Effect of Ultrasound Assisted Extraction and Acid Type Extractant on Pectin from Industrial Tomato Waste

Abstract

Pectin can be extracted from many fruits and also by-product from industry. Tomato can be produced into many products led to large amount of waste. This work aims to extract pectin from tomato waste achieved by tomato paste industry using Ultrasound Assisted Extraction (UAE) method (temperature of 40, 60 or 80 o C and time of 10, 15, 20 or 30 min, at pH of 2.5 and solid: liquid ratio of 1:40 w/v) using citric acid as an extractant. Moreover, the extractant (citric acid, hydrochloric acid and nitric acid) for pectin extraction under best UAE condition were compared, as well as physical and chemical properties of obtained pectin were determined. The results showed that the temperature of 80 o C and time of 20 min providing the highest pectin yield with shorter time. Moreover, the citric acid gave the highest yield compare to the other acid extractant. Citric acid extraction gave pectin with higher anhydrouronic acid content (31.59%), however, it gave comparable methoxyl content compare to others. Furthermore, citric acid extraction pectin could be categorized as low DM pectin while the others gave the high DM pectin. All obtained pectin were highly color and the a* of pectin extracted with citric acid was the lowest. Nevertheless, the extractant was not significantly impact to lycopene content (6.65-9.35 mg/100g pectin). This suggest that UAE method together with citric acid extraction could be used as an efficient method for pectin extraction with interestingly lycopene content.

Effect of Ultrasound-Assisted, Microwave-Assisted and Ultrasound-Microwave-Assisted Extraction on Pectin Extraction from Industrial Tomato Waste

“…Previously, pectin has been successfully extracted from industrial tomato waste by UAE at 80 • C for 20 min with citric acid at a pH of 2.5, which gave the highest yield (10%) and this yield was higher than any other mineral acid, hydrochloric acid, or nitric acid had given [7]. However, this yield was still lower.…”

“…A tomato which cultivated in the world has been used for produce tomato food products for almost 40 million tons in 2021 [2]. Tomato waste from commercial tomato manufacturing has been used as raw material for the extraction of bioactive compounds, such as lycopene extraction [3,4], phenolic extraction [1], and pectin extraction [5][6][7]. Grassino et al [6] extracted pectin from tomato peels by reflux at 90 • C for 24 and 12 h and ammonium oxalate/oxalic acid used as solvent.…”

“…Citric acid is an organic acid with a chelating property and has been studied for use as a solvent for pectin extraction, such as sugar beets [11], mango peels [12,13]. It was reported that the citric acid had given a higher pectin yield than mineral acid [7,12]. Many techniques have been developed for pectin extraction, such as microwave heating, ultrasonication, and a super high-frequency electromagnetic field [14].…”

“…The UAE has been used for bioactive compound extraction due to its shorter period, higher yield, lower energy, and solvent consumptions. Many research studies have been conducted on UAE for pectin extraction from many plants, such as mango peels [13], jackfruit peels [17], and tomato waste from the canning industry [5] and from the tomato paste industry [7]. Grassino et al [5] extracted pectin from tomato wastes from the canning industry by using ultrasound techniques at the extraction temperatures of 60 • C and 80 • C with ammonium oxalate/oxalic acid, in which these conditions gave a comparable yield, but took a shorter time.…”

“…Grassino et al [5] extracted pectin from tomato wastes from the canning industry by using ultrasound techniques at the extraction temperatures of 60 • C and 80 • C with ammonium oxalate/oxalic acid, in which these conditions gave a comparable yield, but took a shorter time. Sengkhamparn et al [7] reported that the appropriate UAE condition for pectin extraction from tomato waste, derived from the tomato paste industry, was a temperature of 80 • C and a time of 20 min with citric acid at a pH of 2.0. In this work, the pectin yield was slightly low.…”