Hot Paste Viscosity Research Articles

Rheological, Thermal and Physicochemical Properties of Bioprocessed Flour From Cowpea, Sorghum and Orange Fleshed Sweet Potato

ABSTRACTThis study investigated the rheological, physicochemical, and thermal properties of fermented and germinated whole reddish‐brown cowpea, white sorghum and orange‐fleshed sweet potato. Germination substantially reduced the pasting and rheological attributes of flour suspensions compared to the fermentation process. This study observed notable increases in the hot paste, setback, and final viscosities after the fermentation of cowpea and sorghum, indicating an improvement in the ease of cooking and greater retrogradation tendency of starch molecules. Among the fermented flours, sorghum had the highest hot paste viscosity (848 mPa s) and final viscosity (1451 mPa s). The mechanical fingerprint revealed a viscoelastic solid character, with G′ > G″ over the frequency range of 0–10 rad/s for all samples. Temperature sweep data showed a sharp increase in G′ at about 80°C, corresponding to the onset of starch gelatinization. Shear‐thinning behavior was observed, except in germinated and raw sorghum flours, where molecular rearrangement resulted in an initial viscosity rise at a low share rate (< 20 s−1). Differential scanning calorimetric analysis revealed a marginal variation in the peak transition temperature of gelatinization (98°C–104°C for all flours except raw sorghum flour, 83.87°C). The fermented sweet potato flour indicated good flour particle flowability expressed as Carr's compressibility index (30.99) and the Hausner ratio (1.45); however, the available reducing sugars could have influenced its high percentage solubility (49.83%), thus impacting low pasting viscosities. The contrasting technological features suggest an avenue to intensify efforts in exploring composite bioprocessed flours for applications in novel foods.

Impact of Ferulated Arabinoxylans from Maize Bran on Farinograph and Pasting Properties of Wheat Flour Blends.

This research explores the extraction of ferulated arabinoxylans (FAXs) from maize bran and their incorporation into wheat flour to assess their impact on rheological and pasting properties. Flour blends were prepared with FAX concentrations of 0%, 2%, 4%, 6%, 8%, and 10%, and these blends were then evaluated using farinograph, mixograph, micro-extensibility, and viscosity analyses. The results indicated that farinograph water absorption increased significantly (p ≤ 0.05), ranging from 54.9% to 60.5%, as the FAX content rose, correlating with higher gel-forming potential. Notably, the 2% FAX treatment (FAX2) exhibited the longest dough development time at 24.7 min. Stability and mixing time index (MTI) values also varied significantly (p ≤ 0.05) among treatments, with FAX2 displaying a longer mixing time of 14.4 ± 3.3 min. A pasting analysis revealed a significant decrease in peak and hot paste viscosity (p < 0.05) with increasing FAX concentrations, suggesting an association between lower hot paste viscosity and reduced breakdown. Micro-extensibility measures further indicated that blends with 0% and 2% FAX had greater extensibility, while the 4% FAX blend showed higher resistance. Overall, this research aims to advance the understanding of how these components can enhance flour functionality and contribute to the development of healthier, higher-quality baked products.

Responses of rice qualities to temperature and light in three different ecological environments in karst regions

Rice cultivation in Karst regions shows significant variations in both yield and quality due to temperature and light. Herein, 241 varieties including 198 indica rice and 43 japonica rice were planted in three ecological regions to investigate responses of rice qualities to meteorological factors. Results showed that in regions with higher average temperature (25.43 °C) and less daily sunshine hour (2.53 h/day), the appearance qualities (chalkiness degree, chalkiness rate and size) and processing qualities (brown rice percentage, head rice and milled rice percentages) were significantly reduced (p < 0.05). A total of 723 samples in three ecological environments were grouped into 4 clusters, arranged in descending order of cluster scores. In high-scoring cluster, the processing quality, appearance quality, protein content, hot paste viscosity, consistence viscosity, and setback viscosity were negatively correlated with temperatures (average temperature, temperature difference, effective accumulated temperature, maximum and minimum temperatures) from heading to mature stages, but positively correlated with sunshine hours. Apparent amylose contents were negatively correlated with temperatures but not significantly correlated with sunshine hours. In low-scoring cluster, only the processing quality had significant correlations with meteorological factors. These findings revealed the interaction between temperature and light for the formation of rice quality.

Technological Properties of Tritordeum Starch

Tritordeum is a new promising cereal derived from wild barley and cultivated durum wheat; such a combination allowed for the transfer of some useful barley traits to the resulting hybrid. In the future, the importance of this cereal can increase, becoming a raw material for the production of various products, including starch. So far, tritordeum starch has attracted little interest from researchers, and therefore, an attempt was undertaken to investigate its properties. Its morphological features, chemical composition, thermal and pasting properties, particle size, and retrogradation kinetics were investigated. These properties were compared to other cereal starches. Tritordeum starch granules resembled wheat starch in shape, and they were characterized by a relatively small size and the highest lipid and non-starch material content among the investigated starches. Tritordeum starch’s pasting profile showed a unique character, resulting in high pasting temperature and low, but stable, hot paste viscosity. Also, its rate of retrogradation was the lowest, probably due to the high lipid content, and the retrogradation extent was restricted.

Changes in the pasting and rheological properties of wheat, corn, water caltrop and lotus rhizome starches by the addition of Annona montana mucilage

Annona montana mucilage (AMM) is a novel mucilage with unique but limited information. This study investigated the effects of AMM addition on the pasting and rheological properties of wheat starch (WS), corn starch (CS), water caltrop starch (WCS), and lotus rhizome starch (LRS). The addition of AMM generally increased the pasting temperature and peak viscosity, but reduced the setback value of all starches to varying degrees, and the initiation of viscosity-increase for cereal starch/AMM systems during pasting occurred at lower temperatures, accompanied with a distinctive two-stage swelling process as well as lower peak and final hot paste viscosity at 50 °C. AMM significantly increased the pseudoplasticity and entanglement of the systems to varying degrees (LRS > WS > WCS > CS). Under a constant shear rate of 50 s−1, the consistency level was found to fall in honey-like for cereal starch/AMM groups, and honey-like to extremely thick levels for WCS and LRS/AMM groups. Except for the WCS/AMM systems, the storage and loss modulus as well as tanδ increased with increasing AMM concentration. Short-term retrogradation of starch at 4 °C was pronouncedly retarded by the addition of AMM for WS, CS and WCS groups, but was less affected for LRS group.

Can a delayed sowing date improve the eating and cooking quality of mechanically transplanted rice in the Sichuan basin?

Adjustment of the sowing date is a widely used measure in rice production to adapt to high-temperature conditions. However, the impact of delayed sowing date (DS) on rice quality may vary by variety and ecological conditions. In this study, we conducted experiments using different sowing dates, that is, conventional sowing date 1 (CS1), CS2 (10 d later than CS1), DS1 (30 d later than CS1), and DS2 (30 d later than CS2), and three rice varieties, i.e., “Yixiangyou 2115,” “Fyou 498,” and “Chuanyou 6203.” This experiment was conducted at four sites in the Sichuan basin in 2018 and 2019 to evaluate the influence of DS on the pasting properties of rice, which are a proxy for eating and cooking quality (ECQ). In DS1 and DS2, rice had a significantly greater amylose content (AC) but a lower protein content (PC), peak viscosity (PKV), cool paste viscosity (CPV), and hot paste viscosity (HPV) than in CS1 and CS2. Moreover, with the exception of CS2 and DS1 in 2018, DS1 and DS2 led to a 2.15–11.19% reduction in breakdown viscosity (BDV) and a 23.46–108.47% increase in setback viscosity (SBV). However, the influence of DS on rice pasting properties varied by study site and rice variety. In 2019, DS1 and DS2 led to a BDV reduction of 2.35–9.33, 2.61–8.61, 10.03–17.78, and 2.06–8.93%, and a SBV increase of 2.32–60.93, 63.74–144.24, 55.46–91.63, and -8.28–65.37% at the Dayi, Anzhou, Nanbu, and Shehong, respectively. DS resulted in a greater decrease in PKV, HPV, CPV, and BDV and a greater increase in the AC and SBV for Yixiangyou 2115 than for Chuanyou 6203 and Fyou 498. Correlation analysis indicated that PKV and HPV were significantly and positively related to the mean, maximum, and minimum temperatures after heading. These temperatures have to be greater than 25.9, 31.2, and 22.3℃ to increase the relative BDV and decrease the relative SBV of rice, thereby enhancing ECQ. In conclusion, DS might contribute to a significant deterioration in ECQ in machine-transplanted rice in the Sichuan basin. A mean temperature above 25.9℃ after heading is required to improve the ECQ of rice.

Genome-Wide Association Study of Cooked Rice Textural Attributes and Starch Physicochemical Properties in indica Rice

Rice cooking and eating qualities (CEQ) are mainly determined by cooked rice textural parameters and starch physicochemical properties. However, the genetic bases of grain texture and starch properties in rice have not been fully understood. We conducted a genome-wide association study for apparent amylose content (AAC), starch pasting viscosities, and cooked rice textural parameters using 279 indica rice accessions from the 3 000 Rice Genome Project. We identified 26 QTLs in the whole population and detected single nucleotide polymorphisms (SNPs) with the lowest P-value at the Waxy (Wx) locus for all traits except pasting temperature and cohesiveness. Additionally, we detected significant SNPs at the SUBSTANDARD STARCH GRAIN6 (SSG6) locus for AAC, setback (SB), hardness, adhesiveness, chewiness (CHEW), gumminess (GUM), and resilience. We subsequently divided the population using a SNP adjacent to the Waxy locus, and identified 23 QTLs and 12 QTLs in two sub-panels, WxT and WxA, respectively. In these sub-panels, SSG6 was also identified to be associated with pasting parameters, including peak viscosity, hot paste viscosity, cold paste viscosity, and consistency viscosity. Furthermore, a candidate gene encoding monosaccharide transporter 5 (OsMST5) was identified to be associated with AAC, breakdown, SB, CHEW, and GUM. In total, 39 QTLs were co-localized with known genes or previously reported QTLs. These identified genes and QTLs provide valuable information for genetic manipulation to improve rice CEQ.

Technological, quality and nutritional characteristics of Ramen noodles with wheat flour partially substituted by water chestnut flour

Ramen noodles were prepared by partially supplementing traditional wheat flour with water chestnut flour (WCF) at 30, 40 and 50% levels w/w. The composition, pasting and farinograph indices of flour blends were studied. Noodles were analysed for colour, radical scavenging and functional characteristics. Time for dough development, stability and farinograph quality number declined significantly from 5.250±0.07 to 1.20±0.01 min, 6.45±0.07 to 1.31±0.01 min and 81.50±0.71 to 18.50±0.71, respectively, after replacement. Statistically significant increment in pasting temperature (60.91±0.01 to 72.05±0.07°C), peak viscosity (1094.05±0.07 to 1099.25±0.35 Brabender Unit, BU), breakdown (310.05±0.07 to 376.05±0.07 BU), hot paste (782.05±0.07 to 996.10±0.14 BU) and cold paste viscosities (1548.10±0.14 to 1701.25±0.35 BU) were found with the addition of WCF. Non-traditional ramen exhibited significantly improved fibre, antioxidant potential and mineral content with significant reduction in % fat and caloric count. The colour variation data in ramen noodles were: L* (66.35–57.86); a* (0.24–2.08); and b* (4.03–4.47). Texture hedonic scores varied between 8.38 and 7.57 with chestnut flour level increment. Hardness of Ramen noodles samples ranged between 13.9 and 19.8 N.

Effect of addition of methionine and histidine on physicochemical and rheological characteristics of water chestnut starch as revealed by molecular dynamic simulations

The effect of addition of amino acids including methionine (Met) and histidine (His) at selected concentrations (2, 6, 10, and 15%) on the physicochemical, pasting, and rheological properties of water chestnut starch (WS) was evaluated. A higher quantity of amino acids considerably (p < 0.05) inhibited the ability of starch-amino acid blends to expand their solubility index and swelling capacity. The addition of amino acids also significantly decreased peak viscosity (952.33–540.67 cP), hot paste viscosity (917–528 cP), cold paste viscosity (1209.67–659 cP), and setback (277.67–131 cP) of WS. Addition of amino acids enhanced the stability ratio (SR) of WS. All the studied samples displayed storage moduli (G′) values higher than loss moduli (G′′) but rheologically weak gel characteristics. Molecular dynamics simulation studies revealed that interactions between amino acids and water greatly reduced the number of starch–water hydrogen bonds while preserving a higher number of starch-starch intramolecular interactions. This study could provide important insights for better understanding of modification of water chestnut starch functionality under the influence of amino acid residues.

A new source of starchy flour: Physicochemical and nutritional properties of starchy kiwifruit flour

The physicochemical and nutritional properties of three starchy kiwifruit flour (SKF) were systematically studied. The results revealed that the total starch content of SKF was 66.63–80.42%. SKF showed a B-type crystal structure with a grain size between 7.08 and 9.02 μm. In comparison to corn starch and potato starch, SKF possessed a lower pH (3.43–4.28), transparency (0.68–1.11%) and setback value (0.20–1.73 Pa·s) and a higher swelling power (9.42–15.02 g/g) and hot paste viscosity (1.73–2.10 Pa·s). Moreover, SFK was rich in protein and various mineral elements. It also contained high levels of total phenolics and exhibited a strong antioxidant capacity. The resistant starch content in SKF was as high as 67.19–73.22%, and the rapidly digestible starch content was remarkably lower than that of corn and potato starch. Overall, these unique physicochemical properties of SKF, coupled with its nutritional benefits, give it a good development potential in the food industry.

Modulation of the retrogradation kinetics of sweet potato starch by the addition of pectin, guar gum, and gallic acid

The effects of the addition of pectin (P), guar gum (GG), and gallic acid (GA) on the pasting properties and retrogradation kinetics of sweet potato starch (SPS) during storage at 4 °C were evaluated by whiteness, as a measure of turbidity, molecular mobility, and differential scanning calorimetry analysis. The incorporation of GG increased the peak, hot paste, breakdown, and final viscosities of the systems, while the opposite resulted with the addition of P and GA. Gallic acid was particularly effective in delaying the progress of SPS retrogradation, since lower whiteness and retrogradation degree and kinetic parameters were obtained throughout the storage assay. Proton population and relaxation times analysis confirmed higher water molecules retention in the presence of GA, which limited hydration and swelling of SPS, thus reducing its posterior retrogradation. Besides, its low molecular weight and high polarity could have hindered starch molecules' reassociation through non-covalent interactions. A concentration-related effect was observed for P, since 1% addition delayed retrogradation, but it was accelerated when 2% were added due to changes in inter and intramolecular interactions between pectin and SPS. Finally, GG promoted SPS retrogradation, which could be explained by the breakage of the structure of swollen starch granules that facilitated ulterior reorganization. Results confirmed that SPS retrogradation can be successfully modulated by the incorporation of pectin, guar gum, or gallic acid for different gluten-free industrial applications.

Grain quality characteristics analysis and application on breeding of Yuenongsimiao, a high-yielding and disease-resistant rice variety

Rice quality is one of the main targets of rice breeding and is a complex trait that involves grain appearance, milling, cooking, eating and nutritional quality. For many years, rice breeding has contended with imbalances in rice yield, quality, and disease and lodging resistance. Here, the milling and appearance quality, cooking quality, starch rapid viscosity analyzer (RVA) profile, and nutritional quality of grains of Yuenongsimiao (YNSM), an indica rice variety with high yield, high quality and disease resistance, were determined. YNSM had excellent appearance and quality, with low amylose contents and high gel consistency, and these characteristics exhibited significant correlations with the RVA profile such as hot paste viscosity, cool paste viscosity, setback viscosity, and consistency. Moreover, 5 genes related to length-to-width ratio (LWR) as well as the Wx gene were used to detect the main quality genotype of YNSM. The results showed that YNSM is a semilong-grain rice with a relatively high brown rice rate, milled rice rate and head rice yield and low chalkiness. The results indicated that the LWR and food quality of YNSM might be related to gs3, gw7 and Wxb. This study also reports the quality characteristics of hybrid rice developed using YNSM as a restorer line. The quality characteristics and the genotype for grain quality determined through gene analysis in YNSM may facilitate the breeding of new rice varieties that achieve a balance of grain yield, resistance and quality.

Research on the Relationship between the Amylopectin Structure and the Physicochemical Properties of Starch Extracted from Glutinous Rice.

Glutinous rice has very low amylose content and is a good material for determining the structure and physicochemical properties of amylopectin. We selected 29 glutinous rice varieties and determined the amylopectin structure by high-performance anion exchange chromatography with the pulsed amperometric detection method. We also determined the correlation between amylopectin structure and the physicochemical properties of starch extracted from these varieties. The results showed that the amylopectin chain ratio Σdegree of polymerization (DP) ≤ 11/ΣDP ≤ 24 of 29 glutinous rice varieties was greater than 0.26, signifying that these varieties contained type II amylopectin. The results of the correlation analysis with gelatinization temperature showed that ΣDP 6-11 was significantly negatively correlated with the onset gelatinization temperature (GT) (TO), peak GT (TP), and conclusion GT (TC). Among the thermodynamic properties, ΣDP 12-24 was significantly positively correlated with To, Tp, and Tc, ΣDP 25-36 was significantly negatively correlated with To, Tp, and Tc, and ΣDP ≥ 37 had no correlation with the thermodynamic properties. The results of correlation analysis with RVA spectrum characteristic values showed that ΣDP 6-11 was significantly negatively correlated with hot paste viscosity (HPV), cool paste viscosity (CPV), consistency viscosity (CSV), peak time (PeT), and pasting temperature (PaT) among the Rapid Visco Analyzer (RVA) profile characteristics, ΣDP 12-24 was significantly positively correlated with HPV, CPV, CSV, PeT, and PaT, and ΣDP ≥ 25 had no correlation with the viscosity characteristics. Therefore, we concluded that the amylopectin structure had a greater effect on the TO, TP, TC, ΔH and peak viscosity, HPV, CPV, CSV, PeT, and PaT. The glutinous rice varieties with a higher distribution of short chains and a lower distribution of medium and long chains in the amylopectin structure resulted in lower GT and RVA spectrum characteristic values.

Variation in starch physicochemical properties of rice with different genic allele combinations in two environments

The starch physicochemical properties were investigated in 16 different rice accessions with different combinations of Wx, SSIIa and FLO2 alleles harvested in two environments. FLO2, Wx and SSIIa alleles and their interaction significantly affected the starch properties. The values of apparent amylose content (AAC), gel hardness (HD), pasting temperature (PT), gelatinization temperature (GT), enthalpy of gelatinization (ΔHg), enthalpy of retrogradation (ΔHr) and percentage of retrogradation (R%) in the rice with FLO2 allele were slightly larger than those with flo2 mutant allele. The Wx × SSIIa interaction had a significant effect on breakdown (BD), setback (SB), ΔHr and R%. With Wxb allele, the influence of SSIIa allele on GT was slightly greater than that with Wxa. With SSIIa GC allele, Wxb played a greater role in the increase of PT than Wxa, but the reverse was found with SSIIa TT allele. The FLO2 × Wx interaction significantly affected the AAC, cold paste viscosity (CPV), hot paste viscosity (HPV), PT, HD, peak temperature (Tp), conclusion temperature (Tc) and ΔHr. FLO2 × SSIIa combination significantly affected AAC, HPV, CPV, Tc and ΔHr. This study will help us to further understand the roles of these starch synthesis-related important genes in regulating rice quality and could be better utilized in molecular breeding.

Combined Effects of Different Alleles of FLO2, Wx and SSIIa on the Cooking and Eating Quality of Rice.

The improvement of the cooking and eating quality (CEQ) of rice is one of the major objectives of current rice-breeding programs. A few major genes such as Waxy (Wx) and starch synthase IIa (SSIIa) have been successfully applied in molecular breeding. However, their interactive effects on CEQ have not been fully understood. In this study, a recombinant inbred line (RIL) population was constructed by crossing the white-core mutant GM645 with the transparent phenotype of the japonica rice variety Tainung 67 (TN67). GM645 and TN67 contain different alleles of FLOURY ENDOSPERM2 (FLO2), Wx, and SSIIa. The effects of different allele combinations of FLO2, Wx, and SSIIa on the CEQ of rice were investigated. The inbred lines with the mutation allele flo2 had a significantly lower apparent amylose content (AAC), viscosity characteristics except for setback (SB), and gel texture properties compared to those lines with the FLO2 allele. The allelic combination of FLO2 and Wx significantly affected the AAC, breakdown (BD), and gel textural properties, which could explain most of the variations in those rice quality traits that were correlated with AAC. The allelic combination of FLO2 and SSIIa significantly affected the hot paste viscosity (HPV) and pasting temperature (PT). The Wx × SSIIa interaction had a significant effect on the PT. The interaction of FLO2, Wx and SSIIa significantly affected the AAC, cold paste viscosity (CPV), PT, and consistency viscosity (CS). These results highlight the important roles of these quality-related genes in regulating the CEQ of rice and provide new clues for rice-quality improvement by marker-assisted selection.

Physicochemical, Pasting Properties and In Vitro Starch Digestion of Chinese Yam Flours as Affected by Microwave Freeze-Drying.

Microwave freeze-drying (MFD) is a new freeze-drying technique, which differs from single microwave treatment; it involves simultaneous effects of microwave power, time, and the moisture state applied to the materials. In this study, the effects of MFD under various microwave power densities (0.5, 1.0, and 1.5 W/g) on the drying characteristics of Chinese yam slices and the physicochemical, pasting, and thermal properties as well as the starch digestibility of the flour were investigated using conventional hot air drying (HAD) at 50 °C as a control. Compared to HAD, MFD shortened the drying time up to 14.29~35.71%, with a higher drying efficiency at a high microwave power density (1.5 W/g). MFD yam flours provided benefits over HAD products in terms of color, water/oil absorption capacity, and solubility, exhibiting high hot-paste viscosity but low resistant starch content. The content of total starch and free glucose of the yam flour and its iodine blue value were significantly influenced by the drying method and the MFD process parameters (p < 0.05). MFD processing could disrupt the short-range ordered structure of yam starch. Among the MFD flours, samples dried by MFD at 1.5 W/g presented the highest ratio of peak intensity at 1047 and 1022 cm−1 (R1047/1022) value, gelatinization enthalpy, and resistant starch content. These results gave a theoretical foundation for the novel freeze-drying method that MFD applied to foods with a high starch content, enabling the production of a product with the desired quality.

Physicochemical, Nutritional, and Antioxidant Properties in Seven Sweet Potato Flours.

Sweet potato flour is a key ingredient for the production of new food products worldwide, which imparts desired properties, nutritional value, antioxidants, and natural color to processed foods. However, little information regarding the functional properties of the sweet potato flour is available. In this study, the genetic diversity in the physiochemical, nutritional, and antioxidant properties of wholemeal flour from seven sweet potato varieties was investigated. The total phenolic content (TPC) of the free and bound fractions ranged from 13.85 to 90.74 mg gallic acid equivalent (GAE)/100 g and from 5.07 to 24.29 mg GAE/100 g, respectively. The average protein content of sweet potato was 5.41 g/100 g ranging from 3.40 to 8.60 g/100 g DW. The total amino acid content averaged 45.13 mg/g DW. The average contents of 12 mineral elements were in the order of K > P > Ca > Mg > Mn > Fe > Zn > Cu > Ni > Se > Cr > Cd. K and P contents were the highest among all accessions, which were positively correlated with most of the other minerals. The average starch content of sweet potato was 53.90 g/100 g DW, ranging from 31.68 to 64.90%. The peak viscosity (PV), hot paste viscosity (HPV), and cold paste viscosity (CPV) were in the range of 90.7–318.8 Rapid Visco Unit (RVU), 77.3–208.3 RVU, and 102.6–272.7 RVU, respectively. The hardness values and cohesiveness (Coh) varied among different sweet potatoes, with a range of 8.20–18.48 g and 0.22–0.68, respectively. The gelatinization onset, peak, conclusion temperatures, and enthalpy were in the ranges of 59.39–71.91°C, 70.19–88.40°C, 78.98–95.79°C, 1.85–5.65 J/g, respectively.

Research progress on properties of pre-gelatinized starch and its application in wheat flour products

Starch is the most abundant organic compound in nature, second only to cellulose. However, the conserved structure of native starches limits their properties and applications. Therefore, it is often necessary to modify them to obtain specific properties. As a common green and safe physical modification method, pre-gelatinization can improve the cold water solubility and swelling power of starch. The typical preparation methods of pre-gelatinized starch include spray drying, extrusion, and drum drying. Spray-dried pre-gelatinized starch still had good granule shape, but the increase of cold water solubility and cold paste viscosity was relatively small. Extruded and drum-dried pre-gelatinized starch showed serious structure destruction, significant increases in cold water solubility and cold paste viscosity, but relatively low hot paste viscosity. The properties of pre-gelatinized starch obtained by different methods are different, so do their effects on the quality of flour products. Wheat flour products, as one of the leading staple food for the people all over the world, play a vital role in people's daily life. With the improvement of people's living standards, more and more special flour products with unique features have received attentions of consumers and researchers. However, the sensory characteristics of special flour products are often inferior to traditional flour products, which limits its development. The unique functional characteristics of pre-gelatinized starch make it expected to play an essential role in the quality improvement of featured flour products. In this paper, the granule morphology, crystal structure, hydration and gelatinization properties of pre-gelatinized starch prepared by three common methods and their application in flour products were reviewed, which provides a theoretical basis for the application of pre-gelatinized starch in food industry. The conserved structure of native starches limits their properties and applications. Pre-gelatinized starch prepared by spray drying, extrusion and drum drying, its structure and physicochemical properties changed significantly. Spray-dried pre-gelatinized starch still had good granule shape, but the increase of cold water solubility and cold paste viscosity was relatively small. Extruded and drum-dried pre-gelatinized starch showed serious structure destruction, significant increases in cold water solubility and cold paste viscosity. Due to its good hydration properties in cold water, it has a good application prospect in multi-grain flour products, frozen dough, gluten-free flour products and high-moisture bread.

EFFECT OF EXTRUSION PROCESS ON PERFORMANCE OF AN INDIGENOUS EXTRUDER AND QUALITY OF CASSAVA PRODUCTS

A locally developed autogenous single screw extruder was used to investigate the process for screw extrusion of the flour and starch of cassava, in a bid to find alternate uses for the commodity. The experiment was conducted with a factorial design and completely randomized. Analysis of Variance and Tukey Honestly Significant Difference methods were utilized as follow up test to check the result of extrusion variables: feed moisture (25, 30, 40%) and extruder temperature built up by varying the duration of sampling (2, 10, 18, 24, 30 minutes) on some product quality attributes and system parameters. The product quality attributes considered include water absorption index (WAI) and water solubility index (WSI), product moisture (PQ_MC), transverse expansion (ExR), cold and hot paste viscosities (CPV and HPV), Melt viscosity (MV) and strength properties of extrudates (CP) while the system parameters are product temperature (PT), mean residence time (MRT), and specific energy input (SME). All system parameters PT, MRT and SME varied directly with duration of operation. Also, PQ_MC, CP, WAI, WSI, MV, CPV and HPV varied reciprocally whereas ExR, and MV varied directly with duration of operation. The extrudates’ water loss is directly proportional with ExR. It was observed that extruded cassava starch was less stable than cassava flour extrudates. Moreover, the specific end uses to which the extruded products can be put were identified. All the treatments and their interactions are highly significant (P ≤ 0.001).

Pengaruh konsentrasi Ca(OH)2 dan suhu pemasakan pada proses nikstamalisasi tepung jagung

Nixtamalization is a corn cooking process with the addition of calcium hydroxide. This study aims to determine the best treatment combination between the concentration of Ca(OH)2 and cooking temperature to changes in physicochemical properties and amylographic properties of cornflour. This research was conducted using a completely randomized design with a factorial pattern with two factors. Factor I: concentration of Ca(OH)2 1%, 2% and 3% (w/v); Factor II: cooking temperature 70️℃, 80️℃, 90️℃, and 100️℃. The results of data analysis using ANOVA for all parameters showed significant differences. The results showed that the best treatment combination was the nixtamalization treatment with a concentration of Ca(OH)2 2% and a cooking temperature of 90️℃ which produces cornflour with a color coordinate value L*; a*; b* is 68.64; 16.27; 45.22; calcium content 0.473%; amylose content 68.92%; swelling power 7.13 ml/g; freeze-thaw stability 0.211 g/g. The microscopic structure of the best treatment showed that the surface shape of the starch granules was slightly rough, the cell walls were slightly thicker than the control corn flour; amylographic properties showed gelatinization temperature of 78.15️℃; peak gelatinization time of 8.13 minutes; peak viscosity 1147 cP; hot paste viscosity 1056 cP; breakdown viscosity 91 cP; final viscosity 2132 cP; setback viscosity 1076 cP.