An Electrochemical Impedance Spectroscopy System for Monitoring Pineapple Waste Saccharification

Abstract

Electrochemical impedance spectroscopy (EIS) has been used for monitoring the enzymatic pineapple waste hydrolysis process. The system employed consists of a device called Advanced Voltammetry, Impedance Spectroscopy & Potentiometry Analyzer (AVISPA) equipped with a specific software application and a stainless steel double needle electrode. EIS measurements were conducted at different saccharification time intervals: 0, 0.75, 1.5, 6, 12 and 24 h. Partial least squares (PLS) were used to model the relationship between the EIS measurements and the sugar determination by HPAEC-PAD. On the other hand, artificial neural networks: (multilayer feed forward architecture with quick propagation training algorithm and logistic-type transfer functions) gave the best results as predictive models for glucose, fructose, sucrose and total sugars. Coefficients of determination (R2) and root mean square errors of prediction (RMSEP) were determined as R2 > 0.944 and RMSEP < 1.782 for PLS and R2 > 0.973 and RMSEP < 0.486 for artificial neural networks (ANNs), respectively. Therefore, a combination of both an EIS-based technique and ANN models is suggested as a promising alternative to the traditional laboratory techniques for monitoring the pineapple waste saccharification step.

Microwave-Assisted Alkali Pretreatment for Enhancing Pineapple Waste Saccharification

“…Figure 5 shows the HMF content of MAP and subsequently saccharified waste. Furfural was not detected in the liquid phase of the analyzed waste, which could be due to the low pentose content in the initial waste that can be considered negligible (Conesa et al 2016). In addition, the microwave pretreatment in an alkaline medium caused a marked increase in HMF content, such that both nominal power applied and exposure time were significant.…”

“…At a low microwave power (2.125 W/g), the highest increases in fermentable (32.6%) and total sugars (33.6%) were obtained at t = 10 s, but there were no statistically significant differences with the results at t = 5 s and t = 15 s. At an intermediate power (4.25 W/g), the largest increases in fermentable (27.9%) and total sugars (26.7%) were achieved at t = 5 s, although no statistically significant differences were observed with the results at t = 10 s and 20 s. The highest increases of fermentable (35.7%) and total sugars (33.5%) were obtained at t = 5 s when high microwave power was applied. However, these values showed no statistically significant differences with any bioresources.com Conesa et al (2016). "Microwave-alkali pretreatment," BioResources 11(3), 6518-6531.…”

“…2. Thermal images and temperature scales corresponding to the bottom surface of the recipient containing MAP pineapple waste at different powers: 2.125 W/g, 4.25 W/g, and 6.375 W/g, and exposure times: 10 s, 60 s, 120 s, and 180 s; white cross, hot spot (HS) PEER-REVIEWED ARTICLE bioresources.com Conesa et al (2016). "Microwave-alkali pretreatment," BioResources 11(3), 6518-6531.…”

“…In this case, the obtained values were not sufficient to inhibit subsequent fermentation. Conesa et al (2016). "Microwave-alkali pretreatment," BioResources 11(3), 6518-6531.…”

“…Some useful components and sugars might be decomposed by pretreatments at high temperatures with high microwave power and long exposure times (Zhu et al 2005). bioresources.com Conesa et al (2016). "Microwave-alkali pretreatment," BioResources 11(3), 6518-6531.…”