Sunflower Head Residue Pectin Extraction as Affected by Physical Conditions

Effects of extraction pH, temperature, and time on yield and quality of pectin from sunflower heads (Interstate cultivar) were investigated. The low-methoxyl pectin was extracted, using 0.75% sodium hexametaphosphate at pH 3, 4, and 5 and at 75, 85, and 95°for 20, 40, and 60 min, respectively. Yield, molecular mass, and firmness of jellies of the pectins were determined. Three-way statistical analysis on yield, molecular mass and gel firmness showed strong interactions among pH, temperature and time. Highest yields were obtained at pH 5, 95°for 20 min and pH 4, 85°for 40 min. Pectin extracted for 40 min at pH 3 and 4 and at 85°and 75°C, respectively, had the highest molecular mass. Gel firmness of sunflower pectin prepared at pH 5.4 was higher than that of a commercial citrus pectin.     

A comparison of some methods for the determination of methoxyl groups in commercial pectin preparations

The results of methoxyl groups determination in pectin preparations were compared. The methods of direct (I, II) and indirect (III, IV) methanol determination connected with enzymatic (II, IV) or alkaline (I, III) pectin demethylation were applied. Higher values were obtained using indirect methanol methods than in the case of a direct methanol determination. The difference between these groups of methods was statistically significant. The precision of all the methods was high. The degree of methylation (DM) was calculated based on methanol content; moreover in the methods III and IV it was also determined from the ratio of methylated carboxyl groups to a total of acidic groups. From the difference (%) between these two ways of calculating DM the purity of pectin can be determined. The method based on enzymatic demethylation and direct methanol analysis is recommended as a precise and selective one.     

Molecular Mass and Solubility Changes in Pectins during Storage of Satsuma Mandarin Fruits (Citrus unshiu Marc.)

Soluble pectins in satsuma mandarin fruits stored at 5°C were investigated by High Performance Gel Filtration chromatography. Pectins isolated from the flavedo, albedo, membranes and juice sacs were separated into four fractions. The hydrochloric acid soluble pectin fraction in each part was the highest and decreased slightly while the water-soluble pectin increased slightly. The avergae molecular weights of the fractionated soluble pectins in juice sacs were nearly constant but those in flavedo, albedo and membranes decreased as storage time increased. The ratios of higher molecular weight of water soluble and ammonium oxalate-soluble pectins in all the four parts and those of hydrochloric acid soluble pectin in flavedo and membranes decreased as ratios of lower molecular weight fractions increased.     

Study of albedo and carpelar membrane degradation for further application in enzymatic peeling of citrus fruits

The enzymatic activity of four commercial enzymatic preparations (Peelzym I, II, III and IV) on citrus pectin, polygalacturonic acid and carboxymethylcellulose was determined (measured as the decrease in relative viscosity). In addition, the effectiveness of these preparations in the enzymatic degradation of the albedo and the segment membrane from Cimboa fruits was assessed. The highest activity on citrus pectin was shown by Peelzym II, although Peelzym I and IV activities were also elevated, 94.5 ± 6.2% and 88.7 ± 8.3% respectively of Peelzym II activity, and no relevant differences were found between them. Peelzym II also showed the highest activity for polygalacturonic acid, which was approximately 25% more than that of Peelzym I and IV, and more than double that of Peelzym III. Peelzym IV showed 40% more EM‐cellulase activity than Peelzym I, II and III. Segment membrane solution was degraded mainly by the enzymatic preparations Peelzym I and II. Thus, the most effective activities for the degradation of the carpelar membrane from Cimboa were those activities which act mainly on pectin and especially on polygalacturonic acid. However, the albedo was degraded to the greatest extent by Peelzym II and, in turn, the most important activities for albedo degradation were those which act on polygalacturonic acid. In addition, the concentration of the enzymatic preparation for the degradation of the carpelar membrane was lower than that required for albedo degradation. Copyright © 2004 Society of Chemical Industry     

Berry Pectins: Microwave-Assisted Extraction and Rheological Properties

Press residues formed during processing of berry fruits are regarded as valuable pectin sources. In this work, pectins were extracted from press residues obtained by processing of various fresh berry fruits: red and black currant, raspberry and elderberry. The extraction was carried out by conventional and microwave-assisted methods. Comparing the two methods, the microwave-assisted process gave significantly better results. The rheological behaviour of the pectins extracted was studied, and we found that the gels of pectins from berry press residues are somewhat weaker than gel of commercial citrus pectin, but stronger than that of commercially available apple pectin. Red currant pectin was found to possess outstanding values regarding gel-forming capacity and thickening effect.     

Characterization of pectin extracted from banana peels of different varieties

Pectins were extracted from banana peels of five different varieties using citric acid solution. The chemical characteristics of banana peel pectins were investigated and compared with citrus peel and apple pomace pectins which were extracted under the same extraction conditions to assess the potential of banana peels as an alternative source of commercial pectin. The yield of banana peel pectins ranged from 15.89 to 24.08%. The extracted banana peel pectins were categorized as high methoxyl pectin with the degree of esterification between 63.15 and 72.03% comparable to those of conventional pectin sources from citrus peel (62.83%) and apple pomace (58.44%). The anhydrouronic acid (AUA) content of banana peel pectins varied from 34.56 to 66.67%. Among various banana varieties being studied, pectin from Kluai Nam Wa variety had the highest AUA content (66.67%) which met the criteria for food additive pectin indicating its commercial significance as an alternative pectin source.     

Effect of extraction conditions on the yield and purity of apple pomace pectin precipitated but not washed by alcohol

ABSTRACT:  A study of the influence of extraction conditions (pH: 1.5 to 2; temperature: 80 to 90 °C; extraction time: 1 to 3 h), on the yield and purity of apple pomace pectin without elimination of impurities by alcohol washing was carried out. The alcohol precipitate yields varied from 2.9% to 8.9% depending on the pH. At pH 1.5, these yields were higher than those obtained at pH 2 contrary to the galacturonic acid purity (%w/w). Compounds other than pectins were solubilized from the cell walls of apple pomace at pH 1.5, and they were precipitated with alcohol. The apple pectins obtained from the different extraction procedures were highly methylated (54.5% to 79.5%), especially when the conditions (temperature, pH) were drastic. Similar conclusions can be drawn for the neutral sugar content that decreased at pH 1.5 (arabinose, xylose, and galactose) or at the highest temperatures and extraction times (arabinose and galactose). The phenomenon of demethylation and pectin degradation of neutral sugars chains can be observed at acid pH, and for long extraction times. The presence of high quantities of mannose or fructose, glucose, and xylose in the alcohol precipitate showed that pectin precipitation with ethanol was not specific.     

Effect of extraction conditions on the yield and chemical properties of pectin from cocoa husks

Different extraction conditions were applied to investigate the effect of temperature, extraction time and substrate–extractant ratio on pectin extraction from cocoa husks. Pectin was extracted from cocoa husks using water, citric acid at pH 2.5 or 4.0, or hydrochloric acid at pH 2.5 or 4.0. Temperature, extraction time and substrate–extractant ratio affected the yields, uronic acid contents, degrees of methylation (DM) and degrees of acetylation (DA) of the extracted pectins using the five extractants differently. The yields and uronic acid contents of the extracted pectins ranged from 3.38–7.62% to 31.19–65.20%, respectively. The DM and DA of the extracted pectins ranged from 7.17–57.86% to 1.01–3.48%, respectively. The highest yield of pectin (7.62%) was obtained using citric acid at pH 2.5 [1:25 (w/v)] at 95 °C for 3.0 h. The highest uronic acid content (65.20%) in the pectin was obtained using water [1:25 (w/v)] at 95 °C for 3.0 h.     

Effect of debranching on the rheological properties of Ca-pectin gels

Water-soluble pectin (WSP) extract was subjected to controlled carrot pectin methylesterase treatment, thereby producing de-esterified pectin (DEP). Both WSP and DEP were incubated with a mixture of endo-arabinanase and α-L-arabinofuranosidase to yield partially debranched pectins (WSP_DBr and DEP_DBr respectively). Pectin samples were characterised in terms of degree of methylesterification (DM), neutral sugar content, and degree of branching (DBr). The characterised pectins were used for the preparation of pectin gels with high and low calcium ion (Ca²⁺) concentrations. The rheological characteristics of the produced gels were evaluated by means of small-amplitude oscillatory tests. These characteristics include network development of the gel, gel strength (G′), gel elastic character and gel type. Partial debranching of pectin resulted in a reduction of the arabinose content (by approximately 50%) and caused a slight decrease in polymer DBr. Gels produced from semi-dilute solutions of partially debranched pectins showed network development profiles similar to those prepared from semi-dilute solutions of the corresponding non-debranched polymers. Yet, the former gels showed lower G′ values, poor gel elastic character and a “weaker” nature as compared to the latter. Next to Ca²⁺ cross-links, the presence of long arabinose-containing side chains is suggested to play an important role in the rheological characteristics of Ca²⁺-pectin gels.     

Chemistry and uses of pectin — A review

Pectin is an important polysaccharide with applications in foods, Pharmaceuticals, and a number of other industries. Its importance in the food sector lies in its ability to form gel in the presence of Ca²⁺ ions or a solute at low pH. Although the exact mechanism of gel formation is not clear, significant progress has been made in this direction. Depending on the pectin, coordinate bonding with Ca²⁺ ions or hydrogen bonding and hydrophobic interactions are involved in gel formation. In low‐methoxyl pectin, gelation results from ionic linkage via calcium bridges between two carboxyl groups belonging to two different chains in close contact with each other. In high‐methoxyl pectin, the cross‐linking of pectin molecules involves a combination of hydrogen bonds and hydrophobic interactions between the molecules. A number of factors—pH, presence of other solutes, molecular size, degree of methoxylation, number and arrangement of side chains, and charge density on the molecule— influence the gelation of pectin. In the food industry, pectin is used in jams, jellies, frozen foods, and more recently in low‐calorie foods as a fat and/or sugar replacer. In the pharmaceutical industry, it is used to reduce blood cholesterol levels and gastrointestinal disorders. Other applications of pectin include use in edible films, paper substitute, foams and plasticizers, etc. In addition to pectolytic degradation, pectins are susceptible to heat degradation during processing, and the degradation is influenced by the nature of the ions and salts present in the system. Although present in the cell walls of most plants, apple pomace and orange peel are the two major sources of commercial pectin due to the poor gelling behavior of pectin from other sources. This paper briefly describes the structure, chemistry of gelation, interactions, and industrial applications of pectin.     

Pectin Concentration, Molecular Weight and Degree of Esterification: Influence on Volatile Composition and Sensory Characteristics of Strawberry Jam

Composition of headspace, consistency, taste and flavor characteristics were determined in jams made with different pectins. At usual concentrations, high methoxylated pectin induced an undesirable modification of typical flavor and intensity of flavor and taste, whereas low methoxylated pectin induced few alterations. At fixed concentration and molecular weight, a decrease in degree of esterification produced a significant decrease in consistency and noticeable modifications of the flavor perception and headspace composition, but no taste alteration. Mechanical reduction of pectin molecular weight significantly modified only the consistency.     

Structural Characteristics of Pumpkin Pectin Extracted by Microwave Heating

Abstract: To improve extraction yield of pumpkin pectin, microwave heating was adopted in this study. Using hot acid extraction, pumpkin pectin yield decreased from 5.7% to 1.0% as pH increased from pH 1.0 to 2.0. At pH 2.5, no pectin was recovered from pumpkin flesh powder. After a pretreatment at pH 1.0 and 25 °C for 1 h, pumpkin powder was microwave‐extracted at 120 °C for 3 min resulting in 10.5% of pectin yield. However, premicrowave treatment at 60 °C for 20 min did not improve extraction yield. When microwave heating at 80 °C for 10 min was applied after premicrowave treatment, final pectin yield increased to 11.3%. When pH was adjusted to 2.0, the yield dropped to 7.7% under the same extraction conditions. Molecular shape and properties as well as chemical composition of pumpkin pectin were significantly affected depending on extraction methods. Galacturonic acid content (51% to 58%) of pumpkin pectin was lower than that detected in commercial acid‐extracted citrus pectin, while higher content of neutral sugars and acetyl esters existed in pumpkin pectin structure. Molecular weight (M_w) and intrinsic viscosity (η_w) determined for microwave‐extracted pumpkin pectins were substantially lower than acid‐extracted pectin, whereas polydispersity was greater. However, microwave‐extracted pectin at pH 2.0 had more than 5 times greater M_w than did the pectin extracted at pH 1.0. The η_w of microwave‐extracted pectin produced at pH 2.0 was almost twice that of other microwave‐extracted pectins, which were comparable to that of acid‐extracted pectin. These results indicate that extraction yield of pumpkin pectin would be improved by microwave extraction and different pectin structure and properties can be obtained compared to acid extraction. Practical Application: Pumpkin is a promising alternative source for pectin material. Pumpkin pectin has a unique chemical structure and physical properties, presumably providing different functional properties compared to conventional commercial pectin sources. Depending on the conditions to produce pumpkin pectin, diverse molecular structures can be obtained and utilized in various food applications.     

响应面法优化红薯渣果胶的提取条件

果胶提取以红薯渣为原料,果胶生产常用酸盐酸作为提取用酸,在单因素试验基础上,确定料液比为1:20,对提取液pH值,提取温度T,提取时间t3个因素采用响应面方法进行了工艺优化研究。经过响应面分析了因素之间的相互影响并建立了3因素与果胶提取率的二次回归模型。结果表明:盐酸提取果胶的最优工艺参数为:温度87℃、pH1.33、时间92min,在此最优提取条件下果胶的提取率为6.24%。这为工业利用红薯渣生产果胶提供了依据。     

Gamma Radiation Effects on the Pectic Substances in Citrus Fruits

SUMMARY— Exposure of citrus fruits to gamma radiation at doses of 150 and 300 krad increased the water- and oxalate-soluble pectins and decreased the protopectin in component parts of Valencia oranges and Duncan grapefruit. The quantities of water-soluble pectin and protopectin in the peel and membrane were affected the most by irradiation. Degradation of the pectins as measured by jelly grade increased in all components of the irradiated fruits. The greatest decrease in jelly grade occurred in the March samples when the Brix/acid ratio was least. Methoxyl contents of the pectins from the peel of oranges and grapefruit decreased, while this characteristic decreased only slightly in pectins from the membrane of irradiated fruits. Pectinesterase activity in the peel of both oranges and grapefruit decreased with increased dosages, while the activity in the membrane of both fruits increased.     

Stability of bioactive compounds in fruit jam and jelly during processing and storage: A review

BackgroundFruits are the rich source of bioactive compounds (vitamins, phenolics, carotenoids, and flavonoids) attributing to the antioxidant potential. To make these fruits available for consumption during off-season, the fruits are processed into shelf-stable products like jam and jellies. However, the bioactive compounds mostly decrease during processing and storage of these products. The loss may vary with the process severity (temperature and time of processing) and product composition (sugars, pectin, fruit, etc.).Scope and approachThe overall changes in bioactive compounds during processing and storage of jam and jellies have been summarized in this review. The factors affecting these differences and the mechanisms responsible for such reactions have been discussed in detail. It might be helpful to a food scientist or a food industry in improving the product with respect to its quality and for health implications altogether.Key findings and conclusionsThe presence of high sugar content and pectin with a low degree of esterification can preserve the bioactive compounds during thermal processing by reducing the adverse reactions in jam and by interacting with functional components through hydrogen or hydrophobic bonding. The change in bioactive compounds may continue during storage depending on storage conditions, where the storage temperature and duration have a significant effect. Lower the temperature of storage, better is the retention of biologically active compounds in jam and jelly. Encapsulation and use of non-thermal processing can be explored to preserve the bioactive compounds in food products against various adverse conditions.     

High‐temperature conditioning induces chilling tolerance in mandarin fruit: a cell wall approach

BACKGROUND: High‐temperature conditioning (3 days at 37 °C and 95% relative humidity), which protects ‘Fortune’ mandarins from chilling injury (CI), manifested as pitting in the outer part of the peel (flavedo), was applied prior to cold storage (2 °C) in order to investigate the involvement of cell wall composition in the chilling tolerance of mandarins. RESULTS: Both low‐temperature storage and high‐temperature conditioning barely modified the alcohol‐insoluble substance (AIS) content or the degree of pectin esterification in the flavedo. Water‐soluble pectins (WSP) were higher in heat‐conditioned than in non‐conditioned fruits at the onset of CI. In addition, the heat‐conditioning treatment was able to increase chelator‐soluble pectins (CSP) after short cold storage periods. Covalently bound polyuronides in alkali‐soluble pectins (ASP) increased only in fruits with high incidence of CI. Cellulose and hemicellulose increased at 2 °C in both conditioned and non‐conditioned fruits, indicating that these polysaccharides may be altered by low temperature but are not related to chilling‐induced damage. CONCLUSION: High‐temperature conditioning may reduce chilling‐induced flavedo pitting in ‘Fortune’ mandarin fruit by maintaining normal levels of WSP and increasing putative sites for calcium bridge formation within the cell wall, but not by inducing changes in other matrix cell wall components. Copyright © 2012 Society of Chemical Industry     

Colour and rheological properties of non-conventional grapefruit jams: Instrumental and sensory measurement

Alternative methods with which to obtain grapefruit jams have been applied. These include the use of osmotic dehydration (OD) and/or microwave energy (MW), as an alternative to conventional heating, and the incorporation of bamboo fibre together with pectin in order to increase the jam's consistency. Colour, consistency and rheological behaviour were measured and sensory evaluation was carried out to compare product quality. When compared to the fresh fruit, the greatest colour changes took place in those jams processed by MW and conventional heating, both of them showing lower L*, a*, b* and chrome values than the rest of the samples obtained by applying osmotic dehydration. By adding bamboo fibre, the colour of OD samples approaches that of fresh fruit. The higher yield stress, greater consistency and more viscoelastic behaviour was displayed by jams obtained by combining OD and MW processes. In the sensory analysis, the judges awarded this sample a better score. The sensory attribute product coverage in mouth was closely related to viscosity at a shear rate of 120 s⁻¹ and consistency.     

Effects of high-pressure pretreatment on acid extraction of pectin from pomelo peel

To explore the effects of high-pressure processing (HPP) pretreatment on pectin extraction from pomelo albedo, the extraction yield, and characteristics of pectin were compared with those obtained via traditional acid (A-pectin) extraction. Three different pressures (300, 450, and 600 MPa) and holding times (0, 5, and 10 min) were applied to the fresh albedo, followed by acid extraction. The yield, degree of esterification (DE), galacturonic acid (GalA) content, Fourier transform-infrared (FT-IR) spectra, and rheological properties of pectin were investigated. By comparison with A-pectin, the yield increased by more than two and four times at 300 MPa at holding times of 5 and 10 min, respectively. All extracted pectins were high methoxyl pectins (DE of 76.30–87.83%) with high GalA content (62.3–86.60%); however, there were significant decreases in DE and GalA content when pressure was increased to 600 MPa in comparison with A-pectin. The pressure level and holding time significantly influenced the viscosity of pectin, and HPP-pectin 300-5, 450-10, and 600-0 exhibited a much higher viscosity than A-pectin. Consequently, this study demonstrated that HPP pretreatment of fresh albedo can increase extraction yield and/or alter pectin characteristics for further industrial applications.     

RHEOLOGICAL INDICES OF FRUIT CONTENT IN JAMS: EFFECT OF FORMULATION ON FLOW PLASTICITY OF SHEARED STRAWBERRY AND PEACH JAMS

The effect of formulation factors on Casson yield values measured at low shear rates (0.08 ≤γ≤ 1.01s^-1) (σ₀₁) and at medium shear rates (2.58 ≤γ≤ 387.30s^-1) (σ₀₂) was analyzed in previously sheared strawberry and peach jams. Twenty three samples of each fruit jam were prepared according to a second order composite rotatable design. Composition ranges were: fruit content, 25–55%; soluble solids content, 60–70° Brix; added pectin in strawberry jams, 0.3–0.7% and in peach jams, 0.1–0.5%. Variation of σ₀₁ values in strawberry jams depended mainly on the interactions between fruit and soluble solids and between fruit and pectin, while in peach jams, it depended on fruit-soluble solids and soluble solids-pectin interactions. Patterns of change of σ₀₂ values with composition were similar to those observed for σ₀₁ in both strawberry and peach jams. Predictive power of σ₀₁ and σ₀₂ values for estimation of fruit content was low, but taken in conjunction with soluble solids content and total pectin values, 79.5% of the variability of fruit content in strawberry jams and 91.1% of same in peach jams could be explained.     

RHEOLOGICAL INDICES OF FRUIT CONTENT IN JAMS: INFLUENCE OF FORMULATION ON TIME-DEPENDENT FLOW OF SHEARED STRAWBERRY AND PEACH JAMS

The influence of formulation factors [fruit content (25–55%), soluble solids content (60–70° Brix) and added pectin (0.3–0.7% in strawberry jams and 0.1–0.5% in peach jams)] on time dependent parameters has been analyzed in previously sheared jams. Twenty three samples of each fruit jam were prepared according to a second order composite rotatable design. Weltmann A values depended mainly on fruit content and on its interaction with the other two composition factors for both fruit jams. Weltmann B values, depended on the three variables and on fruit-pectin interaction for strawberry jams, while for peach jams B values depended also on fruit-soluble solids interaction.
Predictive power of time dependent parameters for estimation of fruit content was low, but considering them in conjunction with soluble solids content and total pectin values explained 91.7% of the variability of fruit content in strawberry jams and 83.7% of same in peach jams.