Ultrasound assisted extraction and characterization of pectin from tomato waste

Physicochemical and in vitro antioxidant properties of pectin extracted from hot pepper (Capsicum annuum L. var. acuminatum (Fingerh.)) residues with hydrochloric and sulfuric acids

BACKGROUND

Transformation of hot pepper residues to value-added products with concomitant benefits on environmental pollution would be of great value to capsicum oleoresin manufacturers. Pectin, a soluble dietary fiber with multiple functions, from hot pepper residues was investigated in this study.

RESULTS

The extraction of hot pepper pectin using hydrochloric acid was first optimized using response surface methodology (RSM). The most efficient parameters for maximum hot pepper pectin yield (14.63%, dry basis) were a pH of 1.0, a temperature of 90 °C, an extraction time of 2 h and a liquid-to-solid ratio of 20 L g^-1 . The pectin was mainly composed of uronic acids, and the major neutral sugars were galactose and glucose. The structure of hot pepper pectin was characterized by homogalacturonan and rhamnogalacturonan I elements. The physicochemical properties of hot pepper pectin extracted by sulfuric acid and hydrochloric acid were further investigated. The content of protein and degree of esterification in hot pepper pectin extracted with sulfuric acid solution (SP) were higher (P < 0.05) than those in that extracted with hydrochloric acid solution (HP), while the mean molecular weight of SP was lower than that of HP. Compared with HP, SP exhibited higher viscosity and better emulsifying property.

CONCLUSION

Based on the yield and physicochemical properties of hot pepper pectin, hot pepper residues would be a new source to obtain pectin, and SP would be more preferred than HP. © 2017 Society of Chemical Industry.

Isolation and Characterization of Cellulose from Different Fruit and Vegetable Pomaces

A new fractionation process was developed to achieve valorization of fruit and vegetable pomaces. The importance of the residues from fruits and vegetables is still growing; therefore; the study presents the novel route of a fractioning process for the conversion of agro-industrial biomasses, such as pomaces, into useful feedstocks with potential application in the fields of fuels, chemicals, and polymers. Hence, the biorefinery process is expected to convert them into various by-products offering a great diversity of low-cost materials. The final product of the process is the cellulose of the biofuel importance. The study presents the novel route of the fractioning process for the conversion of agro-industrial biomasses, such as pomaces, into useful feedstocks with a potential application in the fields of fuels, chemicals, and polymers. Therefore the aim of this paper was to present the novel route of the pomaces fraction and the characterization of residuals. Pomaces from apple, cucumber, carrot, and tomato were treated sequentially with water, acidic solution, alkali solution, and oxidative reagent in order to obtain fractions reach in sugars, pectic polysaccharides, hemicellulose, cellulose, and lignin. Pomaces were characterized by dry matter content, neutral detergent solubles, hemicellulose, cellulose, and lignin. Obtained fractions were characterized by the content of pectins expressed as galacturonic acid equivalent and hemicelluloses expressed as a xyloglucan equivalent. The last fraction and residue was cellulose characterized by crystallinity degree by X-ray diffractometer (XRD), microfibril diameter by atomic force microscope (AFM), and overall morphology by scanning electron microscope (SEM). The hemicelluloses content was similar in all pomaces. Moreover, all the materials were characterized by the high pectins level in extracts evaluated as galacturonic acid content. The lignins content compared with other plant biomasses was on a very low level. The cellulose fraction was the highest in cucumber pomace. The cellulose fraction was characterized by crystallinity degree, microfibril diameter, and overall morphology. Isolated cellulose had a very fine structure with relatively high crystalline index but small crystallites.

Acoustic cavitation assisted extraction of pectin from waste grapefruit peels: A green two-stage approach and its general mechanism

In the present study, acoustic cavitation assisted extraction (ACAE) which is a green approach was used for two-stage extraction of pectin from waste grapefruit peels regarding the specific two stages and different peel particle sizes. The yields, physicochemical properties and structure prediction of pectin from different peel particle sizes and different stages by two methods were compared. Highest pectin yield of 23.49% was achieved at the peel size of 0.9mm and was slightly higher than the yield of 23.44% at finer particle size. ACAE achieved four times higher yield compared with conventional heating method (CHE) at the second stage. ACAE pectin which had lower molecular weight and degree of methoxylation was richer in rhamnogalacturonan-I (RG-I) region with long side chains compared with CHE pectin from chemical and FT-IR analysis. Based on the results, a potential general mechanism for ACAE of plant cell wall viscous polysaccharides was discussed in terms of the effects of cavitation on the swelling index and morphological study of residue to reveal the "barrier effect" during the process. Furthermore, the energy consumption for ACAE was significantly lower than the conventional method, indicating its promising application in industrial scale.

Re-evaluation of pectin (E 440i) and amidated pectin (E 440ii) as food additives

Following a request from the European Commission, the EFSA Panel on Food Additives and Nutrient sources added to Food (ANS) was asked to deliver a scientific opinion on the re-evaluation of pectin (E 440i) and amidated pectin (E 440ii) as food additives. An acceptable daily intake (ADI) 'not specified' was allocated by the Scientific Committee for Food (SCF) for E 440i and E 440ii. Pectin and amidated pectin would not be absorbed intact, but extensively fermented by intestinal microbiota in animals and humans; products formed from pectins in the gastrointestinal tract are similar to manufactured pectin-derived acidic oligosaccharides (pAOS). There is no indication of genotoxicity for pectin and amidated pectin, although the available data were limited. No adverse effects were reported in a chronic toxicity study in rats at levels up to 5,000 mg pectin/kg bw per day, the highest dose tested. No treatment-related effects were observed in a dietary one-generation reproductive toxicity study with pAOS in rats at up to 6,200 mg/kg body weight (bw) per day, the highest dose tested. The Panel did not consider E 440i and E 440ii as having allergenic potential. A dose of 36 g/day (equivalent to 515 mg/kg bw per day) for 6 weeks in humans was without adverse effects. Exposure to pectins from their use as food additives ranged up to 442 mg/kg bw per day for toddlers at the 95th percentile (brand-loyal scenario). The Panel concluded that there is no safety concern for the use of pectin (E 440i) and amidated pectin (E 440ii) as food additives for the general population and that there is no need for a numerical ADI.

Landmarks in the historical development of twenty first century food processing technologies

Over a course of centuries, various food processing technologies have been explored and implemented to provide safe, fresher-tasting and nutritive food products. Among these technologies, application of emerging food processes (e.g., cold plasma, pressurized fluids, pulsed electric fields, ohmic heating, radiofrequency electric fields, ultrasonics and megasonics, high hydrostatic pressure, high pressure homogenization, hyperbaric storage, and negative pressure cavitation extraction) have attracted much attention in the past decades. This is because, compared to their conventional counterparts, novel food processes allow a significant reduction in the overall processing times with savings in energy consumption, while ensuring food safety, and ample benefits for the industry. Noteworthily, industry and university teams have made extensive efforts for the development of novel technologies, with sound scientific knowledge of their effects on different food materials. The main objective of this review is to provide a historical account of the extensive efforts and inventions in the field of emerging food processing technologies since their inception to present day.

Emerging concepts in the nutraceutical and functional properties of pectin-A Review

Pectin is a structural heteropolysaccharide found ubiquitously in terrestrial plants. It finds diverse food applications such as that of a gelling agent, stabilizer, and fat replacer. In the pharmaceutical arena, pectin exhibits a number of functions, from decreasing blood fat to combating various types of cancers. This review shows the shift of pectin from its conventional roles to its progressive applications. Insights into the advances in the production of pectin, the role it plays as a nutraceutical, possible prebiotic potential and a delivery vehicle for probiotics, and food applications are highlighted. Bioactive and functional properties of pectin are discussed and how the structural built up defines them, is emphasized. As a biopolymer, the applications of pectin in active packaging are also mentioned.

Side Streams of Plant Food Processing As a Source of Valuable Compounds: Selected Examples

Industrial processing of plant-derived raw materials generates enormous amounts of by-products. On one hand, these by-products constitute a serious disposal issue because they often emerge seasonally and are prone to microbial decay. On the other hand, they are an abundant source of valuable compounds, in particular secondary plant metabolites and cell wall materials, which may be recovered and used to functionalize foods and replace synthetic additives with ingredients of natural origin. This review covers 150 references and presents select studies performed between 2001 and 2016 on the recovery, characterization, and application of valuable constituents from grape pomace, apple pomace, potato peels, tomato pomace, carrot pomace, onion peels, by-products of citrus, mango, banana, and pineapple processing, side streams of olive oil production, and cereal by-products. The criteria used were economic importance, amounts generated, relevance of side streams as a source of valuable compounds, and reviews already published. Despite a plethora of studies carried out on the utilization of side streams, relatively few processes have yet found industrial application.

Pectin as a rheology modifier: Origin, structure, commercial production and rheology

Pectins are a diverse family of biopolymers with an anionic polysaccharide backbone of α-1,4-linked d-galacturonic acids in common. They have been widely used as emulsifiers, gelling agents, glazing agents, stabilizers, and/or thickeners in food, pharmaceutical, personal care and polymer products. Commercial pectin is classified as high methoxy pectin (HMP) with a degree of methylation (DM) >50% and low methoxy pectin (LMP) with a DM <50%. Amidated low methoxy pectins (ALMP) can be obtained through aminolysis of HMP. Gelation of HMP occurs by cross-linking through hydrogen bonds and hydrophobic forces between the methyl groups, assisted by a high co-solute concentration and low pH. In contrast, gelation of LMP occurs by the formation of ionic linkages via calcium bridges between two carboxyl groups from two different chains in close proximity, known as the 'egg-box' model. Pectin gels exhibit Newtonian behaviour at low shear rates and shear-thinning behaviour when the shear rate is increased. An overview of pectin from its origin to its physicochemical properties is presented in this review.

Characterization and functional properties of mango peel pectin extracted by ultrasound assisted citric acid

Pectin was extracted from 'Tainong No. 1' mango peels, using a chelating agent-citric acid as extraction medium by ultrasound-assisted extraction (UAE) and conventional extraction (CE) at temperatures of 20 and 80°C. Chemical structures, rheological and emulsifying properties of mango peel pectins (MPPs) were comparatively studied with laboratory grade citrus pectin (CP). All MPPs exhibited higher protein content (4.74%-5.94%), degree of methoxylation (85.43-88.38%), average molecular weight (Mw, 378.4-2858kDa) than the CP, but lower galacuronic acid content (GalA, 52.21-53.35%). CE or UAE at 80°C resulted in significantly higher pectin yield than those at 20°C, while the extraction time for UAE-80°C (15min) was significantly shorter compared to CE-80°C (2h) with comparable pectin yield. Moreover, MPPs extracted at 80°C were observed with higher GalA and protein content, higher Mw, resulting in higher viscosity, better emulsifying capacity and stability, as compared to those extracted at 20°C and the CP. Therefore, these results suggested that MPPs from 'Tainong No. 1' may become a highly promising pectin with good thickening and emulsifying properties, using ultrasound-assisted citric acid as an efficient and eco-friendly extraction method.