Optimisation of freeze drying conditions for purified serine protease from mango (Mangifera indicaCv. Chokanan) peel

This study investigated the possible relationship between the encapsulation variables, namely serine protease content (9–50 mg/ml, X₁), Arabic gum (0.2–10% (w/w), X₂), maltodextrin (2–5% (w/w), X₃) and calcium chloride (1.3–5.5% (w/w), X₄) on the enzymatic properties of encapsulated serine protease. The study demonstrated that Arabic gum, maltodextrin and calcium chloride, as coating agents, protected serine protease from activity loss during freeze-drying. The overall optimum region resulted in a suitable freeze drying condition with a yield of 92% for the encapsulated serine protease, were obtained using 29.5 mg/ml serine protease content, 5.1% (w/w) Arabic gum, 3.5% (w/w) maltodextrin and 3.4% (w/w) calcium chloride. It was found that the interaction effect of Arabic gum and calcium chloride improved the serine protease activity, and Arabic gum was the most effective amongst the examined coating agents. Thus, Arabic gum should be considered as potential protection in freeze drying of serine protease.     

Response surface methodology and multivariate analysis of equilibrium headspace concentration of orange beverage emulsion as function of emulsion composition and structure

The influence of emulsion composition (i.e. Arabic gum, xanthan gum and, orange oil) and structural emulsion properties (i.e. average droplet size and apparent viscosity) on equilibrium headspace concentration of beverage emulsions was investigated. Increase in average droplet size led to increase the equilibrium headspace concentration of more hydrophilic volatile compounds (i.e. lower log P) such as ethyl acetate and octanal, but decrease in more hydrophobic volatile compounds such as 3-carene, myrcene and limonene. In most cases, apparent viscosity had significant positive effect on equilibrium headspace concentration. Principle component analysis (PCA) score discriminated the beverage emulsions containing the same orange oil content but different contents of emulsifiers in different classes, thus indicating the significant (p < 0.05) effect of emulsifier fraction on equilibrium headspace concentration. Beverage emulsion containing 22.2% (w/w) Arabic gum, 0.52% (w/w) xanthan gum and 14.21% (w/w) orange oil was estimated to provide the highest equilibrium headspace concentration.     

Effect of Arabic gum,xanthan gum and orange oil on flavor release from diluted orange beverage emulsion

The influence of main emulsion components namely Arabic gum (13–20% w/w), xanthan gum (0.3–0.20% w/w) and orange oil (10–14% w/w) on semi-quantitative headspace analysis of target volatile flavor compounds released from a model orange beverage (diluted orange beverage emulsion) was evaluated by using a three-factor circumscribed central composite design (CCCD). For optimization procedure, the peak area of 13 volatile flavor compounds (i.e. ethyl acetate, α-pinene, ethyl butyrate, β-pinene, 3-carene, myrcene, limonene, γ-terpinene, octanal, decanal, linalool, neral and geranial) were considered as response variables. The response surface analysis exhibited that the significant (p < 0.05) second-order polynomial regression equations were successfully fitted for all response variables except for ethyl butyrate. A satisfactory coefficient of determination (R²) ranged from 0.831 to 0.969 (>0.8) was obtained for the response variables studied. No significant (p > 0.05) lack of fit was indicated for the reduced models except for the models fitted for limonene and linalool. This observation confirmed an accurate fitness of the reduced response surface models to the experimental data. The multiple response optimizations indicated that an orange beverage emulsion containing 15.87% (w/w) Arabic gum, 0.5% (w/w) xanthan gum and 10% (w/w) orange oil was predicted to provide the minimum overall flavor release.     

Response surface modeling for optimization of formulation variables and physical stability assessment of walnut oil-in-water beverage emulsions

The effect of Arabic gum content (5-10% w/w) and walnut-oil concentration (3-6% w/w) on properties of prepared walnut oil/water emulsion, including turbidity loss rate, density, size index, particle size and stability, was investigated using response surface methodology (RSM). For each response, a second-order polynomial model with high coefficient of determination (R²) values ranging from 0.907 to 0.989 was developed using multiple linear regression analysis. The lack of significant difference between the experimental and predicted values proved the adequacy of response surface equations for describing the physical changes of emulsions. An increase of Arabic gum content in range and initial concentration of walnut oil were associated with high emulsion stability and minimum droplet size. It can be concluded that RSM can determine the most suitable formulation (3% w/w walnut oil and 9.62% w/w Arabic gum) to achieve the highest stability in a developed beverage emulsion based on walnut oil.     

Surface tension and refractive index of guar and tragacanth gums aqueous dispersions at different polymer concentrations,polymer ratios and temperatures

Surface tension and refractive index of guar gum (GG) (up to 0.97% w/w) and tragacanth gum (TG) (up to 1.41% w/w) aqueous dispersions were determined for systems with only one and both gums (mixtures) (up to 1.25% w/w). Experimental determinations were carried out from 5 to 30 °C for surface tension and from 10 °C to 40 °C for refractive index. For mixtures, the effect of polymer ratio (1:3, 1:1 and 3:1) was analyzed at different total gum concentration and temperature. GG showed lower surface activity and refractive index than TG at the same experimental condition. Models for the estimation of surface tension and refractive index as function of gum concentration and temperature were proposed and satisfactorily tested. Both physical and optical properties, in the tested gum concentration range, allowed the determination of different behaviour for both gums because of a critical aggregation concentration for TG dispersions while this phenomenon was not observed for GG.     

Optimisation of aqueous extraction of gum from durian (Durio zibethinus) seed: A potential, low cost source of hydrocolloid

The main goal of the present study was to investigate the effect of aqueous extraction conditions on the extraction yield and physicochemical properties of the durian seed gum. The studied aqueous extraction variables were water/seed (W/S) ratio (20:1-60:1, w/w), temperature (25.0-85.0 °C), and pH (4.0-10.0). The results indicated that the aqueous extraction variables exhibited the least significant (p < 0.05) effect on oil-holding capacity (OHC). Conversely, they had the most significant (p < 0.05) effect on the span and extraction yield. The current study revealed that the interaction effect of aqueous extraction variables showed the least significant (p < 0.05) effect on the solubility and OHC of durian seed gum. The optimum extraction condition led to the production of durian seed gum with a relatively high extraction yield (56.4%), solubility (27.9%), volume-weighted mean (98.7 μm), span (3.8), water-holding capacity (WHC) (270.6 g water/100 g gum), and OHC (146.5 g oil/100 g gum).     

Rheological behavior and stability of d-limonene emulsions made by a novel hydrocolloid (Angum gum) compared with Arabic gum

Our goal was to evaluate emulsion stability, droplet size analysis and rheological behavior of the emulsions prepared by a native biopolymer namely Angum gum (An) compared with Arabic gum (Ar) stabilized emulsions. After gum extraction, gum dispersions with maltodextrin were prepared in water (in 1-5% concentrations) and emulsified with 5% and 10% d-limonene using high pressure homogenization. Statistical analysis revealed a significant influence of gum type and gum concentration on emulsion stability at α = 0.05. Flavor level was not important statistically in emulsion stability but it was the only factor with a significant influence (P < 0.05) on surface tension of the emulsions. The results showed that Angum gum was superior to Arabic gum in stabilizing emulsions during storage. Also, rheological data revealed that Angum gum-emulsions’ behavior was following the Herschel-Bulkley model with higher viscosities compared to Arabic gum emulsions, which could be the main reason of higher emulsion stabilities with this novel hydrocolloid.     

Improvement of the stability of nattokinase using γ-polyglutamic acid as a coating material for microencapsulation

In this study, nattokinase (NK) was microencapsulated in high-molecular-weight Na-γ-PGA, and the amount of NK added to the Na-γ-PGA was in the ratio of 1:1 and 2:1 w/w, which was designated as NK-100 and NK-200, respectively. The temperature and pH stability of microencapsulated NK were found to be higher than those of the free form. Free NK lost its overall initial activity after treatment at a temperature above 60 °C or at a pH less than 5.0 for 1 h. NK-100 and NK-200 retained 35% and 60% of their activities after exposure to an acidic condition of pH 4.0 and possessed 18% and 25% activity after treatment at 60 °C for 1 h, respectively. Furthermore, NK-100 and NK-200 exhibited more protective bioactivity than free NK did in storage stability tests. This simple and versatile approach can be potentially applied to the microencapsulation of various biomolecules for drug-delivery applications.     

Thermal and rheological properties of tapioca starch gels with and without xanthan gum under cold storage

Changes in the thermal and rheological properties of tapioca starch (TS) with and without xanthan gum (Xan) (total polysaccharide concentration = 25% w/w) were investigated using a differential scanning calorimeter, Rheolograph Gel and Texture Analyser. The gelatinization temperatures of TS shifted to higher values with the Xan concentration. Xan enhanced the retrogradation of TS during the initial stage of storage but retarded the process for a further storage time at 5 °C. The onset temperature of all reheated TS/Xan gels decreased with increasing storage time indicating thermally unstable structure formation after a longer storage time. Storage Young’s moduli (E′) of the TS and TS/Xan gels stored at 5 °C increased with increasing storage time. The E′ values became more temperature dependent with storage time due to the weak cross-linkage of amylopectin molecules in the gels but became less dependent in the system containing Xan. TS/Xan gels kept for 14 days showed lower Young’s moduli than TS gels from the compression test confirming retardation of the retrogradation process by Xan. The results suggested that Xan could retard the retrogradation of TS gels for longer storage times.     

Influence of sucrose on thermal and pasting properties of tapioca starch and xanthan gum mixtures

Sugars and hydrocolloids are used in starch-based product formulations during processing for improving the final quality of foods. Effect of sucrose (0–30%) on thermal and pasting properties of 5% w/w tapioca starch (TS) – xanthan gum (Xan) mixtures was investigated using differential scanning calorimeter (DSC), rapid visco-analyser (RVA) and rheometer. Sucrose increased gelatinization temperatures and enthalpies of TS and TS/Xan dispersions. RVA pasting temperatures, peak viscosity, final viscosity, breakdown and setback values of TS/Xan mixtures increased with increasing sucrose concentration (p < 0.05). Addition of sucrose in all TS/Xan pastes increased the rate of viscosity breakdown during RVA heating under constant shear and temperature. Setback values of TS/Xan pastes increased with sucrose addition but decreased significantly with increasing Xan content. Xan enhanced thermal stability of steady shear viscosities to TS pastes with and without sucrose. Linear regression from pasting profile revealed a good relationship for predicting final viscosity. These results could facilitate the development of TS-based products with improved thermal and pasting properties.     

The influence of the carrier addition and spray drying temperatures on physicochemical properties of microencapsulated carrot juice powder

The objective of this study was to determinate the influence of carrier addition and spray drying temperatures (160 or 200°C) on physicochemical properties of spray-dried carrot juice powder. As carriers, maltodextrin and gum Arabic in different proportions were used. In powders were determined the following: moisture content, water activity, apparent density, size of particles, colour and carotenoids content. The content of carotenoids in powders prepared from solutions with juice to carrier ratio 2:3 was 324.3–406.6 mg/kg d.m., while in powders with a J:C = 3:2 values ranged from 576.7 to 637.7 mg/kg d.m. The highest content of carotenoids and the most yellow colour were observed in powders with 1:3 gum Arabic to maltodextrin ratio. Powders with the highest amount of gum Arabic have the highest diameter and the lowest water activity. High inlet temperature caused brighter colour of powders, higher dry matter content, lower water activity and apparent density of powders.     

Thermal inactivation kinetics of Rabdosia serra (Maxim.) Hara leaf peroxidase and polyphenol oxidase and comparative evaluation of drying methods on leaf phenolic profile and bioactivities

Inactivation kinetics of peroxidase and polyphenol oxidase in fresh Rabdosia serra leaf were determined by hot water and steam blanching. Activation energy (52.30 kJ mol⁻¹) of polyphenol oxidase inactivation was higher than that (20.15 kJ mol⁻¹) of peroxidase. Water blanching at 90 °C or steam blanching at 100 °C for 90 s was recommended as the preliminary treatment for the retention of phenolics. Moreover, comparative evaluation of drying methods on the phenolics profiles and bioactivities of R. serra leaf were conducted. The results indicated that only intact leaf after freeze drying retained the initial quality. The sun- and air-dried leaves possessed identical phenolic profiles. The homogenised leaf (after freeze-drying) possessed a lower level of phenolics due to enzymatic degradation. Good antioxidant activities were detected for the sun- and air-dried leaves. There was insignificant difference in anti-tyrosinase and anti-α-glucosidase activities among sun-, air-, and freeze-dried leaves.     

Emulsifying Properties of Angum Gum (Amygdalus scoparia Spach) Conjugated to β-Lactoglobulin through Maillard-Type Reaction

In this study, emulsifying properties of Angum gum were improved by covalent bonding with β-lactoglobulin (BLG). Angum gum is a natural gum exudate from mountain almond trees (Amygdalus scoparia Spach). Covalent linkage of β-lactoglobulin-Angum gum conjugate was confirmed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Emulsifying properties of emulsions containing β-lactoglobulin:Angum gum (1:1) conjugates were studied with the advancement of Maillard reaction. Dry-heating time showed no significant (p > 0.05) effect on the emulsion activity index; however, emulsion stability index were significantly increased over time and emulsion stability index of two weeks incubated β-lactoglobulin-Angum gum conjugate was significantly different (p < 0.05) from others (β-lactoglobulin-Angum gum mixture, 0, 2, 6 days, and 2 weeks). Moreover, the creaming index decreased with advancement of Maillard-type conjugation of β-lactoglobulin:Angum gum (1:1). β-lactoglobulin-Angum gum conjugates (1:1, 1:2, and 2:1) exhibited much better emulsification performance than Angum gum and gum Arabic alone at the same emulsifier/oil ratio (1.5 wt. % total biopolymer/ 40% v/v oil). In addition, assessing droplet size distribution during storage and freeze-thaw treatment revealed that β-lactoglobulin:Angum gum (1:1) conjugate had finer droplet size compared to other β-lactoglobulin/Angum gum mixing ratios (1:2 and 2:1), Angum gum and gum Arabic.     

Physical properties of a composite film containing sunflower seed meal protein and its application in packaging smoked duck meat

Sunflower seed meal protein (SP) films were prepared using various plasticizers, cross-linking agents, Cloisite Na⁺ or red algae, and their physical properties, such as tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) were determined. The TS, E, and WVP of the SP film containing sucrose and fructose (2:1) as a plasticizer and cinnamaldehyde as a cross-linking agent were 3.05 MPa, 34.42%, and 2.25 × 10⁻⁹ g m/m² s Pa, respectively. The incorporation of Cloisite Na⁺ improved the physical properties of the SP film. The TS of the SP/Cloisite Na⁺ composite film containing 3% Cloisite Na⁺ increased by 2.19 MPa, and the WVP of the composite film decreased by 0.52 × 10⁻⁹ g m/m² s Pa compared to the SP film. The incorporation of red algae also improved the TS of the SP film. The TS of the SP composite film containing 1.2% red algae increased by 3.82 MPa compared to the SP film. In addition, an SP/red algae composite film containing grapefruit seed extract (GSE) was prepared and used in food packaging. After 12 days of storage, the population of Listeria monocytogenes inoculated on smoked duck meats packed with the SP/red algae composite film containing 1.2% GSE decreased by 1.31 log CFU/g compared to the control packaging. Therefore, these results suggest that SP composite films can be prepared by the addition of red algae to the SP film–forming solution and that the SP/red algae composite film containing GSE can be used as an antimicrobial food packaging material.     

Feasibility study for producing a carrot/potato matrix reference material for 11 selected pesticides at EU MRL level: Material processing, homogeneity and stability assessment

The feasibility for producing a matrix reference material for selected pesticides in a carrot/potato matrix was investigated. A commercially available baby food (carrot/potato-based mash) was spiked with 11 pesticides at the respective EU maximum residue limits (MRLs), and further processed by either freezing or freeze-drying. Batches of some 150 units were produced per material type. First, the materials were assessed for the relative amount of pesticide recovered after processing (ratio of pesticide concentration in the processed material to the initially spiked pesticide concentration). In addition, the materials’ homogeneity (bottle-to-bottle variation), and the short-term (1 month) and mid-term (5 months) stability at different temperatures were assessed. For this, an in-house validated GC-EI-MS method operated in the SIM mode with a sample preparation procedure based on the QuEChERS (“quick, easy, cheap, effective, rugged, and safe”) principle was applied. Measurements on the frozen material provided the most promising results (smallest analyte losses during production), and also freeze-drying proved to be a suitable alternative processing technique for most of the investigated pesticides. Both the frozen and the freeze-dried material showed to be sufficiently homogeneous for the intended use, and storage at −20 °C for 5 months did not reveal any detectable material degradation. The results constitute an important step towards the development of a pesticide matrix reference material.     

Fractionation of citronella (Cymbopogon winterianus) essential oil and concentrated orange oil phase by batch vacuum distillation

The aim of this work was to assess the performance of a vacuum fractionating column for the fractionation of citronella essential oil and concentrated orange oil phase during batch mode operation at different pressures, from 20 to 1 mbar and reflux ratios from 1:1 to 10:1. Fractions from column top and bottom were analyzed by gas chromatography (GC/FID) using authentic standards of major constituents of the oils. Good fractionation results for citronella essential oil were achieved, affording complete removal of limonene, with a rich citronellal fraction and an output stream constituted mainly by citronellol and geraniol. Likewise, the use of the vacuum fractionation column allowed almost complete removal of limonene (∼0.7 wt% at column bottom) from the orange oil phase at the lowest operating pressure, 1 mbar, while the higher valencene content (20.5 wt%) was obtained at 10 mbar and reflux ratio of 1:1.     

Co-encapsulation of fish oil with phytosterol esters and limonene by milk proteins

Co-encapsulated microcapsules containing three lipophilic bioactive components (LBCs) including fish oil, phytosterols and limonene were studied and compared with those containing only fish oil. Milk proteins (whey protein isolate and sodium caseinate in a ratio of 4:1) were used as wall materials. Results show that good quality microcapsules can be obtained at inlet temperature of 170 °C and outlet temperature of 70 °C, with the wall to core ratio of 4:1. There was no significant different (p > 0.05) in the microencapsulation efficiency and the oxidation indicators (PV and AV) after the accelerated storage for both types of microcapsules. However, the retention of EPA and DHA in the LBCs-microcapsules was significantly higher (p < 0.05) than the fish oil microcapsules. The phytosterols content was unchanged but loss of limonene occurred after storage. The LBCs-microcapsules had better flavor/odour profile than the fish oil microcapsules after drying and storage.     

Characteristics of microcapsule of red ginger (Zingiber officinale var. Rubrum) essential oil produced from different Arabic gum ratios on antimicrobial activity toward Escherichia coli and Staphylococcus aureus

Essential oil has antimicrobial activity. Encapsulation of essential oil might affect its antimicrobial activity. The present study was aimed to study the characteristic of red ginger essential oil microcapsule obtained from varying Arabic gum ratios on the growth inhibition of E. coli dan S. aureus. Red ginger essential oil from steam distillation was coated using Arabic gum with ratio 1:3, 1:4, 1:5 (w/b). The 1:3 (v/w) ratio of red ginger essential oil and Arabic gum showed the best microcapsule characteristics with average inhibition diameter zones 5.67 mm for E. coli and 6.67 mm for S. aureus, and reduction of bacterial count for E. coli 1.8 log CFU/g and S. aureus 2.3 log CFU/g, yield of microcapsule 51.54%, water activity 0.207, water content 3.57%, solubility 97.46%, surface oil 0.08%, and particle size 258.2 µm. The major component of red ginger essential oil was ar-curcumene, zingiberen, β-bisabolene, β-sesquiphellandrene, and camphene.     

Comparative amino acid and fatty acid compositions of edible gums kondagogu (Cochlospermum gossypium) and karaya (Sterculia urens)

Gum karaya and gum kondagogu are the two important commercial tree gums of India. The amino acids and fatty acid profiles of gum kondagogu and gum karaya were investigated by preparing their corresponding N-O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatives for amino acids and direct trans-esterification of methyl esters for fatty acids and their subsequent analysis by a GC–MS method. The amino acids, such as, alanine, valine, methionine, tyrosine and tryptophan, were not detected in gum karaya as they were in gum kondagogu. Interestingly, the aspartic acid content (72.8 ± 3.45 μg/g) of gum kondagogu was higher than that of gum karaya (64.2 ± 2.44 μg/g). The ratios of saturated to unsaturated fatty acid in gum kondagogu and gum karaya were found to be 5:1, and 6.6:1, respectively. Among the unsaturated fatty acids, linoleic acid (1.8 ± 0.12 μg/g) and γ-linolenic acid (0.8 ± 0.05 μg/g) were detected only in gum kondagogu. Arachidic acid was not detected in gum karaya. Additionally, the presence of linoleic acid and γ-linolenic acid in gum kondagogu reinforces its nutritional value.     

In vitro retardation of glucose diffusion with gum extracted from malva nut seeds produced in Thailand

Mucilage of malva nut fruit has been used as traditional medicine in Thailand. Our laboratory has succeeded in extracting malva nut gum (MNG) from malva nut seeds by using alkaline-extraction method. The extract had higher gelling properties compared to water-extracted MNG. This research was aimed to investigate the effect of MNG on the retardation of glucose diffusion in in vitro dialysis processes. The results showed that alkaline-extracted MNG significantly (p < 0.05) reduced glucose content in dialysate compared to control containing no dietary fibre. MNG at 1% (w/w) concentration was more effective than that of 0.5% (w/w) concentration. The mixture of MNG and guar gum significantly (p < 0.05) reduced glucose in dialysate by 50–82% compared to that of control. In starch digestion process, the mixture of MNG and guar gum showed greater reduction of glucose (3–7 folds) in dialysate at 15–30 min.