Increasing Feed Moisture Content Research Articles

The effects of feed moisture and dried coconut meal content on the physicochemical, functional, and sensory properties of gluten-free Riceberry rice flour-based extruded snacks

The objective of this study was to develop an expanded snack from Riceberry rice flour (RBF) and dried coconut meal (DCM), a by-product of coconut milk production, using a twin-screw extruder. A 3 x 3 factorial design was employed to investigate the effects of feed moisture contents (18, 21, and 24%) and DCM levels (0, 5, and 10%) on the physicochemical, functional, and sensory properties of the products. The results showed that increasing feed moisture content significantly reduced the cold peak viscosity but had no significant effect on the hot peak viscosity. DCM was the dominant factor affecting the hot peak viscosity. The substitution of DCM led to a decrease in the expansion of the extrudates while increasing the L* and b* values. The texture parameters were affected by both feed moisture and DCM, where increased feed moisture resulted in more rigid structures with higher density and hardness but lower crispiness. Antioxidant levels in the final product decreased by approximately 64 to 70% and 10 to 25%, as determined by DPPH and FRAP assays, respectively, compared to the initial RBF. However, the antioxidant levels remained high in the final product. Feed moisture content had no effect on the antioxidant activity as measured by the DPPH and FRAP assays. The total phenolic content (TPC) of the extrudates decreased as feed moisture and DCM content increased. Furthermore, the anthocyanin content (ATC) decreased when RBF was substituted with DCM. The sensory evaluation revealed that the product with 18% feed moisture content and 10% DCM had the highest overall liking score. These findings offer valuable insights into the potential use of a twin-screw extruder for developing expanded snacks from RBF and DCM and could be useful for further research in this area.

Effects of particle size distribution and processing conditions on the techno-functional properties of extruded soybean meal

Soybean meal (SBM) is a protein-rich, soybean oil industry by-product which can be extruded for improved techno-functionality and potential utilization as a food ingredient. The effects of SBM particle size distribution [PSD] (small, medium and large), extrusion feed moisture content (15, 21 and 27 g water/100 g dry SBM) and barrel temperature (110, 130 and 150 °C at the die) on techno-functional properties of SBM extrudates were investigated. A decrease in barrel temperature from 150 to 110 °C generally improved nitrogen solubility index, gel forming capacity, oil holding capacity and emulsion capacity of extrudates. In addition, increasing feed moisture content from 15 to 27 g water/100 g dry SBM generally enhanced oil and water holding capacities. Nitrogen solubility index of extrudates made from large PSD feed was generally higher than that of medium PSD extrudates. PSD of SBM also affected the torque and specific mechanical energy requirements during extrusion cooking, SBM with large PSD requiring a higher level of mechanical energy input to be processed when compared to that with medium PSD. This work provided a comprehensive understanding of how feed particle size, extrusion moisture and barrel temperature can be manipulated to provide new opportunities in producing novel food ingredients from SBM.

Effects of extrusion parameters on physicochemical properties of third generation corn snacks expanded by microwave heating

Corn grits were extruded then extrudates were expanded by microwave-heating. Effects of addition of xanthan gum (XG) (0%–1%), feed moisture content (37%–47%) and screw speed (100–300 rpm) level on physicochemical properties of snacks were evaluated with response surface methodology (RSM). All suspensions of expanded samples exhibited shear-thinning behavior. Apparent amylose content of samples ranged from 22.47% to 37.97%. Screw speed and feed moisture content had positive effect on apparent viscosity and amylose content but XG level had negative effect on them. Increasing screw speed increased expansion and luminosity but decreased browning index and total color difference. Increasing feed moisture content resulted in reduced expansion, luminosity but increased browning index. In contrast to the initial effect, expansion and browning index decreased when XG addition level was above 0.5%. Optimum conditions were determined to obtain the maximum values for expansion index and luminosity and minimum value for the total color difference by desirability function. They were found as 300-rpm screw speed, 47% feed moisture content and 0.34% XG level. Practical applications Extrusion process occupies an important place in the food industry for production of snacks and breakfast cereals. This technology is especially preferred due to its versatility, high productivity, relative low cost energy efficiency for snack production. However, extrusion process conditions (feed moisture, screw speed, and barrel temperature) and additives used in this process have critical importance for snack characteristics. Gum addition provides lubrication during extrusion process. Expansion and color characteristics of product may be change according to gum addition level. Response surface methodology (RSM) can be used as an optimization tool to achieve a better product considering multiple quality characteristics for snacks. A better evaluation of simultaneous interactive effects of process variables on the products can be achieved with RSM technique. Application of RSM in this study may be employed as baseline information for further scale-up of third generation snack production with several additives and under different production conditions.

Effects of extrusion operating conditions and blend proportion on the physicochemical and sensory properties of teff-rice blend extruded products

The effects of extrusion conditions, teff-to-rice blend ratio (25-100%), feed moisture content (21-25%) and barrel temperature (130- 150°C) on the physico-chemical properties and the sensory attributes of extruded product from teff-rice blend was investigated. The physico-chemical properties (specific length, bulk density, expansion, water absorption index (WAI), water solubility index (WSI) and hardness), and sensory acceptability (flavor, color, texture and overall acceptability) were significantly (p<0.05) influenced by the extrusion conditions. Increasing barrel temperature resulted in higher expansion, lower density, reduced hardness and higher WAI, and WSI. Increase in the proportion of teff resulted in increased density, hardness, and WSI whereas increase in teff proportion brought about a decrease in expansion and WAI. Increasing feed moisture content resulted in higher density, lower expansion, higher WAI, lower WSI, higher hardness and lower crispness. The sensory scores reduced with increase in the proportion teff. The numerical optimization revealed that the optimal extrusion conditions for the best result were extrusion temperature of 150°C, feed moisture content of 21.2% and blending ratio of 40% teff with a desirability value of 0.901. The graphical optimization revealed that the best results were found between 140 to 150°C, 21 to 22% feed moisture and 25 to 46% of teff proportion.

Influence of Extrusion Conditions on Techno-functional Properties, Phytochemical Contents and Antioxidant Activity of Rice-based Extrudates Containing Powder of Purslane (Portulaca oleracea L.) and Jew's Mallow (Corchorus olitorius L.) Leaves

Purslane (Portulaca oleracea L.) and Jew's mallow (Corchorus olitorius L.) leaves have several desirable characteristics as functional ingredients for the production of healthy new foods. In this study, the influence of extrusion conditions including material type, feed moisture content and barrel temperature on techno-functional properties, phytochemical contents and antioxidant activity of rice-based extrudates containing purslane and Jew's mallow leaves powder was investigated. Inclusion of purslane and Jew's mallow leaves powder into the rice flour formula significantly affected the techno-functional, physical properties, phytochemicals and antioxidants activity of the resultant extrudates. Increasing feed moisture content resulted in extrudates with higher bulk density (BD) and breaking strength (BS) and lower phytochemicals content. Higher barrel temperature resulted in extrudates with higher techno-functional properties. Furthermore, statistical analyses revealed that the interactions between process variables were significant. Correlation relationships between techno-functional, physical properties, antioxidant activity and phytochemical contents were noticed. These results will be used to help define optimized process conditions for controlling and predicting qualities and characteristics of extruded products containing purslane and Jew's mallow leaves powder.

Modification of the digestibility of extruded rice starch by enzyme treatment (β-amylolysis): An in vitro study

The rate and extent of starch hydrolysis in the digestive tract impacts blood glucose levels, which may influence an individual's susceptibility to diabetes and obesity. Strategies for decreasing starch digestibility are therefore useful for developing healthier foods. β-amylase is an exo-hydrolase that specifically cleaves α-1,4 glycosidic linkages of gelatinized starches. In this study, starch granules were disrupted by extrusion under different feed moisture conditions, and then subjected to β-amylolysis. The degree of starch gelatinization increased with increasing feed moisture content during extrusion, leading to faster β-amylolysis. The hydrolysis of in vitro starch digestion study was reduced for extruded samples treated with β-amylase, which was attributed to an increase in resistant starch (RS) after β-amylase treatment. Indeed, X-ray diffraction (XRD) indicated that the crystalline structure in the extruded starch was either partially or fully lost after β-amylase treatment. Similarly, Fourier transform infrared (FTIR) analysis indicated there was a higher level of amorphous regions in the starch after β-amylase treatment. Overall, our results suggest that enzymatic treatment of extruded starch with β-amylolysis reduces the ratio of crystalline-to-amorphous regions, which increases the level of resistant starch, thereby slowing down digestion. These results have important implications for the development of healthier starch-based foods.

The effect of extrusion conditions on the functional properties of defatted cake of sunflower-maize based expanded snacks

The effect of extrusion conditions, including feed moisture content (14–20%), screw speed (300–500 rpm), and barrel temperature (120–180oC) on the functional properties (water absorption index (WAI), and water solubility index (WSI), fat absorption capacity (FAC) and foaming capacity) and sensory properties (color, appearance, flavor, overall acceptability and textural characteristics) of an expanded sunflower snack was investigated. Extruded snacks were prepared by substituting maize flour with developed texturized flour of sunflower at 0–40% levels. Protein content increased to 13.83% in snacks prepared with 10% texturized sunflower meal as compared to the control i.e., 7.55%. Fibre content increased while protein digestibility improved with increased level of incorporation of texturized defatted sunflower flour in extruded snacks making. Increasing feed moisture content results in extrudates with lower expansion, lower WAI, higher WSI, higher hardness and lower sensory acceptability. Increasing screw speed caused slight reduction of density and hardness of sunflower extrudate. Feed moisture had positive while screw speed and barrel temperature had negative influence on WAI. Negative coefficient of linear terms of moisture and screw speed indicated that WSI decreased with increase in these variables. Higher moisture content in extrusion process could diminish protein denaturation which lowered WSI values.

Extrusion 제조 조건에 따른 쌀 스낵 제품의 이화학적 품질특성

Physicochemical properties of rice-based expanded snacks extruded with rice flour, high amylose starch, and isolated soy protein were investigated using a twin-screw extruder. The ingredients were extruded at various feed moisture contents (19~23%) and screw speeds (200~400 rpm) at a constant feed rate (43.4 kg/hr). Bulk density and apparent density of rice snacks were 0.06~0.21, and 0.55~0.65 respectively. Bulk density, apparent density, water absorption index, and breaking strength of rice snacks increased with increasing feed moisture content and decreas- ing screw speed. However, expansion and water solubility index of rice snacks increased with decreasing feed moisture content and increasing screw speed. Hunter's color L values of rice snacks was lower with increasing screw speed at feed moisture contents of 19% and 21%, but was not significantly different from a feed moisture content of 23%. On the other hand, a and b values of rice snacks were higher with increasing screw speed a feed moisture content of 19%. X-ray diffraction intensity of rice snacks decreased with decreasing feed moisture content and increasing screw speed. X-ray diffraction of rice snacks was V-type at feed moisture contents of 19% and 21% and screw speeds of 300, and 400 rpm. In the microstructure of the cross section of rice snacks, air cells in rice snacks were not well formed, and cell walls were thicker with increasing feed moisture content and decreasing screw speed.

Hull-less barley flour supplemented corn extrudates produced by conventional extrusion and CO2 injection process

Abstract The effects of feed moisture content (20, 25%), exit–die temperature (80, 130 °C), and extrusion-cooking method (with/without CO 2 injection) on β-glucan (BG) levels and physicochemical properties of hull-less barley flour (HBF) supplemented (15, 30, 45%) corn extrudates were investigated. The highest HBF supplementation level (45%) resulted in higher BG levels (2.87–3.28%) in all extrusion conditions. In general, increasing feed moisture content from 20 to 25% and exit–die temperature from 80 to 130 °C resulted in small increases in enzyme resistant starch type-3 (RS 3 ) levels. However, the investigated extrusion conditions did not form substantial amount of RS 3 and the highest RS 3 content was 540 mg/100 g. Lower feed moisture content and higher exit–die temperature resulted in higher water solubility (WS) and lower water-binding capacity (WBC) values. Cold-paste viscosity (CV) was observed in all extrudates. High WS and WBC values of extrudates and the existence of CV values in RVA curves indicated complete starch gelatinization. Industrial relevance CO 2 injection has been proved as a reliable alternative method to the conventional extrusion process used in the breakfast cereals and snack food industry. The overall quality of the product processed by CO 2 injection was comparable to that of the current process. The extrudates produced by CO 2 injection method had more uniform expansion and smoother surface. CO 2 injection did not have a reducing effect on β-glucan levels; however, it is expected to result in a better retention of heat labile micronutrients and hence more healthy food products.

Effects of formulation, extrusion cooking conditions, and CO2 injection on the formation of acrylamide in corn extrudates

Acrylamide is a possible carcinogen and known to form in heat-treated carbohydrate-rich foods. This study was designed to investigate the effects of different ingredients (reducing sugars, chemical leavening agents, citric acid), processing conditions (feed moisture content: 22, 24 or 26%, exit die temperature: 110, 150 °C), and extrusion cooking methods (with or without CO2 injection) on acrylamide formation. The type of reducing sugar did not have a considerable effect on acrylamide formation, while increased exit die temperature had a promoting effect. Addition of chemical leavening agents (sodium bicarbonate and ammonium bicarbonate) into formulations increased acrylamide formation levels. The addition of citric acid prevented acrylamide formation, but its effect on textural properties was detrimental. Acrylamide levels of extrudates decreased gradually with increasing feed moisture in all formulations. Acrylamide content of extrudates produced with 22% feed moisture decreased by 61% in the CO2 injection method compared to conventional extrusion. Furthermore, an 82% decrease in acrylamide content was observed with the combined effect of CO2 injection and increasing feed moisture content from 22 to 24% and decreased below the limit of quantification with a further increase in feed moisture. A substantial decrease in final acrylamide level is probably due to restriction of two major steps of acrylamide formation: dehydration and decarboxylation.

Effect of Thermo-extrusion Process Parameters on Selected Quality Attributes of Meat Analogue from Mucuna Bean Seed Flour

ABSTRACT Flour from mucuna beans ( Mucuna pruriens ) were used in producing texturized meat analogue using a single screw extruder with the intention to monitor modifications on some functional properties of the extrudate. Response surface methodology based on Box Behnken design at three levels of barrel temperature (110, 120, 130°C), screw speed (100, 120, 140 rpm) and feed moisture content (44, 47, 50%) were used in 17 runs. Regression models describing the effect of process variables on the product quality attributes were obtained. Result obtained showed that the moisture contents of the meat analogue samples decreased from 13.23 to 6.53%. Increasing feed moisture content resulted in extruded meat analogue with a higher density (0.988), water absorption index (WAI) (2.30), oil absorption index (OAI) (2.350), swelling power (3.47) and lower lateral expansion (0.84). Lateral expansion, OAI and swelling power increased as barrel temperature increased with peak values of 1.39, 2.39 and 3.47 respectively, while bulk density and WAI decreased. The product functional responses with coefficients of determination (R 2 ) ranging between 0.658 and 0.894 were most affected by changes in barrel temperature and feed moisture and to lesser extent by screw speed. Optimization results based on desirability concept indicated that a barrel temperature of 120.15°C, feed moisture of 47% and screw speed of 119.19 rpm would produce meat analogue of preferable functional properties.

Influence of twin-screw extrusion on soluble arabinoxylans and corn fiber gum from corn fiber

The effect of feed moisture content and screw speed in the extrusion process with and without chemical pretreatment of corn fiber was investigated. Different chemical pretreatment methods (NaOH and H2 SO4 solution) were compared. The improvement of reducing sugar, soluble arabinoxylans (SAX) content and the yield of corn fiber gum was measured. A high reducing sugar content was obtained in the filtrate fraction from the extruded destarched corn fiber (EDCF) with H₂SO₄ pretreatment. Feed moisture content most effectively improved both reducing sugar and SAX content of filtrate. Increasing feed moisture content and screw speed resulted in a higher SAX content in the filtrate of the EDCF with NaOH pretreatment. The SAX content of the residual solid from the EDCF with NaOH pretreatment was higher compared to H₂SO₄ pretreated and unpretreated samples and significantly increased with decreasing feed moisture content. The screw speed did not have a major impact after enzyme hydrolysis. The yield of corn fiber gum was increased by 12% using NaOH pretreatment combined with extrusion process as compared to the destarched corn fiber. The results show the great potential of the extrusion process as an effective pretreatment for disruption the lignocelluloses of corn fiber, leading to conversion of cellulose to glucose and hemicelluloses to SAX and isolation of corn fiber gum.

Effects of Waxy Rice Moisture Content and Rate of CO2 Injection on Characteristics of Extruded Pellets and Vacuum‐Puffed Yukwa (a Korean Traditional Snack)

ABSTRACTExtrusion with CO2 injection was developed to simplify the process of producing vacuum‐puffed yukwa (rice snacks). The effects of feed moisture content and CO2 injection on the characteristics of extruded pellets (maximum viscosity and degree of gelatinization) and vacuum‐puffed yukwa (expansion ratio, bulk density, hardness, and color) were investigated. Higher feed moisture increased the size of vacuum‐puffed yukwa and the degree of gelatinization, whereas the maximum viscosity decreased. Maximum viscosity and gelatinization degree of extruded pellets were highly correlated with expansion ratio, bulk density, hardness, and color values of vacuum‐puffed yukwa. Increasing feed moisture content significantly increased expansion ratio but decreased bulk density and hardness. CO2 injection decreased bulk density and hardness of vacuum‐puffed yukwa.

The effect of extrusion conditions on mechanical-sound and sensory evaluation of rye expanded snack

Rye-based extrudates were produced according to different conditions of barrel temperature (150°C and 190°C) and feed moisture content (12% and 16%) using a 22 factorial design. A combined mechanical and acoustic method was employed using a texture analyzer (TA-XT Plus, Stable Micro Systems) in combination with the acoustic envelope detector (AED), to describe the influence of extrusion parameters on the properties of extrudates. The results showed with increasing extrusion cooking temperature increasing number of force and number of sound peaks but decreasing maximum forces. Moreover the thickness of the cell wall decreased with increasing extrusion cooking temperature. All these trends were reversed with increasing feed moisture content. The results show further significant interactions, which means that the effect of barrel temperature depends on the feed moisture content and vice versa. Additionally, the quantitative descriptive analysis (QDA) was applied to examine the products in terms of sensory properties. The data were analyzed by principle component analysis (PCA) in order to investigate the relationship between sensory attributes and the instrumental data. The PCA showed a positive correlation between the sensory parameters hardness and sound intensity of crunchiness and the instrumental parameters force area, mean force, maximum force, and negative correlations between the number of sound peaks, mean sound peak, number of force peaks and crunchiness.

Effect of process and machine parameters on physical properties of extrudate during extrusion cooking of sorghum, horse gram and defatted soy flour blends

Extrusion cooking of sorghum (Sorghum vulgaris), horse gram (Dolichos biflorus) and defatted soy (Glycine max) flour blends was done to prepare snacks by using a Brabender single-screw laboratory extruder. The combined effect of moisture content, blend ratio of feed, barrel temperature and screw speed of extruder on physical parameters of extrudate was studied. It was observed that 15% moisture content of feed, 80:10:10 (sorghum flour: horse gram flour: defatted soy flour) of blend ratio, 130°C barrel temperature and 130rpm of screw speed gave the highest sectional expansion index and longitudinal expansion index of extrudate, while 12% moisture content, 75:15:10 of blend ratio of feed, 135°C of barrel temperature and 135rpm of screw speed gave lowest bulk density of extrudate. A central composite rotable design (CCRD) of response surface methodology was used to develop prediction model. Second order quadratic regression model fitted adequately in the variation. The significance was established at p ≤ 0.05. It was also observed that increasing feed moisture content results in a higher density and lower expansion of extrudate. Increasing barrel temperature and screw speed reduced density but increased expansion of extrudate.

Chemical cross-linking and molecular aggregation of soybean protein during extrusion cooking at low and high moisture content

Soybean protein isolate (SPI) was extruded using a co-rotating twin-screw extruder at low (28%) and high (60%) moisture content. Dead-stop operation was employed to obtain samples from different zones of the extruder. The protein solubility of extrudate was analyzed based on 8 different combinations of chemical bond-breaking solutions, which contained only phosphate buffer (P); two reagents, i.e. sodium dodecyl sulfate (SDS) in P (P + S), urea in P (P + U) and 2-mercaptoethanol (2-ME) in P (P + M); three reagents, i.e. (P + S + U), (P + U + M) and (P + M + S); four reagents, i.e. (P + S + U + M). Based on the protein solubility in the combined extraction solutions, each specific chemical bond and their interactions responsible for supporting the extrudate structure were further analyzed. The aggregation of protein subunits in extruded sample was investigated by using SDS-PAGE electrophoresis. The results showed that hydrophobic interactions, hydrogen bonds, disulfide bonds and their interactions collectively hold the structure of extrudate; and the importance of non-covalent bonds outweighs covalent bonds. Increasing feed moisture content could increase the interactions between disulfide bonds and hydrogen bonds and between disulfide bonds and hydrophobic interactions ( p < 0.05), reduce the degree of aggregation and the difference in protein–protein interactions and protein subunits among different zones within the extruder.

The effect of extrusion conditions on the functional and physical properties of wheat-based expanded snacks

The effect of extrusion conditions, including feed rate (20–32 kg h −1), feed moisture content (14–22%), screw speed (180–320 rpm), and barrel temperature (100–140 °C) on the functional properties (density, expansion, water absorption index (WAI), and water solubility index (WSI)) and physical properties (density, expansion and textural characteristics) of an expanded wheat snack was investigated. Increasing feed rate results in extrudates with a higher hardness and lower energy to puncture the samples. Increasing feed moisture content results in extrudates with a higher density, lower expansion, lower WAI, higher WSI, higher hardness and lower puncture energy. Increasing screw speed caused slight reduction of density and hardness of wheat extrudate. Higher barrel temperature reduced density, WAI, and hardness, but increased the WSI and puncture energy of extrudate.

The effect of extrusion conditions on the physicochemical properties and sensory characteristics of rice-based expanded snacks

The effect of extrusion conditions, including feed rate (20–32%), feed moisture content (14–22%), screw speed (180–320 rpm), and barrel temperature (100–140 °C) on the physicochemical properties (density, expansion, water absorption index––WAI), and water solubility index (WSI) and sensory characteristics (hardness and crispness) of an expanded rice snack was investigated. Increasing feed rate results in extrudates with a higher expansion, lower WSI, and higher hardness. Increasing feed moisture content results in extrudates with a higher density, lower expansion, higher WAI, lower WSI, higher hardness and lower crispness. Higher barrel temperature increased the extrudate expansion but reduced density, increased the WSI and crispness of extrudate. Screw speed had no significant effect on the physicochemical properties and sensory characteristics of the extrudate.

Effects of extrusion variables and starch modification on the puffing characteristics of yam ( Dioscorea alata) flour

The viability of extruding yam flour and the effects of extrusion temperature, feed moisture content, particle size and added amylose or amylopectin on the puffing characteristics of yam flour were investigated. Extrusion temperature < 100°C, feed moisture content >10% and any level of added amylose depressed product expansion. Product firmness and density decreased with increasing extrusion temperatures but increased with increasing feed moisture content above a critical limit of 9%. In general, feed particle size and addition of amylopectin did not affect the characteristics of yam flour extrudates. Yam flour can be successfully extruded with maximum expansion at a feed moisture range of 8–10% using extrusion temperatures of 100–115°C.