrical phytate method is the protocol developed by Haug and Lantzsch that uses 2,2′-bipyridine as a
complexing chromogenic agent to quantify ferric ions [2]. In the present study phytic acid extracts were obtained from agroindustrial residues: corn husk, cottonseed meal and
wheat bran. The Haug-Lantzsch modified method was used for quantification. Subsequently phytic acid extracts were tested as inducers for phytase production by solid state
fermentation. The best conditions for extracting phytic acid were: 0.2M of HCl, 25°C and 1:20 ratio for the three agroindustrial residues, finding 0.57 %, 0.45 % and 0.67 % of
phytic acid for corn husk, cottonseed meal and wheat bran, respectively (Fig. 1). The three extracts obtained were assayed as inducers for phytase production in SSF. The
maximum phytase activity reached was 0.39±0.09 U/gDM at 24 h of fermentation using a wheat bran extract as inducer, followed by corn husk extract with 0.35±0.01 U/gDM at
24 h of fermentation; cottonseed meal extract used as SSF inducer, does not present significant phytase activity (Fig. 2).