Characterization of Orange Peel Waste and Valorization to Obtain Reducing Sugars.

José R Ayala,Mario A Curiel-Alvarez,Gisela Montero,José A León,Marcos A Coronado,Daniela G Montes,Carlos A Sagaste,Conrado García

doi:10.3390/molecules26051348

José R Ayala, Mario A Curiel-Alvarez + Show 6 more

Open Access

https://doi.org/10.3390/molecules26051348

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Abstract

Annually, millions of tons of foods are generated with the purpose to feed the growing world population. One particular eatable is orange, the production of which in 2018 was 75.54 Mt. One way to valorize the orange residue is to produce bioethanol by fermenting the reducing sugars generated from orange peel. Hence, the objective of the present work was to determine the experimental conditions to obtain the maximum yield of reducing sugars from orange peel using a diluted acid hydrolysis process. A proximate and chemical analysis of the orange peel were conducted. For the hydrolysis, two factorial designs were prepared to measure the glucose and fructose concentration with the 3,5-DNS acid method and UV-Visible spectroscopy. The factors were acid concentration, temperature and hydrolysis time. After the hydrolysis, the orange peel samples were subjected to an elemental SEM-EDS analysis. The results for the orange peel were 73.530% of moisture, 99.261% of volatiles, 0.052% of ash, 0.687% of fixed carbon, 19.801% of lignin, 69.096% of cellulose and 9.015% of hemicellulose. The highest concentration of glucose and fructose were 24.585 and 9.709 g/L, respectively. The results highlight that sugar production is increased by decreasing the acid concentration.

Highlights

In 2018, the United Nations Food and Agriculture Organization (F.A.O.) [1] estimated a world citrus production of 104.15 Mt, with 75.54 Mt corresponding to orange
Under the selected parameters of the design of experiments, the maximum concentration of glucose and fructose was achieved with an acid concentration of 0.5%, at 125 ◦C for 2 h
This does not mean that they are the best conditions to operate a hydrolysis process applied to orange peel waste

Summary

Introduction

In 2018, the United Nations Food and Agriculture Organization (F.A.O.) [1] estimated a world citrus production of 104.15 Mt, with 75.54 Mt corresponding to orange. During 2018, the largest orange producers worldwide were Brazil, China, India, USA and Mexico, achieving 58.10% of the total orange production. In the same year Mexico produced 4.74 Mt of orange, which represents 6.3% of the world total production [2]. Orange production is increasing year over year. The wastes that are generated from the orange industry include seeds, pulp, albedo and peel. Not all waste is used, resulting in non-hazardous waste with revalorization potential

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