Agroindustrial Byproducts for the Generation of Biobased Products: Alternatives for Sustainable Biorefineries

Abstract

The integrated approach in biorefinery mainly involves the utilization of various agroindustrial byproducts such as raw materials for the production of several biobased products like biofuels, bioenergy, and other high-value chemicals. Biofuels are the backbone of biorefineries, however, production of value-added biomolecules such as biopigments, biopolymers, biosurfactants, and nutritional yeast has been attracting great attention. The production of these biomolecules using traditional approaches has been extensively studied in the last few years owing to their promising application in different industries such as chemical, food/feed, and pharmaceuticals for the development of novel products for mankind. Moreover, the production of such biomolecules using lignocellulosic, starchy, and some other agroindustrial byproducts is still not fully explored. Hence, there is a huge scope in the development of sustainable biorefining approaches to make the technology cost-effective. The lignocellulosic biomasses usually used in biorefineries are mainly composed of cellulose, hemicellulose, and lignin, whereas starchy materials, besides starch, usually contain, protein, lipids, and some micronutrients. The processing of these biomasses through successive steps like pretreatments, enzymatic hydrolysis, and fermentation is essentially required to obtained final biobased products. Considering certain bottlenecks of above-mentioned conventional biorefineries approaches, new technologies have been proposed for the improved pretreatment of biomass and efficient enzymatic hydrolysis in order to minimize the concentration of toxic inhibitors in resulting hydrolysate. In this review, we highlighted the different agroindustrial byproducts and their applications for the production of valuable biorefinery products.

A New Approach for the Production of Selenium-Enriched and Probiotic Yeast Biomass from Agro-Industrial by-Products in a Stirred-Tank Bioreactor

“…The use of crop by-products represents an important technological advance since most technologies are focused on the development of integrated crop-livestock systems to optimize the yields [ 55 ]. Thus, crop wastes are produced in large amounts due to the improvement of agriculture activities and represent important sources of nutrients that can be used for microbial growth [ 33 ]. S. cerevisiae is an important microorganism used for bioethanol production due to its ability to ferment sugars and its high ethanol productivity and tolerance [ 56 ].…”

“…Soybean bran was hydrolysate with H 2 SO 4 1% ( w / v ), 1:5 ( w / v ) (dry mass) in Erlenmeyer flasks in an autoclave at 121 °C, 15 min. After hydrolysis, both hydrolysates were filtered in cotton cloth, had their pH adjusted with 6.5 mol/L NaOH until pH 5.5, were centrifuged (2000× g , 10 min), sterilized (1.1 atm, 15 min), and centrifuged aseptically in these same conditions [ 33 ]. Sugarcane molasses was diluted until 50 g/L of reducing sugars, the pH was adjusted to 5.5 using 6.5 mol/L NaOH, and sterilized at 1.1 atm for 15 min ( Figure 2 ).…”

“…The inoculum was prepared by the transference of two loopful of colonies of each strain from YPMG agar to YPG broth containing (g/L) glucose 30.0, peptone 20.0, and yeast extract 10.0. Erlenmeyer flasks were filled with 40% working volume with YPG broth and incubated in an orbital shaker at 30 °C, 200 rpm for 24 h [ 33 ]. After 24 h, the inoculum was centrifuged at 2000× g for 10 min for cell recovery, and the yeast biomass was washed, suspended in sterile distilled water, and adjusted for 1 × 10 8 cell/mL by counting cells in Agasse Lafont-R chamber (0.0025 mm 2 × 0.1 mm 3 ) (Optik Labor, Lancing, United Kingdom) under 400× magnification in an optical microscope [ 31 ].…”

“…Bran is an agro-industrial by-product from grain manufacturing and, though it is partially used as feed, a large amount remains as a residue. This biomass is rich in macronutrients and micronutrients and can be used as both carbon and nitrogen source for microorganisms during the production of several bioproducts such as Se-enriched yeast, single-cell protein, biopigments, β-glucans, ethanol, xylitol [ 30 , 31 , 32 , 33 ]. Agro-industrial by-products composition may vary depending on the region, however, the basic constituents of each by-product remain in the same range [ 33 , 34 ].…”

“…This biomass is rich in macronutrients and micronutrients and can be used as both carbon and nitrogen source for microorganisms during the production of several bioproducts such as Se-enriched yeast, single-cell protein, biopigments, β-glucans, ethanol, xylitol [ 30 , 31 , 32 , 33 ]. Agro-industrial by-products composition may vary depending on the region, however, the basic constituents of each by-product remain in the same range [ 33 , 34 ]. A biomass pretreatment is necessary to release sugars and nutrients before fermentation, and the acid pretreatment is a low-cost and efficient method for bran such as corn bran [ 35 ].…”