Gelatinization Research Articles

Клейстеризація картопляного крохмалю способом in vitro за надмірного вмісту води. 1. Кінетика процесу в ізотермічних умовах

The wide use of starches in the food industry determines their comprehensive study over many years. One of the key problems that need to be solved for the improvement of food technologies in which starch is used is the definition of the basic laws of the kinetics of the gelatinization process of starches. The purpose of this work was to determine the kinetic parameters of the gelatinization process of native potato starch with excessive water content in the reaction mixture (the modulus is 10 g/l) and to select the appropriate kinetic model. It was found that the kinetics of the gelatinization process of native potato starch is described by the Kruger-Ziegler equation. It is shown that the dependence of the rate constant of the gelatinization process on the temperature in Arrhenius coordinates has the shape of a convex curve. It can be assumed that at a temperature below 70 °С the process proceeds in the kinetic region with the limiting stage of the chemical reaction at the interface of the phases and when the temperature increases then transition to the diffusion region occurs. It is assumed that the essence of the specified chemical reaction means the formation or destruction of hydrogen bonds during the interaction between water molecules and amylose. The values of the imaginary activation energy of the gelatinization process calculated from experimental data are 191.3 kJ/mol in the temperature range of 60—70 °С and 22.2 kJ/mol in the temperature range of 80—90 °С. The high values of the activation energy at a temperature below 70 °С can be explained by the energy spent on breaking hydrogen bonds between the OH groups of amylose macromolecules. It is proposed to intensify the process of gelatinization of starch by increasing the temperature and using a catalyst at temperatures below 70 °С. If the process is carried out in the area of high temperatures, then its intensification can be achieved by grinding starch granules and increasing the mixing speed of the starch suspension.

Development and characterization of antioxidant composite films based on starch and gelatin incorporating resveratrol fabricated by extrusion compression moulding

Starch/gelatin (SG) films incorporated with resveratrol (RES) at various concentrations (0%–20%, w/w, on the weight of starch and gelatin) were developed via thermal extrusion followed by compression moulding. The SG based films were characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, together with the determination of optical, physical, thermal, and antioxidant properties of the films. SEM images showed the SG films containing RES had a higher surface roughness than that without RES, which was also confirmed by the three-dimensional surface topography images. The FTIR analysis revealed the existence of physical interactions among starch, gelatin, and RES through hydrogen bonding. The incorporation of RES significantly increased the thickness, opacity, and tensile strength of the films, while decreasing their transmittance, water solubility, water vapor and oxygen permeability. Furthermore, the elongation at break, surface hydrophobicity and thermal stability of the films also enhanced to some extent after addition of RES. More importantly, the composite films showed excellent antioxidant activity proportional to the RES concentration, and all films showed good anti-permeate property for oil without or with RES. Consequently, the SG film containing 20% RES with the highest oxygen barrier property and antioxidant activity could effectively reduce oxidative rancidity of soybean oil stored at 50 °C for 24 days when compared to SG film without RES and control sample (without film). To sum up, the thermoplastic processed SG films incorporating RES exhibited adequate properties for food packaging such as oil products which are highly susceptible to oxidation.

Effects of Xanthan Gum Addition and Extrusion Parameters on Properties of Starch‐Based Fried Corn Extrudates

AbstractStarch‐based corn grits are extruded and then the extrudates are fried to development for corn snacks with low oil content, improved texture, and preserved color characteristics. Effects of screw speed (100–300 rpm), feed moisture (37–47%), and xanthan gum (XG) level (0–1%) on expansion, oil absorption, hardness, color, and microstructural properties of fried extrudates are examined. Increased screw speed increases expansion index (EI) due to enhanced starch gelatinization. Elevated feed moisture content increases EI as a result of the low solubility index of starch‐based extrudates. The oil absorption of extrudates increases as screw speed and moisture content are elevated as a result of holes in the surface after frying. On the other hand, the incorporation of XG decreases oil absorption due to reduced holes on the surface. Hardness values range from 7.58 ± 0.47 to 42.26 ± 1.44 N. Increasing moisture content decreases the hardness of fried extrudates while increasing screw speed results inan increase in hardness. The incorporation of XG increases the hardness of extrudates. Increased screw speed, feed moisture, and XG ratio increase the lightness value and decrease the redness value. Browning index (BI) is decreased with an increase in feed moisture and XG level.

Green alternative for sodium metabisulfite substitution: Comparison of bacterial and fungal proteases effect in hard biscuit making.

Sodium metabisulfite is one of the most employed reducing agents in hard biscuit making. The recent results about its adverse effects on human health have pushed us to look in new safer and greener directions. Two different proteases, from distinct strains (bacterial and fungal), were selected and their effects on the dough thermomechanical performances, texture, and structure of the hard biscuits were compared with those obtained from the sodium metabisulfite. Doughs treated with fungal protease showed higher stability during mixing and higher consistency throughout the heating stage. On the other hand, bacterial protease had the greatest weakening effect on protein with a marked reduction of starch gelatinization. Doughs processed with fungal enzymes reached similar values to those containing sodium metabisulfite. In terms of hardness, no significant (p < 0.05) differences were found between biscuits made with bacterial protease and sodium metabisulfite. Analysis of the volumetric characteristics highlighted that bacterial enzymes gave higher values of specific volume and surface area. Regarding the structure of the hard biscuits, sodium metabisulfite produced a more uniform structure with fewer and smaller pockets as compared with the samples treated with proteases.

Interactions between sorghum starch and mushroom polysaccharides and their effects on starch gelatinization and digestion

This study aimed at gaining insight into the mechanism of interactions between sorghum starch and mushroom polysaccharides (MPs) obtained from three cultivars Lentinula edodes (LEP), Auricularia auricula (AAP), and Tremella fuciformis polysaccharides (TFP) in relation to gelatinization, retrogradation and digestibility of starch, and microstructures before and after digestion. MPs decreased the degree of gelatinization, activation energy (retrogradation energy), and digestibility of sorghum starch, whilst they increased the particle size of digesta in a concentration dependent manner (0.15–0.6%, w/v). Confocal laser scanning microscopic (CLSM) images of starch suspensions, gels, and digesta illustrated that LEP was able to coat the sorghum starch granules through electrostatic interaction, which promoted starch retrogradation in gels after long-term storage. AAP and TFP were found to possess ability to suppress starch crystallization in sorghum starch gels, achieved through hydrophobic interaction with starch. TFP (glucuronoxylomannan) and most AAP particles were unable to coat sorghum starch granules, although a small number of AAP particles complexed with the starch through hydrogen bonding. The interaction between sorghum starch and MPs depended on the nature of MPs and their concentration. These findings would provide fundamentals for the utilization of MPs as glycaemic controller of starch and starch-rich foods.

Effects of quercetin and Ca(OH)2 addition on gelatinization and retrogradation properties of Tartary buckwheat starch

In this study, effects of separate and synergistic addition with quercetin (Q) and Ca(OH)2 (named TBSQ, TBSCa, and TBSQCa) on gelatinization and retrogradation characteristics of Tartary buckwheat starch (TBS) were investigated. Swelling power, solubility, and paste viscosity of TBSQCa were higher than TBSQ, and lower than TBSCa, indicating that Ca(OH)2 alleviated the restriction of quercetin on TBS gelatinization, that was also confirmed by images at nanometer scale from atomic force microscope. Retrograded TBSQ, TBSCa, and TBSQCa presented lower enthalpy, relative crystallinity, and degree of order than TBS, manifesting retrogradation of TBS can be delayed by quercetin and Ca(OH)2. Morphology of SEM and texture analysis revealed that the Ca2+, Ca(OH)+, and alkaline conditions promoted the interaction among starch, quercetin and Ca(OH)2, eliminated the influence of quercetin as a rigid filler on starch, and formed higher strength gel in TBSQCa. These findings proclaimed effective action of Ca(OH)2 in quercetin-rich starch-based foods.

A comprehensive review on heat and mass transfer simulation and measurement module during the baking process

The application of computational fluid dynamics (CFD) for controlling quality boundaries in light of temperature and moisture profiling is detailed in this review. For the mapping of intricate stream design inside the baking oven and its product-based baking interaction, efficient utilization of CFD perspectives can be observed. The most crucial element in baking that affects product quality is temperature. Based on heat transfer, the CFD model proved effective in estimating the product's crumb and crust temperatures. In addition to time and temperature, the position of the dough inside the oven affects the quality of the finished product during baking. CFD demonstrating angles effectively predicts the temperature profiles inside the baked product and henceforth, assists with controlling the extreme quality of the product. Regardless, also demonstrating studies ought to be embraced including mass transport and volume extension during the baking process. A piece of the issues related to moisture and heating measures during exhibiting of bread, bun, and cookies baking process, have been included. This study exhibits CFD to be a significant tool for the simulation of the baking oven and relative expectation of temperature and moisture profiles which eventually impacts starch gelatinization and browning issue during the baking process. The mass transfer during baking and volume expansion of various bakery products can also be modelled using CFD.

Sensory and Microstructural Properties of Cakes Made with Flour from Low Postharvest Physiologically Deteriorated Cassava

The pertinent information generated from studying quality characteristics such as the structure and crumb properties of baked food products such as bread, cake etc. is very critical as it enhances product quality and inevitably help improve consumer acceptability. This research was carried out to assess the sensory qualities and investigate the microstructural properties of cakes made with high quality cassava flour (HQCF) from selected varieties of low postharvest physiologically deteriorated (PPD) cassava. Wholesome four varieties of yellow-fleshed Low PPD cassava and one variety of high PPD cassava were processed into high quality cassava flour flowing unit operations such peeling, washing, grating, pressing, pulverization and eventual drying using flash dryer operated at 120 °C for 10 minutes followed by milling with cyclone hammer mill fitted with a screen of 250 µm aperture size; the HQCF was allowed to cool, sieved and then packed into high density polyethylene bag. The cakes were analyzed for sensory and microstructural properties. Analysis of variance was performed on the data generated while significant means were separated applying Duncan Multiple Range Test using Statistical Package for Social Sciences (SPSS version 25.0). Generally, there was no significant difference (p≥0.05) in the sensory qualities (Color, texture, aroma, taste, flavor and overall acceptability) of the cakes made. The cake samples had sensory scores with ranges: (2.20 – 3.40), texture (2.60 – 4.10), aroma (2.90 – 4.20), taste (3.10 – 3.80) favor (2.90 – 3.80) and overall acceptability (2.90 – 3.70). The most preferred cake sample was C-070593 (cake sample baked with HQCF from IITA-TMS-IBA070593 cassava. Microstructural properties of cake baked with wheat flour was significantly different from cakes baked with HQCF from low PPD cassava owing to water absorption capacity, starch gelatinization characteristics and dough composition such as gluten quality. Cakes of acceptable sensorial and microstructural characteristics similar to that made with 100% wheat flour were produced with HQCF from selected varieties of low PPD cassava.

Optimization and characterization of biodegradable film based on glutinous flour/glycerol/chitosan/ZnO using Response Surface Methodology (RSM) - Central Composite Design (CCD)

Starch-based films are considered more competitive than petroleum because they are renewable, environmentally friendly, and easily degraded. The film in this study was fabricated from white glutinous flour, glycerol, chitosan, and ZnO through a starch gelatinization process. Chitosan content ranges from 2-4% (w/v), ZnO 4-8% of the dry weight of solid, and glycerol 15-45% of the dry weight of solids with a mass of white glutinous flour as much as 3 g was determined. Optimization and determination of running variables based on Central Composite Design. Response variables such as tensile strength, elongation, and water absorption were observed as important parameters in applying film as packaging materials. The Design Expert program recommended 2 g of chitosan: 8 % ZnO: 36.02% glycerol as the best composition in film fabrication, which aims to obtain maximum tensile strength and elongation, as well as minimum water absorption with the maximum desirability value (0.660). The predicted response values under optimal conditions by RSM were 3.68 MPa for tensile strength, 86.79% for elongation, and 268.09% for water absorption. The actual response has a tensile strength of 3.31 MPa, elongation of 83.5%, and water absorption of 320%. On average, a white glutinous flour/glycerol/chitosan/ZnO-based film required ± 45 days to degrade in the soil completely.

Effect of tea extract on starch gelatinisation, gluten aggregation and quality characteristics of dry yellow alkaline noodle

SummaryThree kinds of tea extracts (green tea extract, black tea extract and oolong tea extract) were incorporated into a dry yellow alkaline noodle (YAN) at a concentration of 0.5%–2.0% to investigate their effects on starch gelatinisation, gluten aggregation and noodle quality characteristics. Due to the starch–polyphenol interaction, the temperature and enthalpy required for starch gelatinisation were decreased by 0.90–1.10 °C and 2.85–3.31 J/g, respectively, when 2.0% tea extract was added compared with the control. Furthermore, the dry noodles showed lower starch pasting viscosities (reduced by 28.35%–55.20%) and increased resistance to breakdown and retrogradation. Through the hydrogen bonding between gliadins and tea polyphenols, the conformation of gluten was modified (15.41%–24.62% and 15.19%–22.95% increases in α‐helix and β‐sheet contents, respectively) and its structure was strengthened. The combined effect of tea extracts on starch gelatinisation and gluten formation behaviour resulted in the restricted water permeability and mobility in the structure of cooked noodles, which was associated with increased hardness (13.15–16.34 N), cohesiveness (0.63–0.69), chewiness (7.47–10.88) and resilience (0.34–0.42). It also decreased the absolute adhesiveness (0.11–0.13 N.sec) of cooked YANs. In the alkaline noodle system, three kinds of tea extracts exhibited similar effects on the quality characteristics of YAN. The results suggest that tea extracts are capable of improving YAN texture.

Structural and Physicochemical Properties of Starch from Rejected Chestnut: Hydrothermal and High-Pressure Processing Dependence.

The quality standards for the export of chestnuts generate large quantities of rejected fruits, which require novel processing technologies for their safe industrial utilization. This study aimed to investigate the impact of high-pressure processing (HPP) and hydrothermal treatments (HT) on the physicochemical properties of rejected chestnut starch. Chestnuts were treated by HPP at 400, 500, and 600 MPa for 5 min and HT at 50 °C for 45 min. In general, all HPP treatments did not induce starch gelatinization, and their granules preserved the integrity and Maltese-cross. Moreover, starch granules' size and resistant starch content increased with the intensity of pressure. Native and HT chestnut starches were the most susceptible to digestion. HPP treatments did not affect the C-type crystalline pattern of native starch, but the crystalline region was gradually modified to become amorphous. HPP-600 MPa treated starch showed modified pasting properties and exhibited the highest values of peak viscosity. This study demonstrates for the first time that after HPP-600 MPa treatment, a novel chestnut starch gel structure is obtained. Moreover, HPP treatments could increase the slow-digesting starch, which benefits the development of healthier products. HPP can be considered an interesting technology to obtain added-value starch from rejected chestnut fruits.

Bean softening during hydrothermal processing is greatly limited by pectin solubilization rather than protein denaturation or starch gelatinization

The rate liming step of bean softening during cooking was evaluated. Red kidney beans (fresh/non-aged and aged) were cooked at different temperatures (70–95 °C) and their texture evolution established. Softening of beans (loss of hard texture) with cooking and increasing cooking temperature was evident at ≥ 80 °C more so for non-aged than aged beans, evidencing hard-to-cook development during storage. Beans at each cooking time and temperature were subsequently classified into narrow texture ranges and bean cotyledons in the most frequent texture class evaluated for the extent of starch gelatinization, protein denaturation and pectin solubilization. During cooking, starch gelatinization was shown to precede pectin solubilization and protein denaturation, with these reactions progressing faster and to a greater extent with increasing cooking temperature. At 95 °C for instance (practical bean processing temperature), complete starch gelatinization and protein denaturation is attained earlier (∼10 and 60 min cooking, respectively and at comparable time moments for both non-aged and aged beans) than plateau bean texture (∼120 and 270 min for non-aged and aged beans)/plateau pectin solubilization. The extent of pectin solubilization in the cotyledons was consequently most correlated (negatively, r = 0.95) with and plays the most significant role (P < 0.0001) in directing the relative texture of beans during cooking. Ageing was shown to significantly retard bean softening. Protein denaturation plays a less significant role (P = 0.007) while the contribution of starch gelatinization is insignificant (P = 0.181). Thermo-solubilization of pectin in bean cotyledons is therefore the rate limiting step of bean softening towards attaining a palatable texture during cooking.

Feasibility of hydrocolloid addition for 3D printing of Qingtuan with red bean filling as a dysphagia food

Glutinous rice flour, the main component of Qingtuan, has increased adhesiveness after gelatinization and hardness after aging; this results in great challenge in swallowing if for patients with dysphagia. Dual nozzle 3D printing has great potential for developing innovative Chinese pastries with fillings that conform to dysphagia diets. In this experimental study, the gelatinization and retrogradation behavior of glutinous rice starch was improved by designing printing inks of optimal properties made with different soluble soybean polysaccharide (SSPS) additions (0%, 0.3%, 0.6%, 0.9%). The internal structure of Qingtuan was modified by adjusting different filling densities (75%, 100%) in combination with the dual nozzle 3D printing. The objective of these tests was to enhance the texture of Qingtuan so that it meets the requirements of International Dysphagia Diet Standardization Initiative (IDDSI). The experimental results showed that 0.9% SSPS addition could effectively reduce the hardness and adhesiveness of the Qingtuan, which met the Level- 6 -soft & bite-sized standard while lower filling density lowers both hardness and adhesiveness.

Acidic polysaccharides from black ear and silver ear mushrooms modulated the release and transport of glucose from gelatinised sorghum starch during digestion

This study investigated the ability of acidic polysaccharides from Auricularia auricula-judae (AAP) and Tremella fuciformis (TFP) mushrooms to modulate starch digestion and absorption. Gelatinised sorghum starch was used as starch-rich material, and its digestion and glucose transport were determined through in vitro digestion/Caco-2 cells model. Results showed that fortification with 0.6% AAP/TFP increased the proportion of high molecular weight α-dextrin and delayed glucose diffusion from digested starch gels. Gelatinisation of sorghum starch with AAP and TFP reduced the amount of transported glucose by 34.2% and 38.7%, respectively. This reduction was related to the inhibition of AAP/TFP on α-glucosidase and the difficulty in the hydrolysis of high molecular weight maltooligosaccharides. The potential bonding of AAP/TFP to glucose transporter (SGLT1) also impeded glucose transport. The findings suggest that AAP/TFP could act as natural hypoglycaemic agents used in starch-based foods and provide a better understanding of the hypoglycaemic mechanism of mushroom polysaccharides.

Improved Extrusion Cooking Technology: A Mini Review Of Starch Modification

ABSTRACT In the literature, there are several articles that worked with what they called improved extrusion cooking technology (IECT), which is an innovative machine for the modification of starch, obtained from the traditional screw extruder. This review focused on the advances in the application of the IECT used in food processing, from the perspective of the results obtained in some physicochemical properties. Interesting results have been obtained, such as significant starch gelatinization at a moisture content of 70% and a screw speed of 37 rpm. In the index of water absorption and water solubility, a variety of results are obtained, depending on the process conditions. The IECT has potential applying it not only to the modification of starch, but also comparing it with other types of extruders, with the intention of increasing and diversify the results for their potential use in food.

Properties of blends from pregelatinized starch with poly (vinyl alcohol) for hygienic-purposed disposable laundry bags

This research was focused on the properties of poly (vinyl alcohol) (PVOH) blended with pregelatinized starch (PSt) as a suitable material to make laundry bags for infected clothes application. PVOH and PSt (0, 10, 20, 30, and 40 wt.%) with glycerol 20 phr were melt-blended by twin-screw extruders. The samples were processed into the film by single layer-blown film extrusion. From the results, it was found that PVOH, glycerol, and pregelatinized starch had intermolecular interactions with each other, forming hydrogen bonding interactions between PVOH/pregelatinized starch and glycerol. The glass transition temperature (Tg) of a blend was shifted to a higher temperature by increasing the pregelatinized starch content leading to a reduction in the percent crystallinity. The presence of pregelatinized starch slightly increased the melt flow rate (MFI)/melt volume rate (MVR), apparent viscosity, and viscosity average molecular weight (Mv) of the blends due to the chain entanglement but it decreased the water solubility time and the moisture content. A co-continuous phase with small coalescence was found when 30% pregelatinized starch was added, increasing the elongation at break to 171%. On the other hand, the pregelatinized starch content was 40%, the elongation at break reduced to 154%.

Effects of five carbohydrate sources on cat diet digestibility, postprandial glucose, insulin response, and gut microbiomes.

Cat obesity has become a serious problem that affects cats' lives and welfare. Knowing how to control obesity in pet cats and its mechanism is urgently needed. Here, by feeding 30 cats different diets for 28 d, we explored the effects of 5 cat foods with potato, sweet potato, cassava, rice, and wheat as the main carbohydrate sources on the glycolipid metabolism of pet cats. The results showed that dietary carbohydrate sources did not affect the normal growth performance and stool scores of cats. Notably, we found that the starch gelatinization degree of sweet potato and cassava cat food were higher than those of other groups, while the rice diets had the highest digestibility, but the difference was not significant (P > 0.05). Furthermore, cats fed cassava diets had lower postprandial glucose responses. The mean glucose value, maximum glucose value, AUC0-360 min, AUC≤30 min, and AUC≥30 min in the cassava group were lower than those in other dietary groups (P > 0.05). In addition, we found that the carbohydrate source had a minimal effect on serum biochemical immune indices, but the blood lipid indices, such as TG, TC, HDL, and LDL of cats fed the cassava diet were maintained at a low level compared with other groups (P > 0.05). In addition, diets with different carbohydrate sources affect the gut microbial composition, and sweet potato and cassava diets tend to increase the diversity of gut microbiota with a higher Shannon index and Simpson index. The abundance of Fusobacterium, Veillonella, and Actinobacillus was significantly higher in sweet potato diet-fed cats (P < 0.05), while the abundance of Delftia, Shinella, Rothia, and Hydrogenophage was highest in cassava diet-fed cats (P < 0.05). Collectively, this study revealed that cassava and sweet potato diets have a better effect on feeding value, controlling blood glucose and blood lipids, and improving the intestinal flora of pet cats, which is worth developing dietary formulations to alleviate pet obesity.

Effects of different processing techniques of broken rice on processing quality of pellet feed, nutrient digestibility, and gut microbiota of weaned piglets.

The present study was conducted to assess the effect of different processing techniques of broken rice on processing quality of pellet feed, growth performance, nutrient digestibility, blood biochemical parameters, and fecal microbiota of weaned piglets. A total of 400 crossbred piglets (Duroc × Landrace × Yorkshire) with a mean initial body weight (BW) of 7.24 ± 0.52 kg were used in a 28-d experiment. Piglets were randomly distributed to one of 4 treatment and 10 replicate pens per treatment, with 10 piglets per pen. The dietary treatments were as follows: CON, corn as the main cereal type in the dietary; BR, 70% of the corn replaced by broken rice; ETBR, 70% of the corn replaced by extruded broken rice; EPBR, 70% of the corn replaced by expanded broken rice. Extruded broken rice and expanded broken rice supplementation significantly (P < 0.05) increased hardness, pellet durability index, crispness, and starch gelatinization degree. Extruded broken rice and expanded broken rice generated a higher (P < 0.05) average daily feed intake, increased (P < 0.05) average daily gain, decreased (P < 0.05) feed conversion ratio, and lowered (P < 0.05) the diarrhea rate. Piglets fed extruded broken rice displayed high apparent total tract digestibility levels of dry matter (P < 0.05), gross energy (P < 0.05), crude protein (P < 0.05), and organic matter (P < 0.05). In addition, extruded broken rice and expanded broken rice supplementation had increased Lactobacillus and Bifidobacterium levels in gut, whereas a lower abundance of the potential pathogens Clostridium_sensu_strictio_1 and Streptococcus was observed. Dietary supplementation of extruded broken rice and expanded broken rice failed to show significant effects on blood biochemical parameters. Combined, 70% corn substituted with broken rice failed to show significant effects. Collectively, extruded broken rice and expanded broken rice supplementation had positively enhanced the pellet quality, growth performance, nutrient digestibility, and gut microbiota of weaned piglets.

Effects of different processing techniques of palm kernel cake on processing quality of pellet feed, nutrient digestibility, and intestinal microbiota of pigs.

The present study was conducted to investigate the effects of extrusion, fermentation, and enzymolysis of palm kernel cake on processing quality of pellet feed, nutrient digestibility, and intestinal microbiota of pigs. First, the pretreatment parameters of extrusion, enzymolysis, and fermentation of palm kernel cake were optimized. Then, PKC after three processing techniques were used to prepare pellet feed. A total of 160 crossbred piglets (Duroc × Landrace × Yorkshire) with an average body weight of 28 ± 0.5 kg were used in an 8-wk feeding experiment. Pigs were randomly assigned to five treatments with four replicates per treatment and eight pigs per replicates. The five experimental groups were as follows: basal diet group (whole corn-soybean meal), 10% PKC group (PKC), 10% extrusion PKC group (PPKC), 10% enzymolysis PKC group (EPKC), and 10% fermented PKC group (FPKC), respectively. At the end of the experiment, four pigs from each treatment (randomly collected one pig per pen) were sacrificed by administering a pentobarbital overdose, the gut and blood samples were collected for the quantification analysis of microbiota, hematological parameters, and apparent total tract nutrient digestibility. The results showed that all three processing techniques significantly decreased the contents of crude fiber of PKC (P < 0.01), pulverization rate (P < 0.01), powder content (P < 0.01), and increased the hardness and gelatinization starch of pellet feed (P < 0.05) compared to PKC group. In addition, PPKC significantly improved the dry matter, crude protein, and ether extract content, blood indices and average daily feed intake compared to PKC group (P < 0.01), while the parameters were similar among FPKC, EPKC, and control group (P > 0.01). Furthermore, all three processing techniques significantly increased the Lactobacillus and decreased the Escherichia levels in feces or gut compared to PKC. Collectively, extrusion, fermentation, and enzymolysis of PKC had positively enhanced the pellet quality, growth performance, nutrient digestibility, and gut microbiota, extrusion exhibited a superior feeding effect compared to fermentation and enzymolysis.

Optimising Starch Transformation in Aquafeed Extrusion for Enhanced Water Stability and Performance

The physical quality of aquafeed pellets is paramount for the health and performance of aquatic species in aquaculture systems. Starch, a small, but necessary component of aquafeed, plays a crucial role in creating durable and water-stable pellets. This paper investigates the complex relationship between starch transformation during extrusion cooking and its influence on water stability. Through a series of experiments involving various extrusion parameters, including three melt moisture levels and three screw speeds, the study reveals that the key to producing water-stable aquafeed lies in optimizing starch gelatinization and minimizing dextrinization. High screw speeds, in conjunction with moderate to high melt moisture levels, facilitate starch gelatinization while avoiding dextrinization, resulting in pellets with superior water stability. Conversely, low melt moisture levels at any screw speed or any melt moisture at low screw speeds lead to poor water stability due to increased dextrinization or suboptimal gelatinization levels. The research also underscores the critical role of the glass transition of starch. Starch in its semi-crystalline state is found to be more susceptible to shear degradation during extrusion. Therefore, rapidly elevating the raw material's temperature above its glass transition temperature is crucial for achieving water-stable aquafeed.