Ecuador is an agricultural country, which has an actual production of starch obtained from cassava. Tuber processing residues do not have an economic impact; for example, the cassava bagasse, only used for plant fertilization and animal feeding. This project aimed to study the influence of the fermentation variables (pH and agitation), on the lactic acid production. Enzymatic hydrolysis of cassava bagasse starch for the varieties INIAP 650 and INIAP 651 was performed using α-amylase and glucoamylase. Then, glucose was fermented by Lactobacillus leichmannii ATCC 7830 strains, varying conditions such as agitation (150 rpm and absence) and pH (4.5, 5.0, and 5.5). Finally, the determination of lactic acid was performed by potentiometric and FTIR analysis. Conversions of cassava bagasse to reduced sugars were 71.66 and 85.05 % for INIAP 650 and INIAP 651 varieties. The best lactic acid concentrations were 27.62 and 33.48 g/L, obtained at pH 5.5 and agitation, for INIAP 650 and INIAP 651 varieties. Qualitative analysis conducted by FTIR spectrophotometry confirmed the presence of lactic acid in the reacted products. Lactic acid production from cassava bagasse starch could contribute to the Manabí and Esmeraldas provinces of Ecuador's economic development.

Manuscript Click here to download Manuscript Revised text.docx Click here to view linked References 2 Abstract 39 40 A nitrate reductase immobilized system with an oxygen electrode has been developed and 41 optimised to determine the nitrate content in dry-cured ham. The obtained amperometric 42 signal was recorded at s in the immobilised nitrate reductase sensor and the reaction 43 rates (slope) were related to the nitrate content. A linear relationship between the 44 reduction nitrate rate by action of nitrate reductase and the nitrate concentration was 45 found within the range 10-70µM (R 2 =0.9761). The immobilized enzyme showed a high 46 specificity and sensibility and was stable enough to allow the reutilization of the 47 HPLC revealed very good agreement (R 2 = 0.971). The use of this sensor may constitute 51 an interesting and valid alternative for the quantification of nitrate in dry cured ham.

Manuscript Click here to download Manuscript Paper rev FT.docx Click here to view linked References 2 40 41 Abstract 42 43 An enzymatic sensor employing lysine oxidase (LOx) with the immobilized enzyme 44 system by crosslinking with glutaraldehyde using an immunodyne ABC nylon 45 membrane, in combination with an oxygen electrode has been optimised to determine 46 the lysine content in dry-cured ham and dry-fermented sausage at different cured times. 47 The amperometric signal obtained due to the oxygen depletion (consumed oxygen) 48 during the lysine oxidation was recorded at 200 s in the immobilised enzyme sensor at 5 49 s and the reaction rates (slope) were related to the lysine content. A linear relationship 50 between the consumed oxygen as a function of time (mg O2/L*s-1) and the lysine 51 concentration in the range 10-250 M (R 2 =0.9946) for the immobilised enzyme system 52 were found. The immobilised enzyme sensor showed a high specificity and sensibility. 53 Nevertheless, the stability of the immobilized enzyme at the assay temperature was very 54 poor and thus a new membrane was required for each analysis. The analysis of lysine 55 with the immobilized enzyme system in cured meat samples revealed very good 56 agreement with the determination performed through standard HPLC methodology, 57 which validated the use of this sensor as an alternative technique to evaluate cured meat 58 quality.