Structural and Emulsifying Properties of Citric Acid Extracted Satsuma Mandarin Peel Pectin

Comparison of structures and emulsifying properties between water-extracted pectins from Fructus aurantii

The structural characteristics of two water-extracted pectic polysaccharides from Fructus aurantii were investigated, and the impacts of their structures on the emulsifying stability were evaluated. FWP-60 (extracted by cold water and followed 60 % ethanol precipitation) and FHWP-50 (extracted by hot water and followed 50 % ethanol precipitation) were both high methyl-esterified pectins, which were composed of homogalacturonan (HG) and highly branched rhamnogalacturonan I (RG-I) regions. The weight-average molecular weight, methyl-esterification degree (DM) and HG/RG-I ratio of FWP-60 were 1200 kDa, 66.39 % and 4.45, respectively, which were 781 kDa, 79.10 % and 1.95 for FHWP-50. The methylation and NMR analysis of FWP-60 and FHWP-50 demonstrated that the main backbone consisted of different molar ratios of →4)-α-GalpA-(1 → and →4)-α-GalpA-6-O-methyl-(1→, and the side chains contained arabinan and galactan. Moreover, the emulsifying properties of FWP-60 and FHWP-50 were discussed. Compared with FHWP-50, FWP-60 had better emulsion stability. Overall, pectin had a linear HG domain and a small number of RG-I domain with short side chains to facilitate the stabilization of emulsions in Fructus aurantii. A comprehensive knowledge of the structure characteristic and emulsifying property would enable us to provide more information and theoretical guidance for the structure and emulsion preparation of Fructus aurantii pectic polysaccharides.

Emulsifying properties, in vitro digestive characteristics, and β-carotene bioaccessibility of mandarin peel pectin emulsions prepared with different carrier oil phases

Mandarin peel pectin (MPP) emulsions were prepared with different oil phase loadings with or without β-carotene, and their emulsifying characteristics, digestive properties and β-carotene bioaccessibility were investigated. Results revealed that all MPP emulsions exhibited good loading efficiency for β-carotene, while their apparent viscosity and interfacial pressure (π) of MPP emulsions increased significantly after the addition of β-carotene. Emulsification of MPP emulsions as well as digestibility were significantly dependent on the kind of oil. MPP emulsions prepared with long-chain triglycerides (LCT) oil (soybean, corn, and olive oil) exhibited higher volume average particle size (D_4,3), apparent viscosity, π values, and bioaccessibility of carotene compared to those prepared with medium-chain oils (MCT). MPP emulsions with LCT rich in monosaturated fatty acids (olive oil) had the highest β-carotene encapsulation efficiency, bioaccessibility, etc. than from other oils. This study provides a theoretical basis for the efficient encapsulation and high bioaccessibility of carotenoids with pectin emulsions.

Jabuticaba (Plinia sp.) Peel as a Source of Pectin: Characterization and Effect of Different Extraction Methods

The peel of jabuticaba, a small fruit native to Brazil, has been shown to be a potential source of antioxidants and soluble dietary fibers. In this study, flours prepared from these peels were evaluated as a source of pectin. Different extraction methods were employed: ultrasound (US) extraction followed by low temperature heating (40 °C); in a microwave (MW) without (method 1) or with cellulase (method 2) or hemicellulase (method 3); or in a water bath (method 4). Pectin yields ranged from approximately 18% for methods 1 and 4 up to 22% for enzyme-assisted extractions (methods 2 and 3). Methods that did not employ enzymes resulted in low amounts of methoxyl pectins, as opposed to high amounts of methoxyl pectins obtained after enzyme treatment. Cyanidin-3-O-glucoside (C3G) and ellagic acid were the main phenolic compounds found in jabuticaba peel pectins, with higher C3G levels obtained with enzyme-free extraction (methods 1 and 4). All pectins from jabuticaba peel presented a reddish tone, good emulsifying properties and high swelling capacity. The pectin extracted using US+MW+cellulase (method 2) presented better emulsifying performance (higher values of emulsifying activity and emulsion stability), more effective than commercially available citrus pectin.

Characterization of Physicochemical Properties of Oil-in-Water Emulsions Stabilized by Tremella fuciformis Polysaccharides

In this paper, emulsions stabilized by Tremella fuciformis polysaccharides (TFP) were prepared and the physiochemical properties were assessed. Results showed that the TFP emulsions illustrated the highest emulsifying activity (EAI) and emulsifying stability (ESI) when the concentration of TFP and oil were 0.8% and 10% (wt%). The higher pH value was in favor of the emulsifying properties, while the addition of NaCl impaired the stability, and the greater the concentration, the lower the EAI and ESI. Besides, the emulsifying and rheological properties and stability analysis were evaluated in comparison with gum arabic, pectin, and carboxymethyl cellulose emulsions. It was discovered that TFP illustrated better storage and freeze-thaw stability, which was proved by the result of zeta-potential and particle size. The rheological measurement revealed that all the emulsions behaved as pseudoplastic fluids, while TFP displayed a higher viscosity. Meanwhile, TFP emulsions tended to form a more stable network structure according to the analysis of the parameters obtained from the Herschel–Bulkley model. FTIR spectra suggested that the O-H bond could be destructed without the formation of new covalent bonds during the emulsion preparation. Therefore, this study would be of great importance for the research of emulsions stabilized by TFP as a natural food emulsifier.

Extraction of Pectin from Satsuma Mandarin Peel: A Comparison of High Hydrostatic Pressure and Conventional Extractions in Different Acids

Satsuma mandarin peel pectin was extracted by high hydrostatic pressure-assisted citric acid (HHPCP) or hydrochloric acid (HHPHP), and the physiochemical, structural, rheological and emulsifying characteristics were compared to those from conventional citric acid (CCP) and hydrochloric acid (CHP). Results showed that HHP and citric acid could both increase the pectin yield, and HHPCP had the highest yield (18.99%). Structural characterization, including NMR and FTIR, demonstrated that HHPHP showed higher Mw than the other pectins. The viscosity of the pectin treated with HHP was higher than that obtained with the conventional method, with HHPHP exhibiting significantly higher viscosity. Interestingly, all the pectin emulsions showed small particle mean diameters (D_4,3 being 0.2–1.3 μm) and extremely good emulsifying stability with centrifugation and 30-day storage assays, all being 100%. Satsuma mandarin peel could become a highly promising pectin source with good emulsifying properties, and HHP-assisted acid could be a more efficient method for pectin extraction.

Enzymatic Hydrolysis Modifies Emulsifying Properties of Okra Pectin

Okra pectins (OKPs) with diverse structures obtained by different extraction protocols have been used to study the relationship between their molecular structure and emulsifying properties. A targeted modification of molecular structure offers a more rigorous method for investigating the emulsifying properties of pectins. In this study, three glycoside hydrolases, polygalacturonase (PG), galactanase (GL), and arabinanase (AR), and their combinations, were used to modify the backbone and side-chains of OKP, and the relationships between the pectin structure and emulsion characteristics were examined by multivariate analysis. Enzymatic treatment significantly changed the molecular structure of OKP, as indicated by monosaccharide composition, molecular weight, and structure analysis. GL- and AR- treatments reduced side-chains, while PG-treatment increased side-chain compositions in pectin structure. We compared the performance of hydrolyzed pectins in stabilizing emulsions containing 50% v/v oil-phase and 0.25% w/v pectin. While the emulsions were stabilized by PG (93.3% stability), the emulsion stability was reduced in GL (62.5%), PG+GL+AR (37.0%), and GL+AR (34.0%) after 15-day storage. Furthermore, microscopic observation of the droplets revealed that emulsion destabilization was caused by flocculation and coalescence. Principal component analysis confirmed that neutral sugar side-chains are key for long-term emulsion stabilization and that their structure explains the emulsifying properties of OKP. Our data provide structure-function information applicable to the tailored extraction of OKP with good emulsification performance, which can be used as a natural emulsifier.

High Internal Phase Emulsions Preparation Using Citrus By-Products as Stabilizers

The citrus juice industry produces about 50% of by-products. Citrus pomace (CP) contains many polysaccharides (mainly cellulose and pectin), which could act as stabilizers and emulsifiers. The aim of this work was to obtain high internal phase emulsions (HIPEs) using unmodified CP at different concentrations to valorize citrus by-products. The synergic effect of pea protein isolate (PPI) with CP to stabilize the HIPEs was also studied. HIPEs structure was analyzed using rheological and microscopy studies as well as color and physical stability of the emulsions. According to rheological data, all samples exhibited a solid-like behavior, as elastic modulus (G’) was higher than viscous modulus (G’’) within the viscoelastic linear region; as % CP and % PPI increased, greater values of G’ and apparent viscosity (η) were achieved. Microscopic images showed that oil droplets had a polyhedral shape and were enclosed by a thin layer of CP and PPI. Increasing concentrations of CP and PPI enhanced oil droplets packaging. Emulsions’ physical stability was better when adding PPI. The results showed that stable HIPEs with 1.25% of CP and PPI over 0.5% can be obtained. These HIPEs could be used to formulate emulsions for food applications, such as mayonnaises, fillings, or creams.