Comparison of Biological and Chemical Pretreatment on Coproduction of Pectin and Fermentable Sugars from Apple Pomace

Challenging DESs and ILs in the valorization of food waste: a case study

In this study, the efficacy of two of the best performing green solvents for the fractionation of lignocellulosic biomass, cholinium arginate (ChArg) as biobased ionic liquid (Bio-IL) and ChCl:lactic acid (ChCl:LA, 1:10) as natural deep eutectic solvent (NADES), was investigated and compared in the pretreatment of an agri-food industry waste, apple fibers (90°C for 1 h). For the sake of comparison, 1-butyl-3-methylimidazolium acetate (BMIM OAc) as one of the best IL able to dissolve cellulose was also used. After the pretreatment, two fractions were obtained in each case. The results gathered through FTIR and TG analyses of the two materials and the subsequent DNS assay performed after enzymatic treatment led to identify ChArg as the best medium to delignify and remove waxes, present on the starting apple fibers, thus producing a material substantially enriched in cellulose (CRM). Conversely, ChCl:LA did not provide satisfactorily results using these mild conditions, while BMIM OAc showed intermediate performance probably on account of the reduced crystallinity of cellulose after the dissolution-regeneration process. To corroborate the obtained data, FTIR and TG analyses were also performed on the residues collected after the enzymatic hydrolysis. At the end of the pretreatment, ChArg was also quantitatively recovered without significant alterations.

Physicochemical Characteristics, Antioxidant Properties and Consumer Acceptance of Greek Yogurt Fortified with Apple Pomace Syrup

Despite having high polyphenolic phytochemicals and functional components, apple pomace (AP) is often discarded in landfills, leading to pollution. The study aimed to find a sustainable application for AP in Greek yogurt fortified with AP syrup (APS). Physicochemical characteristics and antioxidant properties were analyzed for APS (APS0.00, APS1.25, APS2.50, APS3.75, APS5.00). As the AP content in the syrup increased, moisture content, titratable acidity, and viscosity significantly increased (p < 0.05). The total polyphenols and flavonoid content of APS increased with increasing AP content. In Greek yogurt fortified with APS (APY), reducing sugar content (0.55 mg/mL to 0.71 mg/mL) significantly increased with fermentation time and AP content, whereas pH level (6.85 to 4.28) decreased. The antioxidant activities by DPPH radical scavenging activity, ABTS radical scavenging activity, ferric reducing antioxidant power, and reducing power were also significantly increased with the AP content and fermentation time. In the consumer acceptance test of APY, APY1.25 had significantly high scores in overall acceptance, taste acceptance, and aftertaste acceptance with purchase intent (p < 0.05). The Greek yogurt fortified with APS as functional food had improved antioxidant properties and consumer acceptance, suggesting the possibility of developing sustainable AP products.

Revalorization of sunflower stalk pith as feedstock for the coproduction of pectin and glucose using a two-step dilute acid pretreatment process

BACKGROUND

Sunflower stalk pith, residue from the processing of sunflower, is rich in pectin and cellulose, thereby acting as an economic raw material for the acquisition of these compounds. In order to increase the commercial value of sunflower processing industry, a two-step dilute sulfuric acid treatment process was conducted on spent sunflower stalk pith to obtain the value-added products, pectin and glucose.

RESULTS

In this study, pectin was firstly extracted under mild acid condition to avoid pectin degradation, which was conducted at 90 °C with a pH of 2.0 for 2 h, and ~0.14 g/g of pectin could be recovered. Then the remaining solids after pectin extraction were subjected to the reinforced treatment process with 0.75% H₂SO₄ at 150 °C for 30 min to further improve enzymatic hydrolysis efficiency. Moreover, by combining a fed-batch enzymatic hydrolysis strategy, a solid loading content of 16% was successfully achieved and the glucose titer reached 103.1 g/L with a yield of 83.6%.

CONCLUSION

Finally, ~140 g pectin and 260 g glucose were produced from 1 kg of raw sunflower stalk pith using the integrated biorefinery process. This work puts forward a two-step dilute acid pretreatment combined with enzymatic hydrolysis method to produce pectin and glucose from sunflower spent waste.

The Enzymatic Digestion of Pomaces From Some Fruits for Value-Added Feed Applications in Animal Production

With the noticed steady increase of global demand for animal proteins coupled with the current farming practices falling short in fulfilling the requested quantities, more attention is being paid for means and methods intended to maximize every available agricultural-resource in a highly sustainable fashion to address the above growing gap between production and consumers' demand. Within this regard, considerable efforts are being invested either in identifying new animal feed ingredients or maximizing the utilization of already established ones. The public preference and awareness of the importance of using waste products generated by fruit-dependent industries (juice, jams, spirits, etc.) has improved substantially in recent years where a genuine interest of using the above waste(s) in meaningful applications is solidifying and optimization-efforts are being pursued diligently. While many of the earlier reported usages of fruit pomaces as feedstuffs suggested the possibility of using minimally processed raw materials alone, the availability of exogenous digestive and bio-conversion enzymes is promising to take such applications to new un-matched levels. This review will discuss some efforts and practices using exogenous enzymes to enhance fruit pomaces quality as feed components as well as their nutrients' accessibility for poultry and swine production purposes. The review will also highlight efforts deployed to adopt numerous naturally derived and environmentally friendly catalytic agents for sustainable future feed applications and animal farming-practices.