Ultrasound- and Microwave-Assisted Extraction of Pectin from Apple Pomace and Its Effect on the Quality of Fruit Bars

Abstract

The article investigates the process of pectin extraction using ultrasonic and microwave techniques from apple pomace generated during juice production in the context of circular bioeconomy. The extraction yield, equivalent mass, content of methoxyl groups, content of anhydrogalacturonic acid, and degree of esterification of pectin were investigated. These indicators varied depending on the parameters and extraction method. The resulting pectin displayed a co-extracted total polyphenol content (TPC) ranging from 2.16 to 13.05 mg GAE/g DW and a DPPH radical inhibition capacity of 4.32–18.86 μmol TE/g. It was found that the antioxidant activity of raw pectin is correlated with TPC and with the content of terminal groups released during the polysaccharide degradation process. The extracted pectin was used as a binding and coating agent for dried fruit bars. Evaluation of water activity (aw), TPC and total flavonoid content (TFC), together with sensory and microbiological analyses of the fruit bars over a period of 360 days, revealed a protective effect of pectin: reducing moisture loss, minimizing the degradation of bioactive compounds during storage, and maintaining the potential antioxidant activity of the product.

The Physicochemical Properties and Antioxidant Activities of the Hawthorn Pectin Extracted Using Ultra-High Pressure Assisted Acid Extraction (UPAAE)

“…The total polyphenols in hawthorn pectin were determined using the Folin-Ciocalteu method [22], with the following modifications to the procedure: 20 µL of gallic acid standard solution (40, 50, 80, 120, 140 mg/L) were mixed with 100 µL of Folin-Ciocalteu reagent (10%), and the mixture was stirred. After 5 min, 80 µL of Na 2 CO 3 solution and 50 µL of water were added, and the solution was left at room temperature for 1 h. Then, 200 µL of the solution were transferred to a microplate and the absorbance was measured at 765 nm using a microplate reader (1510; Thermo Fisher Scientific Instrument Co., Ltd., Shanghai, China).…”

Optimization of Ultrasonic-Assisted Extraction of Antioxidants in Apple Pomace (var. Belorusskoje malinovoje) Using Response Surface Methodology: Scope and Opportunity to Develop as a Potential Feed Supplement or Feed Ingredient

“…Utilization of fruit and vegetable waste as livestock feed offers a potential solution for global challenges such as climate change, urbanization, resource scarcity, and increase in current feed prices [1][2][3][4][5][6]. One of the common by-products of the fruit industry-apple pomace-exhibits promise as an alternative feed ingredient [5][6][7][8][9][10][11][12]. Apple pomace represents solid residue created during the extraction of juice from the apple.…”

“…It consists of pulp, skin, seeds, and stalk [7,13]. It has been estimated that the annual production of apple pomace can lead to up to 4 million tonnes [12]. This extensive production of apple pomace is especially alarming considering the high moisture content of apples, which makes them more prone to microbiological contamination and, consequently, environmental pollution [1,3,[14][15][16].…”

“…Research findings on the inclusion of apple pomace in animal diets are mixed; however, the health properties of apple pomace, like prebiotic and antioxidant effects, are encouraging [6,7,11,12,[17][18][19][20][21]. Antioxidant compounds protect animal health by detoxifying harmful free radicals [22,23].…”