Punica granatum waste to ethanol valorisation employing optimized levels of saccharification and fermentation

Asma Chaudhary; Afia Muhammad Akram; Ayesha Aihetasham; Zawar Hussain; Afshan Syed Abbas; Rahat Abdul Rehman; Qurat-Ul-Ain Ahmad; Anjum Tahira; Ayesha Saleem; Samina Qamer; Youssef Alghamdi; Samy F Mahmoud; Samy Sayed

doi:10.1016/j.sjbs.2021.04.049

Punica granatum waste to ethanol valorisation employing optimized levels of saccharification and fermentation

Saudi J Biol Sci. 2021 Jul;28(7):3710-3719. doi: 10.1016/j.sjbs.2021.04.049. Epub 2021 Apr 24.

Authors

Affiliations

¹ Department of Zoology, Division of Science and Technology, University of Education, Lahore 54770, Pakistan.
² Department of Zoology, University of the Punjab, Lahore, Pakistan.
³ Department of Zoology, University of Education, Lower Mall Campus, Lahore, Pakistan.
⁴ Department of Forensic Sciences, University of Health Sciences, Lahore, Pakistan.
⁵ Department of Botany, University of Okara, Okara, Pakistan.
⁶ Department of Zoology, Government College University, Faisalabad, Pakistan.
⁷ Department of Biology, Turabah University College, Taif University, 21995, Saudi Arabia.
⁸ Department of Biotechnology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia.
⁹ Department of Science and Technology, University College-Ranyah, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia.

Abstract

Pomegranate peels (PPW) as municipal waste is inexpensive biomass that could be a renewable source of sugars particularly rich in hemicellulosic contents. The subsequent conversion of available sugars in PPW can provide prospective strategy for cost-effective bioenergy production. In this study, an experimental setup based on CCD was implemented with the aim of bioconversion of biomass into bioethanol. The factors considered were Hydrochloric acid concentration (X₁), the hydrolysis temperature (X₂) and time (X₃) for optimization with dilute Hydrochloric acid (HCl) saccharification. The present study investigates the optimised level of bioethanol synthesis from acid pre-treated PPW explained by RSM. Subsequently, three yeasts viz. Saccharomyces cerevisiae K7, Metschnikowia sp. Y31 and M. cibodasensis Y34 were utilized for fermentation of acid hydrolysed and detoxified feed stocks. Optimum values of reducing sugars 48.02 ± 0.02 (gL^-1) and total carbohydrates 205.88 ± 0.13 (gL^-1) were found when PPW was hydrolyzed with 1% HCl concentration at 100˚C of temperature for 30 min. Later on, fermentation of PPWH after detoxification with 2.5% activated charcoal. The significant ethanol (g ethanol/g of reducing sugars) yields after fermentation with Metschnikowia sp. Y31 and M. cibodasensis Y34 found to be 0.40 ± 0.03 on day 5 and 0.41 ± 0.02 on last day of experiment correspondingly. Saccharomyces cerevisiae K7 also produce maximum ethanol 0.40 ± 0.00 on last day of incubation utilizing the PPWH. The bioconversion of commonly available PPW into bioethanol as emphasize in this study could be a hopeful expectation and also cost-effective to meet today energy crisis.

Keywords: ANOVA, Analysis of variance; CCD, Central composite design; DNS, Dinitrosalicyclic acid; Ethanologenesis; Fermentation; MYG, Malt yeast glucose; Metschnikowia; Optimization; PPW, Pomegranate peel waste; PPWH, Pomegranate peel waste hydrolyzate; RSM, Response surface methodology; RT, Room temperature; Sacharrification.