Fermented Rice Noodles Research Articles

Further Interpretation of the Volatile, Microbial Community and Edible Quality of Fresh Fermented Rice Noodles with Different Selected Strains.

Understanding bacteria and yeasts can reduce unpredictable changes in fresh fermented rice noodles (FFRN). The effects of selected strains (Limosilactobacillus fermentum, Lactoplantibacillus plantarum, Lactococcus lactis and Saccharomyces cerevisiae) on the edible quality, microbial community, and volatile component of FFRN were studied. The results indicated that the fermentation time could be shortened to 12 h when Limosilactobacillus fermentum, Lactoplantibacillus plantarum, and Lactococcus lactis were added, whereas it still required approximately 42 h after adding Saccharomyces cerevisiae. Only a steady bacterial composition was provided by adding Limosilactobacillus fermentum, Lactoplantibacillus plantarum, and Lactococcus lactis, and only a steady fungal composition was provided by adding Saccharomyces cerevisiae. Therefore, these microbial results indicated that the selected single strains cannot improve the safety of FFRN. However, the cooking loss was decreased from 3.11 ± 0.11 to 2.66 ± 0.13 and the hardness of FFRN was increased from 1186 ± 178 to 1980 ± 207 when it was fermented with single strains. Finally, a total of 42 volatile components were determined by Gas chromatography-ion Mobility Spectrometry and 8 aldehydes, 2 ketones, and 1 alcohol were added during the entire fermentation process. The main volatile components were different during fermentation depending on the added strain, and there was the greatest variety of volatiles in the group with added Saccharomyces cerevisiae.

Effect of sodium bicarbonate on the physicochemical properties of fermented rice flour and quality characteristics of fermented semi-dried rice noodles.

Considering the effect that fermentation can improve the quality of rice noodles, and given that fermented rice noodles usually have a significantly acidic taste that is not generally acceptable to consumers, this study aimed to neutralize or eliminate the acidic taste of fermented rice noodles by adding sodium bicarbonate, and improve the quality of fermented rice noodles. The physicochemical properties of fermented rice flour and quality characteristics of fermented semi-dried rice noodles were investigated in this study in relation to the addition of sodium bicarbonate (0∼0.5%, w/w). With the increase of sodium bicarbonate addition, the pH value was increased, and lipid and protein content were decreased in rice flour. Meanwhile, thermal properties and farinograph properties showed that the pasting temperature, dough water absorption, dough development time and dough stability time of rice flour increased with the addition of sodium bicarbonate. Pasting properties and rheological properties results showed that a small amount of sodium bicarbonate (0∼0.1%) could increase the pasting viscosity, storage modulus (G'), and loss modulus (G″) of rice flour. Additionally, the hardness and chewiness of semi-dried rice noodles increased with the addition of sodium bicarbonate from 0 to 0.1%. With the addition of a small amount of sodium bicarbonate (0∼0.1%), x-ray diffraction showed that it could increase the crystallinity of semi-dried rice noodles. Low-field nuclear magnetic resonance showed that A21 increased, and A22 and A23 decreased in semi-dried rice noodles. Scanning electron microscope showed that it could enhance the starch-protein interaction and starch-protein formed an ordered and stable network structure. Finally, the principal component analysis showed that the chewiness, texture and eating quality of semi-dried rice noodles were the best with the addition of sodium bicarbonate at 0.1%. This study provides practical value for the application of alkali treatment in rice products and provides a reference for the improvement of related rice noodles products.

Effects of water, guar gum, potassium chloride, and drying methods on quality and rehydration time of instant fermented rice noodles

SummaryQuick rehydration is the most important characteristic of instant noodles. This study investigated the effects of ingredients on the production and drying methods, the quality, and the rehydration time of instant fermented rice noodles. The dried fermented rice flour was mixed with different amounts of water (80%, 85%, and 90%), guar gum (0.5%, 1.0%, and 1.5%), and potassium chloride (1%, 2%, and 3%). The noodles were dried in a microwave vacuum oven and compared with drying in a hot air oven and a microwave continuous oven. The optimum contents of water, guar gum, and potassium chloride were 80%, 1.5%, and 2%, respectively, because water at 80% resulted in the shortest rehydration time and the highest firmness, guar gum at 1.5% could increase firmness and the water absorption ability to produce the highest cooking yield and firmness with the lowest cooking loss, and potassium chloride at 2% resulted in the shortest rehydration time. Microwave vacuum drying produced the fastest rehydration in hot water for 2 min and the quality of these rehydrated noodles was better than for the other tested drying methods. Microwave vacuum drying generated rapid heat that promoted flash evaporation of the vapour in the noodles, resulting in a porous structure.

Consumers' emotional responses evoked by fermented rice noodles containing crickets and/or mango peel: impact of product information and prior insect consumption

SummaryExpected sensory liking and emotional profiles of three fermented rice noodles containing cricket (P‐cp), mango peel (P‐mp) and a combination of cricket and mango peel (P‐cp*mp) were virtually evaluated using an online survey (n = 727 consumers). Data were grouped by consumers as follows: consumers, who had consumed cricket, participating in the online survey before (C‐eb) or after (C‐ea) receiving product information; and consumers, who had never consumed cricket, participating in the online survey before (C‐nb) or after (C‐na) receiving product information. Expected overall sensory liking and emotional profiles were analysed using ANOVA and Correspondence Analysis, respectively. C‐ea rated all products with the highest expected sensory liking scores. P‐cp and P‐cp*mp evoked more negative emotions than did P‐mp. Consumers who did not receive information and/or those who never consumed crickets mainly expressed negative emotions. More specifically, C‐ea mostly exhibited positive emotions, whereas C‐na elicited more negative emotions for all products. This study concluded that consumers' expected sensory liking and emotional profiles of fermented rice noodles containing cricket (P‐cp) were influenced by additional product information and prior cricket consumption experience. This finding would be useful for introduction of products containing cricket.

Edible qualities, microbial compositions and volatile compounds in fresh fermented rice noodles fermented with different starter cultures

To shorten the fermentation time and reduce the heterozygous bacteria contamination during fresh fermented rice noodles (FFRNs) fermentation, four starter cultures that consist of Limosilactobacillus fermentum, Lactoplantibacillus plantarum and Saccharomyces cerevisiae were used to produce FFRN. The cooking qualities and texture profiles of FFRNs, the dynamics of microbial diversities and volatile compounds at different fermentation stages were explored. Results showed that the fermentation time of the adding starter culture groups required 12 h, while that the natural fermentation (NF) group required 36 h. Significant differences were observed in the texture profiles and cooking qualities of these five groups FFRNs (P ＜ 0.05). In addition, compared with NF group, the microbial diversity of four adding starter culture groups was significantly lower, which meant that the edible safety of FFRNs could be enhanced. Meanwhile, a total of 115 volatile compounds were detected by Gas chromatography-ion Mobility Spectrometry and Gas chromatography-mass spectrometry, the aldehydes, alcohols, acids and esters were increased while aldehydes were decreased in FFRNs during fermentation. Among these, the relative odor activity value of 50 volatile compounds was greater than 0.1, contributing unique flavors to FFRNs. Notably, the flavor of Lactoplantibacillus plantarum + Saccharomyces cerevisiae (L.p + S.c) and Lactoplantibacillus plantarum + Limosilactobacillus fermentum + Saccharomyces cerevisiae (L.pf + S.c) groups was richer than that of other groups.

Effect of Levilactobacillus brevis TISTR 860 and Lactiplantibacillus plantarum TISTR 951 on gamma‐aminobutyric acid content in fermented rice flour and rice noodles (Kanomjeen)

SummaryThis research aimed to reduce the fermentation time of fermented rice flour for fermented rice noodles (Kanomjeen) to 24 h by adding the initial starter cultures, which are Levilactobacillus brevis TISTR 860 (LB) and Lactiplantibacillus plantarum TISTR 951 (LP) alone in rice slurry to achieve the quality and high gamma‐aminobutyric acid (GABA) content. The initial pH value of rice slurry was adjusted to 4.5 and enriched with 2% of monosodium glutamate (MSG) before fermentation. LP was able to produce lactic acid and reduced pH better than LB but produced GABA in less content. Expanding fermentation time induced decreasing in viscosity and whiteness of flour. Fermented rice noodles provided better tensile strength and elasticity. In conclusion, LB could produce GABA in the amount of 21.80 mg/100 g dry basis in 24 h with good quality.

Improving the texture and color of <i>khanomjeen</i>, a Thai fermented rice noodle, using a modified rice fermentation method

Improving the texture and color of <i>khanomjeen</i>, a Thai fermented rice noodle, using a modified rice fermentation method

Volatile compounds, bacteria compositions and physicochemical properties of 10 fresh fermented rice noodles from southern China

To clarify the discrepancy in characteristic flavor and bacteria composition of 10 fresh fermented rice noodles from southern China, the volatile and bacteria composition were determined by headspace-gas chromatography ion mobility spectrometry and 16SrRNA sequencing methods. The potential relationship between volatile compounds and bacterial composition has also been further revealed using spearman’s correlation analysis. The contents of proximate composition, cooking properties and texture properties of 10 fresh fermented rice noodles exhibited significant different among them (p ＜ 0.05). The flavor analysis showed that a total of 54 compounds were detected. 1-Octen-one, ethyl 3-methylbutanoate, 3-methylbutanal, n-nonanal, hexanal, amyl acetate, ethanol and 2-pentyl furan were the key volatiles among them. The bacterial analysis showed that Leuconostoc and Lactococcus were the core bacteria at the genu level of all samples. Amyl acetate, 2-butanone and methyl-2-methylpropanoate were positively related to Lactococcus while ethanol was negatively correlated with Lactococcus. And Leuconostoc was positively related to 3-methylbutanal and acetone, while was negatively correlated with hexanal. Results indicated that key volatiles and textural properties of different fresh fermented rice noodle samples were associated with bacterial composition.

Basic Quality Management for Improving the Business Stability of Small Food Enterprises in Southeast Asia: The Case of a Fermented Rice Noodle Company in Thailand Preventing Noodle Liquefaction

Basic Quality Management for Improving the Business Stability of Small Food Enterprises in Southeast Asia: The Case of a Fermented Rice Noodle Company in Thailand Preventing Noodle Liquefaction

Efficient Secretion and Recombinant Production of a Lactobacillal α-amylase in Lactiplantibacillus plantarum WCFS1: Analysis and Comparison of the Secretion Using Different Signal Peptides.

Lactic acid bacteria (LAB) have been used as starter cultures and producers of enzymes, antimicrobial peptides or metabolites that contribute to the flavor, texture and safety of food products. Lactiplantibacillus plantarum, one of the best-studied LAB, is considered as safe and effective cell factory for food applications. In this study, our aim was to use L. plantarum as the producer for high levels of a food-grade lactobacillal α-amylase, which has potential applications in food, fermentation and feed industries. The native form of an α-amylase (AmyL) from L. plantarum S21, an amylolytic LAB isolated from Thai fermented rice noodles, was expressed in L. plantarum WCFS1 using the pSIP expression system. The secretion of the α-amylase was driven by the native signal peptides of the α-amylases from L. plantarum S21 (SP_AmyL) and Lactobacillus amylovorus NRRL B-4549 (SP_AmyA), as well as by three Sec-type signal peptides derived from L. plantarum WCFS1; Lp_2145, Lp_3050, and Lp_0373. Among the tested signal peptides, Lp_2145 appears to be the best signal peptide giving the highest total and extracellular enzymatic activities of α-amylase AmyL from L. plantarum S21, which were 13.1 and 8.1 kU/L of fermentation, respectively. These yields were significantly higher than the expression and secretion in L. plantarum WCFS1 using the native signal peptide SP_AmyL, resulting in 6.2- and 5.4-fold increase in total and extracellular activities of AmyL, respectively. In terms of secretion efficiency, Lp_0373 was observed as the most efficient signal peptide among non-cognate signal peptides for the secretion of AmyL. Real-time reverse-transcriptase quantitative PCR (RT-qPCR) was used to estimate the mRNA levels of α-amylase transcript in each recombinant strain. Relative quantification by RT-qPCR indicated that the strain with the Lp_2145 signal peptide-containing construct had the highest mRNA levels and that the exchange of the signal peptide led to a change in the transcript level of the target gene.

Optimization of Bacterial Cellulose Production from Wastewater of Noodle Processing by Komagataeibacter sp. PAP1 and Bio-Cellulose Paper Production

Bacterial Cellulose (BC) production from Fermented Rice Noodle Wastewater (FRNW) was fermented by Komagataeibacter sp. PAP1. In order to increase the production of BC, the FRNW-based medium was prepared and optimized for the cultivation of this bacterium. The optimized FRNW-based medium was composed of 5 % (w/v) mannitol, 0.1 % (w/v) beef extract, 0.5 % (v/v) ethanol, 1 % (v/v) acetic acid, pH 7.0 which were incubated at 30 °C for 10 days. Under these conditions, BC yielded 11.76 ± 0.34 g/L higher (4.40 fold) than the standard Hestrin-Schramm (HS) medium. The study on growth and BC production by Komagataeibacter sp. PAP1 in optimized culture condition showed that BC production by Komagataeibacter sp. PAP1 was growth-associated. The bacterial cell of Komagataeibacter sp. PAP1 increased exponentially from the 3rd to 5th day. The BC paper sheets produced using the obtained BC pellicle from an optimized FRNW-based medium gave higher mechanical strength than those from standard HS medium. This study reveals the use of FRNW as a substrate for BC production. The results indicated that FRNW, which is more environmentally friendly, can be used as an alternative low-cost substrate for BC production.

Flavor Analysis and Strain Exploitation of Fermented Rice Noodles

<p align="justify">Fermented rice noodles is popular for its unique flavor, but the study on flavor is lacking, especially the screening of corresponding strains. For the first time, the relationship of microorganism and flavor was unveiled, based on the research of a typical fermented rice noodles from Guilin in China. Flavors were dissected by HPLC-MS, GC-MS, GC-MS-O (Gas chromatography-mass and spectrometry-olfactometry) analyses, while microbial community was investigated by amplicon sequencing and metagenomics, afterwards microorganisms and flavors were connected via correlation analysis and function annotation, hen strains could be explored based on the analyses. Ethanol, 1-butanol,3-methyl-, 2-butanone, 3-hydroxy-, acetic acid and phenylethanol were discovered to be key flavors, biogenic amines were not abundant enough to have bad effect on flavor, but putrescine, tyramine and histamine produced in fermentation needed supervision for safety. Analysis indicated that fermentation was dominated by lactic acid bacteria. Further analysis revealed that Lactobacillus, Acetobacter and Lactococcus were primary creators for these key flavors. In particular, Lactobacillus showed great potential in flavor forming. Additionally, later experiment suggested that samples fermented by L. fermentum and L. plantarum (both belong to Lactobacillus) possessed great flavors, when L. fermentum also showed the ability to inhibit mold and reduce biogenic amine content.</p>

The utilization of wastewater of Thai fermented rice noodle (Kanom-jeen) manufacturing process for the production of bacterial cellulose by Acetobacter xylinim TISTR 975

Bacterial cellulose (BC) is a naturally produced as an exopolysaccharide from some bacteria. It has excellent properties over the plant cellulose and has numerous applications in many fields including food, pharmaceutical, textile, paper manufacturing and other industries. However, a major limitation of bacterial cellulose production is the high cost of carbon substrate. The study aims to reduce the cost of bacterial cellulose using a cheap carbon source. This study presents feasibility in the production of bacterial cellulose using the starchy effluent waste from the Thai fermented rice noodle manufacturing process as a low-cost substrate by Acetobacter xylinum TISTR 975. The optimizations of culture conditions for bacterial cellulose production were also investigated under static culture. The results indicated that starchy effluent waste from the Thai fermented rice noodle manufacturing process performs well for the production of bacterial cellulose by supplementing with 50 g/L sucrose and 2% olive oil under the static condition. The structure and physical properties of bacterial cellulose were characterized using SEM, FTIR and XRD. In summary, the starchy effluent waste from the Thai fermented rice noodle manufacturing process can be used to produce bacterial cellulose which is a high value-added, sustainable and green product.

Effects of Lactobacillus plantarum Inoculum on the Fermentation Rate and Rice Noodle Quality.

To accelerate the fermentation rate and reduce the adverse effects of undesirable microorganism contamination on rice noodle quality, the pure inoculum fermentation method was used to produce fermented rice noodles. The results indicated that the pure inoculum fermented rice slurry required 10 h to reach a stable pH value. While, the pH value of the natural, pure and natural inoculum fermented rice slurries required 54, 18 and 20 h to stabilize, respectively. Free amino acids and lactic acid concentrations of the pure inoculum fermented rice slurry were higher than those of the natural and natural inoculum fermented rice slurries. The pure inoculum fermentation modified the proximate composition and lowered the pasting viscosities of the rice flour. The texture, cooking and eating qualities of the pure inoculum fermented rice noodles were similar to those of the natural fermented ones. In addition, the pure inoculum fermented rice noodles had higher relative contents of aldehydes than other fermented rice noodles and thus had a better flavor. Therefore, pure inoculum fermentation accelerated the fermentation rate and improved the rice noodle flavor while maintaining the texture, cooking and eating qualities of the rice noodles.

Effect of proteolytic bacteria on texture and colour quality of khanom-jeen, traditional Thai fermented rice noodles.

Khanom-jeen are traditional Thai fermented rice noodles with a characteristic flavour and texture. Based on their ability to hydrolyse rice proteins, five strains of proteolytic bacteria were isolated from fermented rice flour used to produce noodles in Thailand. Enterobacter ludwigii strain SK01 showed the highest degree of rice protein hydrolysis among the five strains and was selected as a starter culture for khanom-jeen production. The viable count of micro-organisms, acidity, pH, and protein and starch contents were compared throughout the fermented rice production with and without the SK01 strain. The pH of fermented rice increased on the first day of solid-state fermentation and subsequently decreased to 3·7-3·8 under both conditions. The protein content of rice significantly decreased from 80 to 18·2±0·5mgg-1 and 26±0·6mgg-1 during fermentation with and without the SK01 strain, respectively. The tensile strength, breaking length, brightness, and whiteness, which are important factors for the texture and appearance of khanom-jeen, were improved using the SK01 strain to ferment rice. The results of this laboratory-scale study indicated that the use of the proteolytic SK01 strain in fermented rice production can improve the quality of khanom-jeen noodles. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of Enterobacter ludwigii strain SK01 as a proteolytic bacterial starter culture improved the quality of khanom-jeen noodles. Compared with khanom-jeen noodles produced without E. ludwigii strain SK01, those produced using this strain showed increased tensile strength, breaking length, brightness and whiteness. These findings will be useful for the development of specific and controllable methods for producing khanom-jeen noodles with desirable texture and colour.

Assessment of microbiological quality and safety of fermented and non-fermented Khmer Rice Noodles in Cambodia

Fermented and non-fermented Khmer rice noodles is produced basically from indica rice, a popular food item and most important nutrition sources along with an integral part of rural household’s food security of Cambodian population. This study was done to evaluate the microbiological quality of fermented and non-fermented Khmer rice noodle samples sold throughout the country. In total, 75 Khmer rice noodle samples, (23 fermented and 52 nonfermented) were collected from five local varieties (Nom-Banhchok, Nom-Banhhoy, Koyteavkat, Lotchhar and Koyteav) and three locations (Kandal province, Siem Reap province and Phnom Penh city) of Cambodia. The study results showed that irrespective of sample location, all the fermented and non-fermented rice noodle samples analyzed were either contaminated with faecal origin bacteria (Enterococcus spp., and coliform), or faecal indicator bacteria including Escherichia coli and pathogenic bacteria including, Staphylococcus spp., and Bacillus spp. Of the fermented rice noodles about 74% and 98% of non-fermented rice noodles was found contaminated with all the above mentioned bacteria. In addition, 30% samples were found contaminated with Klebsiella pneumonia spp. Furthermore, among the Staphylococcus aureus isolates, three isolates TM-K5-3, OM-L4 and DM-KK3-2 was seen producing protein A (aggregated polysaccharide specific immune latex strongly), positive clumping factor production and harbored type six coagulase gene and among the B. cereus strains, 12 B. cereus, isolates was seen produced enterotoxin, which may cause severe diarrhea and one B. cereus (DM-NB1) isolate was found harbored CRS gene, which may produce emetic toxin, unsafe for human consumption. Therefore, strong regulatory monitoring should be established in order to improve the quality of food to ensure public health.
 Bangladesh J Microbiol, Volume 35 Number 2 December 2018, pp 82-88

Effects of Lactobacillus combined with semidry flour milling on the quality and flavor of fermented rice noodles

To shorten the fermentation time and reduce the contamination with heterozygous bacteria during the process of fermenting rice noodles, pure bacterial fermentation combined with semidry flour milling was used to produce fermented rice noodles. The changes in the pH value and microbial community diversity of the rice slurries, the physicochemical properties of the rice flours, and the texture, cooking qualities, sensory qualities and volatile components of the rice noodles prepared with different fermentative methods were investigated. The results showed that the pure bacterial fermentation required 18 h to reach a stable pH value, while the natural fermentation required 54 h. In addition, compared with naturally fermented rice slurry, the bacterial community diversity of the pure bacterial fermented rice slurry was significantly lower, while the fungal community diversity did not differ significantly. Significant differences were observed in the content of the damaged starch, amylose and protein between semidry milled pure bacterial fermented (SP) and wet milled naturally fermented (WN) rice flours (P < .05), while these differences had no significant effect on the texture and cooking qualities of the SP and WN rice noodles (P > .05). In addition, the types of volatile components of the SP noodles were significantly lower than those of other noodles, while the primary volatile component categories of the SP noodles were consistent with that of the WN noodles, and they had a similar flavoring substance.

Study on optimization of removing cadmium by lactobacillus fermentation and its effect on physicochemical and quality properties of rice noodles

In recent years, cadmium (Cd) contaminated rice has aroused widespread concerns about the safety of rice or its products, and microbial fermentation has been proved to be a promising method for reducing Cd. The fermented rice flour can be applied as the main ingredient of rice noodles, a traditional breakfast staple in southern China. This study is aimed to screen out the optimum conditions for reducing Cd in rice noodles by mixed-Lactobacillus (LAB) fermentation, and to study its effect on the physicochemical and quality properties of rice noodles. The results revealed that the best condition of wet digestion for Cd detection in 0.5 g fermented rice noodles was following: digestive agent of 7 ml nitric acid (GR) + 3 ml perchloric acid (GR) +1 ml hydrogen peroxide (30% GR), digestion at 90 °C, 150 °C and 250 °C for 30 min, 60 min and 120 min, respectively. The optimized fermentation condition for decreasing the Cd concentration in rice flour was fermented by 8% (v/v) of mixed-LAB at 35 °C for 28 h, with the reduction of 87.6%. The mixed-LAB fermentation in rice flour was found to increase the concentrations of amylose and reducing sugar, improve its swelling power and gel properties, and produce lactic acid with the maximum amount of 612.1386 mg/L; while its rheological characteristics were significantly affected. Moreover, the quality properties of rice noodles made by the above fermented rice flour had also been improved, with higher hardness and chewiness, shorter rehydration duration, higher rehydration rate, less cooking loss and broken rate. These results showed that the fermentation by mixed-LAB can efficiently reduce excess concentration of Cd in rice flour, improve its physicochemical properties, and promote the quality property improvement of rice noodles made by it.

Characterization and Antibacterial Activity Against Helicobacter pylori of Lactic Acid Bacteria Isolated from Thai Fermented Rice Noodle.

A total of 32 lactic acid bacteria (LAB) were isolated from Khanom-jeen, a Thai traditional fermented rice noodle. They belonged to the genus Leuconostoc (Ln), Lactobacillus (Lb), Enterococcus (E), Lactococcus (Lc), and Weissella (W), based on their phenotypic characteristics and 16S rRNA gene sequence analyses. The strains were identified as Ln. pseudomesenteroides (group 1, two strains), Ln. citreum (group 2, three strains), Ln. lactis (group 3, three strains), Lb. paracasei subsp. tolerans (group 4, two strains), E. faecium (group 5, three strains), Lc. lactis subsp. lactis (group 6, one strain), W. confusa (group 7, six strains), Lb. fermentum (group 8, seven strains), and Lb. plantarum subsp. plantarum and Lb. pentosus (group 9, five strains). Fifteen strains exhibited the inhibitory activity against Helicobacter pylori clinical isolates by spot-on-lawn method. Lb. fermentum P43-01 resisted to bile acids showed the broad spectrum of antimicrobial activity against H. pylori strains MS83 and BK364. These antagonistic effects were associated with proteinaceous compounds which are sensitive to α-chymotrypsin and pepsin. Results indicated that production of bacteriocin-like substances of selected strain might be the significant mechanism that exerted the inhibition on H. pylori. A potential strain could be used as probiotics in alternative or adjunctive therapy for a patient suffering from H. pylori infection.

Effects of gums on physical properties, microstructure and starch digestibility of dried-natural fermented rice noodles

The effects of gums including carboxymethyl cellulose (CMC), xanthan gum (XG) and guar gum (GG) on physical properties, microstructure and starch digestibility of dried-natural fermented rice noodles were investigated. The gums, each at 0.05 and 0.10 g/100 g wet basis, were added to the flour during rice noodle production. Control was the sample without the addition of gums. Physical properties (color, water absorption, cooking loss and firmness), microstructure, starch composition and in vitro starch digestibility were determined. Generally, the addition of gums improved the physical qualities of rehydrated fermented rice noodles as evidenced by high water absorption and low cooking loss. CMC provided the best result for improvement of the physical properties of rice noodles. The addition of gums promoted the porous microstructure in rice noodles. In terms of starch digestibility, the addition of gums increased the rate of starch digestion and consequently provided high estimated glycemic index (GI). Samples with XG showed the highest starch digestion rate and estimated GI values when compared with CMC and GG. It is concluded that CMC, XG and GG improved the texture and cooking quality of dried-natural fermented rice noodles but they had negative effects on starch digestion rate and estimated GI.