Properties Of Extrudates Research Articles

Supercritical fluid extrusion: Die design and physicochemical properties of milk protein extrudates

Extrusion processing has been used to modify the functional properties of proteins. The protein-protein interactions, surface hydrophobicity, and rheological properties of milk protein concentrate extruded using dies of different geometries (circular, annular and slit) were quantified. With the same extrusion treatment history prior to the die, extrudates generated using dies with higher wall shear (slit 1.4 × 104 s−1 > annular 1.1 × 104 s−1 > circular 2.9 × 103 s−1) showed greater protein extractability, higher index of surface hydrophobicity, and enhanced water solubility index indicating significant breakdown of protein aggregates. Higher viscoelastic moduli (G' and G") and apparent viscosity were observed for slit die extrudate dispersions. However, low flow behavior indices (0.04–0.23(−)) and a high viscous activation energy (43 kJ/mol) of slit die extrudate dispersions implied their shear and temperature sensitivity, respectively. Thus, extrudate functionality can be optimized by selection of the appropriate die design.

Exploration of physicochemical properties and molecular interactions between cellulose and high-amylose cornstarch during extrusion processing

Incorporating fiber at high levels (>10%) into direct-expanded products with acceptable texture is challenging. Fundamental explanations for the interaction of starch and fiber and the cause of expansion reduction need further understanding for the effective incorporation of fiber into expanded products. This study aims to explain how cellulose content impacts the physicochemical properties of starch-based extrudates and the long-range and short-range molecular changes of starch. Mixtures of cornstarch (50% amylose) and cellulose were extruded using a co-rotating twin-screw extruder. Thermal and pasting properties of the raw mixtures were evaluated, and the physicochemical properties and microstructure of extrudates were determined. Long-range and short-range molecular changes of starch-cellulose mixtures before and after extrusion were observed by X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. The expansion ratio of extrudates reduced significantly as the cellulose content increased and had a strong negative correlation with crystallinity. Cell structures of starch-cellulose extrudates had a smaller and more uniform pore size but possessing a more ruptured matrix. FTIR spectra suggested that there was no covalent bonding interaction between starch and fiber after extrusion. Extrusion reduced the overall crystallinity compared to the raw mixtures. XRD showed that the crystallinity of the starch-cellulose extrudates increased as the cellulose content increased, and the XRD peaks representing cellulose remained unchanged. Cellulose could interfere with starch chain reassociation through intermolecular hydrogen bonding during the expansion process. Phase separation of starch and cellulose is likely to occur at high cellulose content, which could be another reason for the reduced expansion.

Реакционная экструзия нанокомпозитов на основе этиленовых сополимеров и минеральных наполнителей

The paper presents the results of a study of the influence of the temperature regime of reaction extrusion on the main physicomechanical characteristics of nanocomposites based on copolymers of ethylene with butylene and ethylene with hexene and natural minerals - clinoptilolite and vesuvian. The optimal temperature regime of extrusion of nanocomposites based on copolymers of ethylene and natural minerals was established. At a maximum extrusion temperature of 230 °C in the dosing zone, counterflow increases, which contributes to an increase in the residence time of the nanocomposite melt and, accordingly, to a decrease in extruder productivity. The possibility of mechanochemical synthesis of nanocomposites vulcanized with dicumyl peroxide on an extruder using monotreme technology has been proved. It was found that as a result of vulcanization of nanocomposites based on ethylene copolymers, a significant increase in the ultimate tensile stress and a decrease in the elongation at break are observed. With an increase in the maximum extrusion temperature in the extruder head to 230 °C, it does not lead to the appearance of a counterflow. At the same time, it was shown that with an increase in the temperature regime of extrusion of vulcanized nanocomposites over 200 °C, the time spent by the melt in the material cylinder practically does not undergo changes. A fundamental feature of the effect of chemical crosslinking with dicumyl peroxide on the processing process and the regularity of changes in the properties of nanocomposites are established. The probable mechanism of the vulcanization process in the melt of the polymer matrix and its selective effect on the reaction extrusion process, structural features and properties of nanocomposites are presented.

Optimization of Some Physical and Functional Properties of Extruded Soybean Crud Residue-base Floating Fish Feed

Effect of some extrusion factors on soybean crud residue-based floating fish feed was investigated. Extrusion was conducted at 20%, 25% and 30% moisture content level, die size of 2 mm, 4 mm and 6 mm and screw speed of 150 rpm, 200 rpm and 250 rpm. Pearson square method of fish feed formulation was used to attain a 35% protein content of catfish feed protein requirement. Optimized value of extrusion factors moisture content, die size and screw speed were 30%, 6 mm and 150 rpm respectively and optimized result of responses, expansion rate (ER) floatation rate (FR) sinking velocity (SV) specific mechanical energy (SME) swelling capacity (SC) water absorption index (WAI) water solubility index (WSI) hydration capacity (HC) and hydration index (HI) are 32.73%, 95.87%, 0.024 ms^-1, 16.97 KJ/kg, 1.73, 1.61, 2.76, 0.51, and 0.67 respectively. Feed moisture content and die size have the most significant effect on the physical and functional properties of extrudate. Coefficient of determination R² ranges from 0.65 to 0.96, lack of fit not-significant, desirability in optimization of 0.806, suggesting adequacy of research. Soybean crud residue base floating fish feed has been formed and evaluated with an outcome of high efficacy. This extruded produce can be used for both domestic and industrial scale of catfish feed production.

Effect of Flaxseed Oil Inclusion and Extrusion Cooking Parameters on Extruded Snack-food Physical and Functional Properties

Aims: Attempts were made to study flaxseed oil incorporated extruded snack by adopting response surface methodology (RSM) approach.
 Study Design: Central Composite Rotatable Design (CCRD).
 Place and Duration of Study: Department of Food Processing Technology, A.D. Patel Institute of Technology, Po Box 52, New Vallabh Vidya Nagar, Anand.
 Methodology: Feed moisture (12 -16%, wb), flaxseed oil (3-7%), extruder barrel temperature (115-145⁰C and screw speed (345 – 375 rpm) were selected as independent variable at three levels. The Central Composite Rotatable Design (CCRD) was employed to study linear, interactive and quadratic effect of selected independent variables on measured responses (expansion ratio ER, breaking strength BS, overall acceptability score OAA, starch-lipid complexing index CI).
 Results: The physical properties of extrudate (ER at 0.05 and BS at 0.10 level) and functional properties (OAA at 0.05 and CI at 0.01 level) were significantly influenced by flaxseed oil inclusion level. The quadratic effect of feed moisture and barrel temperature were found to be significant on each response (p<0.01). After numerical optimization, flaxseed oil of 6%, feed moisture content of 14.5% (wb), barrel temperature of 1300C and screw speed of 355 rpm were optimized.

Экструдирование растительного сырья для продуктов питания (обзор)

Introduction. The present review covers the issues of extrusion of plant raw materials in food industry. The authors analyzed foreign publications about various extrusion technologies, their rational parameters, and their effect on the properties of final products. Study objects and methods. The research featured extrusion methods of plant raw materials in food production. The review included scientific articles published in English in 2000–2020. Results and discussion. Extrusion is an effective processing method for plant raw materials in food industry. The analysis made it possible to define the effect of extrusion parameters on the components of plant raw materials. Extrusion increases digestibility of such plant components as protein and starch. High temperature, speed, and moisture are the optimal parameters for extrusion. High barrel temperature has a negative effect on vitamin and carotene content, while feed rate and screw speed are not important. Extrusion leads to complete mycotoxins reduction at critical temperatures. While high temperature and screw speed are important for process efficiency, they have a negative effect on the nutritional value of the final product. Conclusion. Optimal parameters of various raw materials and their compounds remain largely understudied, in spite of the fact that they are responsible for the balance between the required extrudate properties and nutritional value. Formation of nutrient complexes and their effect on the process parameters also require further research, especially in regard with protein-carbohydrate and amylaselipid complexes. In general, extrusion of plant raw materials remains a promising but largely neglected research topic in food science.

Conversion of heavy gasoil into ultra-low sulfur and aromatic diesel over NiWRu/TiO2–γAl2O3catalysts: Role of titanium and ruthenium on improving catalytic activity

This contribution deals with about selective conversion of heavy gas oils into middle distillates fuels that meet ultra-low sulfur and aromatic compound quality standards by using a novel NiWRu/TiO2–γAl2O3catalyst under typical hydrotreatment conditions. A diesel fuel fraction having sulfur, nitrogen and aromatics compound content of about 50 ppm, 10 ppm and 15 v%, respectively, was obtained when the reactor was operated atT = 370 °C,P = 12.4 MPa, LHSV = 0.5 h−1and H2/hydrocarbon ratio = 800 Nm3/m3. Titanium and ruthenium additives used in the preparation of the NiWRu/TiO2–γAl2O3catalyst, remarkably improved the catalytic activities for the hydrogenolysis, hydrogenation and hydrocracking reactions compared to the reference NiW/γAl2O3catalyst. The coprecipitation of titanium and aluminum hydroxides produced a catalyst support having greater surface area, pore volume and surface acidity. An improvement in mechanical properties of the support extrudates was also observed. Characterization analysis by XPS, AUGER and XRD techniques of the TiO2–γAl2O3support suggested the formation of an aluminum-titanate mixed phase (AlxTiyOz) having a non-well-defined stoichiometry. The NiW/TiO2–γAl2O3and NiWRu/TiO2–γAl2O3exhibited a greater surface dispersion of the supported nickel and tungsten species compared to the NiW/γAl2O3catalyst. The promoter effect of ruthenium on the NiW bimetallic system caused a strong increase in both hydrogenolysis and hydrogenation reactions. Hydrodenitrogenation and hydrocracking reactions were also favored by the increase in the hydrogenation capacity and in the surface acidity of the catalyst. The highest conversion levels for all investigated reactions were obtained when the NiWRu/TiO2–γAl2O3catalyst was prepared by co-impregnation of Ni and Ru in a second step. This catalyst showed sulfur tolerance properties when the reaction was conducted in the presence of different H2S partial pressures. The catalytic behavior of the NiWRu/TiO2–γAl2O3catalyst was explained by the existence of a promoting effect between separated Ni and Ru sulfides species and the NiWS phase (dual mechanism).

Influence of extrusion cooking on phytochemical, physical and sorption isotherm properties of rice extrudate infused with microencapsulated anthocyanin.

The effect of extrusion cooking on the quality of rice extrudate with infused microencapsulated anthocyanin was investigated. The moisture sorption isotherm of the extrudate was also studied. The rotatable central composite design was used to optimize the extrusion process and the optimized conditions were: screw speed, 121rpm; barrel temperature, 91.89°C; and moisture content, 22.03%. The extrudate showed anthocyanin content of 0.218mg/L; true density, 1.48g/cc; water activity 0.51, water solubility index, 7.49%; and specific mechanical energy, 31.39kJ/kg. The antioxidant activity and solubility of the extrudate were higher as compared with native extrudate. The moisture sorption isotherm of the extrudate was found to follow type III isotherm behavior according to the Brunauer-Emmett-Teller classification. The sorption isotherm was analyzed using several models and the Caurie and Peleg models were best fitted with the extrudate isotherm data. The present work manifested a way to develop antioxidant rich extrudate.

Effect of extrusion on physical and functional properties of millet based extrudates: A review

The aim of this review is to highlight the effect of extrusion on physical and functional properties of millet based extrudates. Extrusion is a combined thermo-mechanical process which causes gelatinization, breakdowns complex starch and protein structure of the food in short span of time. Merely changing the process conditions of the feed composition and moisture content, the cooking temperature along the extruder and the die and screw speed gives a variety of desired product. Various researchers have formulated different millet-based extruded snacks using pearl millet, finger millet, foxtail millet, kodo millet and sorghum and/or supplementation of major cereals and pulses. The studies shows the significant effect of machine and material parameters on physical and functional properties of extrudates including, expansion ratio, bulk density, water solubility index, water absorption index and specific length.

Properties of extruded cross-linked waxy maize starches and their effects on extruded oat flour

The objectives of this study were to study the extrusion of cross-linked waxy maize starches (CLWMS) with different cross-linking levels and their function as a secondary ingredient in extruded oat flour (OF) formulations. CLWMS (18 %) and OF (82 %) were hydrated to 20 % moisture content and subjected to twin-screw extrusion at the screw speed of 350 rpm. Low cross-linking level of CLWMS (0.05 % sodium trimetaphosphate/sodium tripolyphosphate) in OF formulation increased the void fraction and reduced the breaking strength of extrudates. The low cross-linked starch was more resistant to breakdown and had a higher pasting viscosity than the unmodified starch. Higher cross-linking levels of CLWMS restricted swelling of starch granule and increased the resistant starch level of OF formulation but had very poor structural and textural properties. Varying the level of cross-linking offers an alternative way to manipulate the structural, textural and nutritional properties of extrudates in snack and cereal applications.

Optimization, modeling, and characterization study for the physicochemical properties of raw banana and defatted soy composite extrudates

Novel raw banana and defatted soy composite extrudates were formulated to combat celiac enteropathy. The influence of four independent parameters viz. barrel temperature (BT: 60–80 °C), screw speed (SS: 200–300 rpm), moisture content (MC: 10–20%, wb), and defatted soy flour content (SFC: 0–32%) on physicochemical properties of extrudates were evaluated. Response surface methodology (RSM) identified the optimum extrusion conditions (80 °C BT, 200 rpm SS, 10% MC, and 32% SFC). Compared to RSM (R2:0.379–0.918), artificial neural network (R2:0.909–0.991) proved as a better tool for response prediction. Scanning electron microscopy confirmed the antagonistic effect of SFC addition on extrudate porosity. The addition of SFC decreased the crystallinity of the starch granules (71 to 49%), whereas, storage time had a positive effect (49 to 53%) on crystallinity of the composite extrudates. Fourier transform infrared spectroscopy analysis elucidated the secondary structures of protein in the composite flour which were degraded during the extrusion cooking.

Composition and Technological Properties of Clays for Structural Ceramics in Limpopo (South Africa)

This study evaluated the potential of raw clays from the Mukondeni region for structural ceramics and pottery based on traditional firing techniques. Physical properties were identified by particle size distribution, consistency limits, and clay activity. Mineralogical and chemical properties were investigated by X-ray diffraction (XRD) and X-ray fluorescence (XRF). Extruded clay bodies were fired at 900 °C. Technological characteristics were measured by weight loss (WL), bulk density (BD), dry linear shrinkage (DLS), fired linear shrinkage (FLS), water absorption (WA), and flexural strength (FS). The clays were low in <2 µm fractions (≤19%) and of medium to high plasticity with a clayey silt texture. Smectite was the dominant clay mineral while quartz and feldspar were major non clay minerals. The most abundant oxides were SiO2 (63.57–68.73%), Al2O3 (13.9–15.61%), and Fe2O3 (4.86–6.18%), whereas K2O, CaO, MgO, Na2O, TiO2, and P2O5 were depleted. Characterization based on the clay workability chart, Winkler’s diagram, and compositional ternary diagrams revealed acceptable extrusion properties and suitability for structural ceramics and earthenware. The clays showed acceptable WL, BD, LS, and WA, but unsatisfactory FS (≤1.08 MPa). Low mechanical strength was attributed to presence of smectites and inert nature of feldspar at 900 °C. Beneficiation through mixing with carbonate-rich raw materials is recommended.

Impact of Fermentation and Phytase Treatment of Pea-Oat Protein Blend on Physicochemical, Sensory, and Nutritional Properties of Extruded Meat Analogs.

Plant materials that are used for the production of extruded meat analogs are often nutritionally incomplete and also contain antinutrients, thus there is a need to explore alternative plant proteins and pre-treatments. This study demonstrates application of phytase and fermentation to a pea-oat protein blend with a good essential amino acid profile and subsequent texturization using extrusion cooking. Enzymatic treatment reduced the content of antinutrient phytic acid by 32%. Extrusion also degraded phytic acid by up to 18%, but the effect depended on the material. Differences in physicochemical, sensorial, and textural properties between untreated and phytase-treated extruded meat analogs were small. In contrast, fermented material was more difficult to texturize due to degradation of macromolecules; physicochemical and textural properties of extrudates were markedly different; sensory analysis showed enhancement of flavor, but also detected an increase in some unwanted taste attributes (bitterness, cereal and off-taste). Phytic acid was not degraded by fermentation. Analysis of volatile compounds showed extrusion eliminated volatiles from the raw material but introduced Maillard reaction products. Overall, phytase treatment and fermentation demonstrated the potential for application in extruded meat analogs but also highlighted the necessity of optimization of process conditions.

Steam vs. SC–CO2–based extrusion: Comparison of physical properties of milk protein concentrate extrudates

Milk protein concentrate (MPC) is an attractive high protein and low lactose containing ingredient. However, its utilization in extruded products remains a challenge because of its sensitivity to high temperature and shear. This study compares the physicochemical properties of MPC80 extrudates generated with steam vs. supercritical CO2 (SC–CO2)-based extrusion. Compared to steam, SC-CO2 extrudates prevented Maillard browning, evident in a significant (P < 0.01) increase in lightness (87.57–89.65), decreased yellowness (16.06–8.31), and increased whiteness (79.49–86.59) indices. SC-CO2 samples had a radial expansion ratio 52% higher than steam and correlated with a reduction in piece and bulk densities (0.21–0.07 g/cm3 and 0.16 to 0.04 g/cm3). The internal morphological structures visualized with SEM showed SC–CO2–expanded extrudates possessing substantially smaller cells and higher cell density. Texture analysis indicated that hardness and Young's modulus of SC-CO2 extrudates were significantly lower than those of the steam-expanded extrudates (35.71–18.35 N and 70.26 to 5.14 kPa).

Rheology and processing of polytetrafluoroethylene (PTFE) paste

AbstractThis is a review article on the paste extrusion of polytetrafluoroethylene (PTFE). The article begins with an overall presentation of the process. Important aspects related to this process are the physical properties of PTFE, its rheology, the morphological changes occurring during flow (fibrillation) that play a critical role on the dimensional stability of the final products, the geometrical characteristics, and types of dies used and temperature. PTFE is a compressible, zero Poisson's ratio material, and the mechanical properties of extrudates after extrusion are also discussed in view of fibrillation and Poisson's ratio.

Effects of Selected Tuber Crops Starch on Some Extrusion Properties of Fish Feed

This research evaluates the effect of feed formulation on fish feed properties with the aim of providing information on its water absorption and physical properties of the feed. The main objective of the study is to analysis the effects of the 3 tuber crops (dried cassava, potato and cocoyam flour) on the floatability of fish feed. The fish feed ingredients with varying percentage (40, 70 and 100) of starch from cassava, potato and cocoyam were extruded using a single screw extruder with constant screw speed (285 rpm). The resulting extrudates were subjected to extensive analysis of physical properties, which included moisture content, mass, surface area, volume unit density, bulk density and porosity. The water absorption properties include, the relative absorption rate (%), the water stability (%), the expansion ratio (%) and the floating ability rate (%) were also determined. There was a linear increment between the increase in starch with floatability and water absorption properties of cassava and cocoyam starch; however, a nonlinear decrease relationship existed in percentages (%) of potato starch. The formulation with 40% cocoyam has the highest floatability while the least floatability was observed from 100% potato at first 10 mins of observation. At 40% starches, 76.66% of cassava, 66.66% of potato and 100% of cocoyam afloat for the period of observation (10-120 mins). In conclusion, the formulation with 40% cocoyam was adjudged as the preferable feed composition based on its floatability. From the result, it can be recommended that cocoyam starch support the floatability of fish feed.

High methoxyl pectin enhances the expansion characteristics of the cornstarch relative to the low methoxyl pectin

The addition of dietary fiber pectin in extruded foods is beneficial for human health. However, pectins with different methyl ester levels may have different effects on the quality of extrudates. Hence, in this study, low and high methoxyl pectin were extruded with corn starch to investigate their impact on the expansion characteristics of corn starch. Pasting and thermal properties of the blends and structural characteristics and physical properties of extrudates were evaluated. Pectin interacted with starch molecules and restricted water adsorption into amorphous regions of corn starch, which influenced the gelatinization. Low methoxyl pectin increased the viscosity of the blends from 718.0 ± 8.7 to 773.0 ± 9.5 mPa·s, but high methoxyl pectin showed the opposite effect (from 718.0 ± 8.7 to 664.3 ± 4.7 mPa s). The extrudates of high methoxyl pectin and corn starch blends showed better quality than that of low methoxyl pectin and corn starch blends, especially on the expansion ratio (3.76 ± 0.01 for 15% HMP addition and 2.85 ± 0.04 for 15% LMP addition). The results of this work demonstrated that high methoxyl pectin addition, even at high levels, had little effect on the quality of corn starch extrudates compared to the one without pectin addition.

Extrusion of fermented rice-black gram flour for development of functional snacks: Characterization, optimization and sensory analysis.

Considering the health benefits of fermentation, extrusion of fermented rice black gram mix flour can lead to developing nutritionally rich expanded snack. Hence, present study details the effect of various extrusion process variables, barrel temperature (100, 110, 120°C), screw speed (250, 300, 350rpm) and die opening diameter (3, 3.5mm) on physicochemical and bioactive properties of extrudates from fermented rice-black gram flour (Rice flour: black gram flour = 3:1). Results indicated that temperature rise led to the production of a more expanded product with higher water solubility index (WSI) and lower water absorption index (WAI). Higher puffing, WSI,and bioactive content wereobserved in 3mm die opening extrudates. Interestingly, extrusion cooking of fermented flour has shown a remarkable increment in phenolic content and antioxidant activity from 63.47 up to 210.3 and 7.28 up to 13.889mg GAE/100g, respectively. However, rise in barrel temperature showed a negative impact on bioactive attributes. Further, the optimal conditions determined by numerical optimization method for development of fermented flour-based extrudates having superior functional and enhanced bioactive properties were found to be 100°C temperature, 289rpm of screw and 3mm die diameter. Principal component analysis indicated that bulk density-moisture content and phenolic content-antioxidant activity were highly positively correlated, while expansion ratio-bulk density was negatively correlated. The microstructure of extrudates showed continuous and compact structure lacking starch granules. The fuzzy logic analysis revealed that fermented flour-based extruded product had superior overall acceptability over unfermented flour extrudates.

Effect of process parameters on the functional and physicochemical properties of extrudates enriched with starch-based nut flour

Widening the range of products produced on the basis of agricultural raw materials and improving the quality of these products and increasing their nutritional value ”‹”‹represent urgent challenges. Therefore, the production of new mass consumption products with high nutritional and biological value brings to the fore the use of local nut flour as an enriching supplement in innovative technological processes. The high nutritional value of nuts (nuts, walnuts, and peanuts) is due to their chemical composition, including lipids, a large amount of soluble proteins that are well absorbed by the human body, sufficiently large quantities of vitamin B1 and a small amount of vitamins PP and E. It is known that in peanut grains, lipids have a balanced composition of fats and acids, as well as sufficiently large amounts of essential amino acids, which makes their protein composition closer to that of animal proteins. This study considers the influence of thermoplastic extrusion parameters on the functional and physicochemical properties of extrudates in their formation process. The technological and design parameters of the process and their variation ranges are based on studies conducted on model systems. The ratio of the extrusion mixture components (formulation) is also developed. Based on the methodology for multifactorial experimental design, the variation of the volume weights, expansion rates, and mechanical specific energy expenditure of porous extrudates enriched with starch-based nut flour is studied. It has been established that the best quality indicators of the products are achieved with the minimum volume weight and the maximum expansion rate.

Vacuum‐assisted extrusion of red rice ( bao‐dhan ) flour: Physical and phytochemical comparison with conventional extrusion

The effect of vacuum-assisted extrusion cooking on the properties of red rice extrudate was investigated. The rotatable central composite design was employed to determine the effect of independent variables on dependent variables. The process was optimized using an artificial neural network (ANN) and genetic algorithm (GA) The sensitivity analysis of independent variables was conducted and the screw speed showed the highest contribution on the product quality. The optimum condition obtained by ANN and GA was 77.5°C barrel temperature, 32.5% feed moisture, 350 rpm screw speed, and 300 mmHg vacuum level. The developed process was compared with the conventional extrusion process without employing a vacuum in terms of physicochemical and phytochemical properties. The extruded was contented 3.89 mg/L of anthocyanin, 0.021 µm/L of cyanidin-3-glucoside, and 3.21 µm/L of peonidin-3-glucoside. The vacuum-assisted extrusion cooking showed to develop expanded extrudate at low temperatures with higher phytochemical retention. Practical applications Extrusion cooking generally considers as a high-temperature short time process. Due to high temperature and high shear, most of the bioactive compounds are deteriorated during extrusion cooking. Therefore, extruded are considered unhealthy for consumers. The outcome of the present investigation can enhance the retention of bioactive compounds in extruded products. The vacuum-assisted extrusion could expand the extrudate at low temperatures and enhance the retention of bioactive compounds.