[Show abstract][Hide abstract] ABSTRACT: Applications of enzymes in the upgrading of fruit- and vegetable-based waste co-products are reviewed. Fruit and vegetable by-products are largely underexploited and their valorisation into functional compounds and their application in food is a promising field. Over the last years, the increasing amount of scientific research in this field shows the growing interest for renewable plant resource utilisation. Pectin-degrading enzymes as well as enzymes active towards cellulose and xyloglucans are described and their potential and current uses are explained and the uses of the final products are documented. Non-scientific aspects such as the economics, legislation, and the consumer point of view are also discussed.
[Show abstract][Hide abstract] ABSTRACT: Pectins are extremely complex polysaccharides that can be viewed as multiblock co-biopolymers. Although the fine structure of the different pectic blocks is now quite well known, the way in which they are combined into a macromolecular structure is still a matter of debate. Large differences in pectins quality and quantity exist between different cell types, at different stages of cellular development and even within the thickness of a given wall. A way to understand how the different structural elements are connected to one another to form variable macromolecular structures is to isolate and identify the different connection points. Another, and complementary, way is to specifically isolate the different pectic domains in order to study their hydrodynamic properties. Six monocotyledonous and dicotyledonous species were selected and pectins were extracted from cell wall materials using a four-step sequential extraction scheme. The isolation and characterization of pectin structural elements showed that structural discrepancies of pectins differing in HG/RG-I balance could be due to a variable amount of HG domains decorating an RG-I backbone. Our results also support the hypothesis of a hyper-variability of RG-I backbone length. However, the structural complexity and heterogeneity of pectins make it very difficult to appraise the relationship between pectin fine structure and hydrodynamic properties, especially when the compared pectins are derived from different plant species and obtained with different extractants. The Arabidopsis pectin mutant quasimodo2 was thereby studied. By specifically isolating HG blocks, qua2 appeared to be specifically deficient in HG, with no change in the amount of RG-I blocks. Moreover, the remaining HGs had maintained the same size as those in the wild type. The possible macromolecular build up of pectins is discussed in the light of the presented results.
[Show abstract][Hide abstract] ABSTRACT: An acetylesterase was purified from Aspergillus aculeatus on the basis of its ability to deacetylate homogalacturonan. A series of well-characterized substrates was prepared and used to investigate its specificity, including pectin with various degrees of methylation and acetylation, pectic domains with various structures, and oligomers. It was then compared to a rhamnogalacturonan acetylesterase previously isolated from the same fungus. Both enzymes were active towards various acetylated pectins, and were able to release acetyl groups from acetylated homogalacturonan, oligogalacturonates as well as rhamnogalacturonan at different extent. It was thus concluded that while the two enzymes differed in their efficiency, they are both pectin acetylesterases, able to act in the “smooth” as well as in the “hairy” regions of pectin.
Full-text · Article · Nov 2008 · Carbohydrate Polymers
[Show abstract][Hide abstract] ABSTRACT: The extraction of pectins from mango peels can offer a way to upgrade byproducts arising from the processing of these tropical fruits. In this work, several extraction conditions (HCl, or deionised water, or ammonium oxalate) were tested in order to isolate pectins from the peels of two mango varieties (Améliorée and Mango) harvested in Cameroon. After determining uronic acid and neutral sugar contents of mango peels and their alcohol insoluble residues (AIR), extracted pectins were analysed for their uronic acid and neutral sugar contents, their degree of methylation and acetylation, and their average molar mass and intrinsic viscosity. The extraction method was shown to significantly act upon yield (9–32% dry AIR), uronic acid (262–709 mg/g dry weight) and neutral sugar (160–480 mg/g) contents of pectin, their degree of methylation (52–86%) and acetylation (1–8%), their molar mass (245,000–432,000 g/mol), and their intrinsic viscosity (320–1346 mL/g). The physicochemical behaviour of pectins could be influenced thereof. With a good recovery yield, a high average molar mass and intrinsic viscosity and a high degree of methylation, ammonium oxalate-extracted mango pectins present good characteristics to be exploited industrially for their gelling properties.
Full-text · Article · Oct 2008 · Food Hydrocolloids
[Show abstract][Hide abstract] ABSTRACT: Extraction and use of pectins from ambarella peels could add value to the waste products arising from processing of the fruit. Dried alcohol-insoluble residues (AIR) of ambarella peels were treated separately with HCl, deionised water and oxalic acid/ammonium oxalate solutions, and the resulting pectin extracts analysed for some biochemical and physicochemical parameters. The results show that pectin yield (9–30% dry AIR), uronic acid (557–727 mg/g dry weight), neutral sugars (125–158 mg/g), degree of methylation (50–58%) and acetylation (4–6%), molar mass (263,000–303,000 g/mol) and intrinsic viscosity (179–480 ml/g) varied significantly (p < 0.05) with the various extraction methods used. Extraction with oxalic acid/ammonium oxalate solution gave the highest pectin yield, with high molar mass and degree of methylation, making the extracts suitable for use as additives in the food industry. The results compared well to lime pectin extracted under the same conditions, indicating their commercial significance.
[Show abstract][Hide abstract] ABSTRACT: The objective of the present work was to relate the physical evolution quantified by image analysis to the chemical transformation of beet pulp particles during enzymatic degradation. Beet pulps were degraded into a torus reactor equipped for visualisation. Pectinolytic and cellulolytic enzymes were used separately or in combination. Two global image analysis techniques were tested to characterise the size distribution of overlapping particles. Granulometric curves were extracted by mathematical morphology and a regularisation dimension was assessed by fractal analysis. Both techniques proved efficient to follow particle size evolution during degradation. When using cellulolytic enzymes alone, no chemical or physical evolution was observed. When using pectinolytic enzymes, a chemical modification occurred without any physical evolution. Particles physically disappeared when both enzymes were used. The chemical and physical evolutions of particles during degradation were interpreted taking into account the current model of molecular arrangement of primary cell walls.
Full-text · Article · Dec 2006 · Journal of Food Engineering
[Show abstract][Hide abstract] ABSTRACT: The pectin content, composition and physico-chemical properties were studied in the fruits of two genotypes of Japanese quince. On average, the fruits contained 11 g pectins/100 g dry fruit and 1.4 g pectins/100 g fresh fruit. A sequential extraction was used to isolate the pectins from the fruits. The cells from the flesh were examined using a confocal laser scan microscope, fresh and after each extraction step of the sequence. The dilute acid conditions were the most efficient for pectin extraction. Pectins extracted by water or potassium oxalate had higher (>600 ml/g) intrinsic viscosities than the pectins extracted by dilute acid (
No preview · Article · Sep 2003 · Carbohydrate Polymers
[Show abstract][Hide abstract] ABSTRACT: Endopolygalacturonase from Fusarium moniliforme was used to degrade acetylated homogalacturonan previously prepared from sugar beet pulp. The initial velocity and the final percentage of hydrolysis decreased very rapidly with increasing degree of acetylation, showing that acetyl substitution markedly affected the enzymatic activity. MALDI-TOF mass spectrometry was used to analyse the reaction products and to show acetyl groups on the oligogalacturonates. The results demonstrated that the enzyme was able to accommodate acetyl groups in its active site cleft. The influence of acetyl groups on the mode of action of the enzyme was discussed and compared to the influence of methyl groups.
Full-text · Article · Jun 2003 · Carbohydrate Polymers
[Show abstract][Hide abstract] ABSTRACT: Pectins are present as structural polysaccharides in the middle lamella and the primary cell-walls of higher plants. They are part of our diet either as additives in some food products or as constituants of the raw materials used in the food products. Their physico-chemical properties, within the cell wall matrix or after extraction, are of prime importance both from a functional and a nutritional point of view.
Industrial pectins are extracted from by-products of the fruit juice industry (apple pomace or citrus peels). They are extracted in acidic conditions and chemically modified to give High Methoxy (HM) pectins and Low Methoxy (LM) pectins (some may be also amidated). The properties of these two main types of differ widely. The HM pectins form gels in acidic conditions and in presence of sugars whereas the LM pectins needs calcium for gelation. The gelation mechanisms are directly linked to the conformation of the molecules, to their polyelectrolyte nature, and to the amount and distribution of the substituents (methyl, amid ...). The characteristics of the surrounding solutions (pH, ionic strength, nature of the ions, presence of cosolutes, temperature..) may also play key roles. The application areas of these gels are mainly in the food industries: jams, marmelades, jellies, confectionery...Their stabilizing properties are now more and more used, for instance in acid milk products.
Within the cell wall, the pectins may have another range of important properties in relation to ion-binding and to hydration which depend on numerous parameters. Furthermore, the physical structure of the matrix is also very important and particle size, surface area, porosity have to be considered in the dietary fibre context.
[Show abstract][Hide abstract] ABSTRACT: An improved hplc method for the simultaneous determination of the degrees of methylation and acetylation of pectins has been developed. The proposed method involves saponification in heterogeneous medium followed by the separation of methanol, acetic acid and internal standard on a C18 column and quantification by refractometry. The method is reproducible, accurate, and presents several advantages that are discussed in the present paper.
Full-text · Article · Nov 2002 · Food Hydrocolloids
[Show abstract][Hide abstract] ABSTRACT: A combined enzymatic and HPLC method was validated for analysis of galacturonic acid (GalA) in (1) alcohol-insoluble solids (AIS), and in (2) pectins, extracted from fruits of Japanese quince (Chaenomeles japonica), by comparison with a standard colorimetric method (using metahydroxydiphenyl) for analysis of uronic acids (UA). For analysis of AIS, the results of the colorimetric and the enzymatic/HPLC methods were identical (UA and GalA in average 20 g/100 g AIS dry weight). For analysis of pectins, the colorimetric method resulted in consistently higher estimates (UA in average 63 g/100 g pectins dry weight) compared to the enzymatic/HPLC method (GalA in average 57 g/100 g pectins dry weight). The enzymatic/HPLC method also proved to be useful as a simple and efficient screening method, since a very high Pearson correlation (R=0.93) was obtained between GalA estimates of the homogenized fruit sample and the AIS content of acid-extracted pectins.
No preview · Article · Sep 2002 · Lebensmittel-Wissenschaft und-Technologie
[Show abstract][Hide abstract] ABSTRACT: The study of the cell-wall polysaccharides of the fruits of Japanese quince (Chaenomeles japonica) was achieved in two stages: (i) preparation of alcohol insoluble solids (AIS) from the different tissue zones and entire fruits of two genotypes and (ii) treatment of the AIS with extractants. The AIS represented an average of 32 g/100 g entire dry fruit and 4 g/100 g entire fresh fruit. A sequential extraction scheme allowed the separation of the cell-wall material into its major components (cellulose, pectins and hemicelluloses). The AIS was composed of 30 g pectins/100 g AIS, 8 g hemicelluloses/100 g AIS and 60 g cellulosic residue/100 g AIS. 100 g entire dry fruit (800 g entire fresh fruit) contained 11 g pectins, 3 g hemicelluloses and 18 g cellulosic residue. Pectins were mostly located in the flesh of the fruit, they were more efficiently extracted with hot dilute acid than with other extraction media and they had a high degree of methylation (DM) and a low degree of acetylation (DAc). Sequential extraction allows a first fractionation of the pectins. Hot dilute acid extracted pectins substituted with long Ara side-chains, whereas cold dilute alkali extracted pectins with more numerous but shorter side-chains. No difference was pointed out neither in the quantity of polysaccharides extracted from the two genotypes studied nor in the composition of these constitutive polysaccharides.
No preview · Article · Aug 2002 · Carbohydrate Polymers