Tofu Samples Research Articles

Microbiological quality of vegan alternatives to dairy and meat products in England during 2022-3.

Plant-based alternatives to meat and dairy products have become increasingly popular in the UK. Despite a public perception that they have a relatively low microbiological risk, outbreaks of illness have been linked with these foods. This study aimed to assess the microbiological safety and quality of vegan alternatives to dairy and meat products available in England. Samples were collected between September 2022 and March 2023 from retail, production, and catering premises, and tested for a range of bacterial pathogens and hygiene indicators using standard procedures. A total of 937 samples were tested, of which 92% were of a satisfactory microbiological quality, 3% were borderline, and 5% were unsatisfactory. Those interpreted as unsatisfactory were due to elevated counts of Enterobacteriaceae and Escherichia coli (indicators of poor hygiene) rather than pathogenic microorganisms. Listeria monocytogenes was present in five samples of tofu, all from the same producer (all at counts of<100 CFU g-1), while other Listeria species were detected at counts of<20 CFU g-1 in two burgers and two 'vegan chicken' products. The majority of samples did not have pH and water activity values that would significantly contribute to preventing microbial growth: 62.4% had pH>5.0 and 82.4% had Aw>0.94. The majority of vegan products examined were of a satisfactory quality, but results demonstrate that microbiological control must be maintained using appropriate processing and storage temperatures, and application of a safe length of shelf life.

Gelling properties of acid-induced tofu (soybean curd): Effects of acid type and nano-fish bone.

The effects of different types of acid coagulants and nano fish bone (NFB) additives on the characteristics of tofu were investigated using texture analyzers, SEM, FT-IR, and other techniques. The breaking force and penetration distance, in descending order, were found in the tofu induced by glucono-d-lactone (GDL) (180.27g and 0.75cm), citric acid (152.90g and 0.74cm), lactic acid (123.33g and 0.73cm), and acetic acid (69.84g and 0.58cm), respectively. The syneresis of these tofu samples was in the reverse order (35.00, 35.66, 39.66, and 44.50%). Lightness and whiteness were not significantly different among the different samples. Regardless of the acid type, the soluble calcium content in the soybean milk was significantly increased after adding NFB. As a result, the breaking force and penetration distance of all tofu samples increased significantly, but the syneresis decreased. Compared with tofu coagulated by other acids, GDL tofu formed a more uniform and dense gel network maintained by the highest intermolecular forces (especially hydrophobic interactions). Regarding the secondary structure, the lowest percentage of α-helix (22.72%) and, correspondingly, the highest β-sheet (48.32%) and random coil (18.81%) were noticed in the GDL tofu. The effects of NFB on the tofu characteristics can be explained by the changes in the gel network, intermolecular forces, and secondary structure, which were in line with the acid type. The characteristics of acid-induced tofu can be most synergistically improved by coagulation with GDL and NFB.

Identification of Formalin in Raw Tofu from Sidenreng Rappang District Traditional Markets

Formalin (Formaldehyde) is a chemical compound whose use is prohibited as a preservative in food additives. This study aims to analyze the content of formalin (Formaldehyde) in raw tofu circulating in Sidenreng Rappang district. The test method used was by qualitative analysis using Schiff reagent and KMnO4. The quantitative analysis using the UV-Vis spectrophotometry method. The test results used Schiff reagent and KMnO4, the four tofu samples contained formalin. Test results on the UV-Vis Spectrophotometry method at a wavelength of 555 nm, obtained formalin levels in sample with sample code A = 1.130%, sample code B = 1.826%, sample code C = 1.84%. It can be concluded that in the formaldehyde qualitative analysis test on raw tofu, the three samples positively contained formaldehyde. As well as the results of the measurement of the three positive samples containing formaldehyde using a UV-Vis spectrophotometer.

Effects of Sodium Alginate on the Physical Properties and Storage Stability of Freeze-Dried Tofu Coagulated with Crab Shell Extract.

The amount of processed by-products such as crab shells is increasing, but industrial utilization is insufficient. In our previous study, crab shell extract (CSE) acted as a coagulant for tofu manufacturing. This study aimed to reduce freeze-dried (FD) tofu breakdown by improving its physical properties through adding sodium alginate (SA). FD state in tofu helps increase storage and availability, but FD tofu frequently fractures during processing, which is a concern for manufacturers. Tofu samples were prepared with either crab shell extract (CSE) or MgCl2, and SA, and freeze-dried. In the yields of FD tofu samples, there were no significant differences (p < 0.05). The brokenness of FD tofu samples was lower in CSE than in MgCl2 and was significantly reduced by SA in both tofu samples, which was affected by hardness. The water-holding capacity decreased after freeze-drying, and CSE reduced this decrease, regardless of SA addition. The microstructures differed depending on the coagulant and were dense upon SA addition. The FD tofu was packed into a multilayer film and stored at 25 °C or 45 °C for 6 months to investigate storage stability. During the storage, brokenness was unchanged in all tofu samples, indicating that they maintained their original structure. There were no significant differences in the volatile base nitrogen and thiobarbituric acid values according to the coagulant type and SA addition (p < 0.05). In conclusion, SA reduced FD tofu breakdown by improving the network structure, which may help increase FD tofu quality and decrease economic loss.

Analysis of genetically modified soya and soya products using a fluorescence probe based on PCR-initiated isothermal amplification of G-quadruplex DNA

We proposed a novel strategy for the analysis of genetically modified (GM) soya samples by combining PCR-initiated generation and isothermal amplification of G-quadruplex DNA. PCR primers were designed to consist of a target-specific sequence, a G-quadruplex complement sequence, and a nicking endonuclease recognition site. After the PCR step, the nicking enzyme cut the recognition site, and single stranded G-quadruplex sequences were displaced and further amplified by polymerase during the isothermal amplification reaction. Then, the G-quadruplex sequences combined with N-methyl mesoporphyrin IX to generate strong fluorescence. This method has a detection limit of 0.2% and a linear range from 50% to 0.5% GM content. When exponential isothermal amplification was coupled to the preceding amplification step, the detection limit was further improved to 0.02% GM soya. GM contents were successfully detected at 0.1% GM percentage in soy milk and 0.9% GM percentage in tofu and dried tofu samples. The method may be applied to the analysis of various GM species simply by changing the target sequence in the primers.

Influence of mealworms (Tenebrio molitor larvae) and their protein derivatives on the structural and rheological properties of tofu

This study investigates the effects of incorporating mealworms into tofu, regarding its structural and rheological properties. Tofu samples were prepared using only soybean flour (S), or by replacing soybean flour with mealworms (M), mealworm protein isolate (MPI), or mealworm protein hydrolysate (MPH) at a 1:1 ratio (SM, SMPI, and SMPH, respectively). Results revealed that S partial substitution with M, MPI, and MPH affected the particle size, polydispersity index, and zeta potential of soymilk. Intrinsic fluorescence and surface hydrophobicity showed the early formation of large aggregates in SMPI. As for tofu, gelation of SM mainly occurred due to soybean protein-protein interactions, suggesting that M can prevent gelation, as evidenced by the SDS-PAGE and ATR-FTIR patterns. SMPI had the highest ionic bonds, hydrogen bonds, and hydrophobic interaction content, whereas S had the highest SS bond content. Furthermore, SMPH, enriched with small molecules, exhibited the highest proportion of random coil and disrupted amide bands, leading to limited protein-protein interactions. Finally, apparent viscosity of soymilk, temperature sweep during tofu preparation, frequency sweep, and microstructure analyses of tofu indicated that MPI contributed to hardness (927.9 g/cm2) and gel-like properties, while M and MPH led to softer (135.0 g/cm2 and 32.0 g/cm2, respectively) and more liquid-like tofu compared to S (504.3 g/cm2). In conclusion, this study provides insights into selecting mealworm derivatives with varying structural and rheological properties, enhancing their applicability in gel-type food systems.

Effects of Starch Addition on KGM Sol's Pasting, Rheological Properties, and Gel Texture.

Konjac tofu is an irreversible gel formed by removing the acetyl group from konjac glucomannan (KGM) through alkaline heating. This type of food is low in calories, filling, and healthy, making it popular in the market. However, pure konjac tofu has a hard texture and lacks flavor when heated. To improve its taste and appearance, the effects of three varieties of native starch, including corn starch (CS), Canna edulis Ker starch (CKS), and potato starch (PS), on the formation of pasting and rheological properties of the KGM sol were investigated. Konjac tofu samples that incorporated different types and quantities of starch were prepared and analyzed in terms of structure, texture, dehydration, and flavor, with pure konjac tofu serving as a reference. The findings revealed that KGM mixed with a concentration of 4.2% CS, or 0.85% CKS, or 0.85% PS of the total mass produced a gel with the highest viscosity and a steady structure. Texture profile analysis indexes of these combinations were superior to pure KGM, and the konjac-starch tofu had a lamellar network structure. Thus, konjac tofu with the addition of starch has a higher quality texture, lower dehydration, and improved flavor compared to pure KGM gel.

Analisis Kandungan Formalin dan Boraks Pada Bakso dan Tahu di Wilayah Kota Malang

The main danger posed by formalin and boric acid or often called borcas if exposed continuously is that it can irritate the respiratory tract if inhaled, cause skin blisters if in contact with skin, nausea, vomiting, diarrhea, possible bleeding, abdominal pain, headache, hypotension, fainting. to coma. In addition, formalin can cause degenerative changes in the liver, heart, brain, other organs and can trigger genetic mutations resulting in cell damage or cell death which can result in the growth of cancer cells. This study aims to identify the content of formalin and boric acid or borkas in food samples of meatballs and tofu. The method used in this research is to test for boric acid or borcass by using AgNO3 and Paper Test Kit and for testing Formalin using KMnO4 and Reagent Test Kit. This method is used as a qualitative test for the presence of formalin and borax or boric acid in the sample. A positive result for the presence of borax or boric acid with AgNO3 with the occurrence of a white precipitate and using a paper test kit will turn brown. To identify formalin, a positive result with KMnO4 is indicated by a change in color to brown and using a test kit reagent is indicated by a change in the color of the positive sample to purple. The samples tested were 3 meatball samples and 3 tofu samples. The results of the identification of formalin and borax or boric acid in all meatball and tofu samples were obtained using qualitative tests, no meatball and tofu samples containing formalin and borax or boric acid were found.

A comparative study on the physicochemical characteristics and protein digestibility of tofu induced by magnesium chloride or combined with transglutaminase

SummaryIn this study, tofu was prepared through the addition of transglutaminase (TGase) for pre‐crosslinking at varying durations (1, 2 and 3 h), followed by the addition of magnesium chloride (MgCl2) to soymilk. The physicochemical properties and protein digestibility were analysed. Results indicated that, with the prolongation of TGase pre‐crosslinking time, the zeta‐potential absolute value and the average particle size of soymilk increased gradually. In contrast, the pH value remained unchanged (P &gt; 0.05), suggesting that the colloidal stability of soymilk improved with TGase treatment. Both the water‐holding capacity (WHC) and gel strength of tofu gels exhibited a first increasing and then decreasing trend with prolonged pre‐crosslinking time. Notably, the highest WHC and hardness values of tofu gels prepared by adding MgCl2 after pre‐crosslinking with TGase for 1 h were 96.5 ± 0.5% and 363.9 ± 28.3 g, respectively. Subsequently, in vitro simulated gastrointestinal digestion of tofu samples prepared under this condition was conducted to determine changes in soluble protein content, small peptide content and protein hydrolysis spectrum. Gastric and intestinal digestion phases were the primary stages of protein hydrolysis, and the bioavailability of proteins in TGase+MgCl2‐induced tofu was higher than in MgCl2‐coagulated tofu. Therefore, tofu prepared through TGase pre‐treatment was more conducive to soybean protein digestion and absorption.

Identification Test Of Borax And Formaline Content In Food Sold At Laguboti Market

Food is one of the human needs in everyday life. As a basic need, these foods must contain nutrients to be able to fulfill this function and be safe. Preservatives and dyes seem to be inseparable from various types of processed food and beverages. The purpose of this study was to determine the presence or absence of borax and formalin in food sold at the Laguboti Market. Based on Permenkes Number 033 of 2012 concerning food additives, borax is not allowed in food. If borax and formalin are consumed by humans, it will have a negative impact on the body. This study used a descriptive method, namely the scientific method and the simple method and was carried out in July at the Chemistry Laboratory of STIKes Arjuna Laguboti with a total sample of 14 food samples purchased from different food vendors at the Laguboti Market. Based on the results of a qualitative analysis on borax using the scientific method and the simple method obtained from 3 meatball samples and 3 rice cake samples, none of the meatballs contained borax. In formalin Using the scientific method and simple methods obtained from 5 samples of tofu and 3 samples of wet noodles containing formalin.

PERBEDAAN HASIL KADAR FORMALIN PADA SAMPEL TAHU YANG DIRENDAM AIR HANGAT DAN AIR GARAM MENGGUNAKAN METODE SPEKTROFOTOMETRI UV-VIS

Problems: Formalin Examination is use to determine of presence or absence of harmful substances or preservatives in samples tested or examined on food, especially tofu. The Aim Of The Research: To determine the difference in the results of formaldehyde levels in tofu samples soaked in warm water and salt water using UV-Vis Spectrophotometry method. Research Method: The type of research used was a pure experiment, which was conducted at the Laboratory of Chemistry and Microbiology of Agricultural Products, Department of Agricultural Technology, Faculty of Agriculture, Unsri Palembang. The sample used was tofu and the number of careful samples was 18 tofu samples using the total sampling technique. The Result: Based on the results of examining the formalin content in tofu samples soaked in warm water for 15 minutes using the UV-Vis Spectrophotometry method with the A &amp; E Visible Spectrophotometer yielded an average of 0.56 mg/L while the results of examining formalin levels in tofu samples soaked in salt water produces an average of 0.74 mg/L. Data analysis using the Independent Sample T-Test test obtained a significant value for the warm water treatment p = 0.395 and a significant value for the salt water treatment p = 0.397. Conclutions: There are differences in the results of formalin levels in tofu samples soaked in warm water and salt water using UV-Vis Spectrophotometry method.

INFLUENCE OF CHICKEN EGGSHELL POWDER AS AN ALTERNATIVE COAGULANT ON THE YIELD AND TEXTURAL CHARACTERISTICS OF TOFU

Daily consumption of chicken eggs produces a vast number of eggshells byproducts which are a rich source of calcium salt. This paper investigated the potential of eggshell powder from eggshell byproducts as an alternative coagulant in the tofu preparation process. The eggshell powder was successfully obtained and analyzed with calcium salt (CaCO3) of 74.7% followed by calcium of 17.48%. Liquid nigari as a coagulant was evaluated and showed better tofu yield (143.24 ± 1.68 g/ 100 g) at 2% of addition to the soybean milk. The tofu prepared with 2% liquid nigari and 0.25% eggshell powder showed a higher yield (154.79 ± 3.56 g/100 g) as well as the improvement of texture profile of resulting tofu with hardness of 19.1 ± 2.02 N, cohesiveness of 0.26, and springiness of 13.5 ± 0.06 mm. The studied tofu was obviously observed to have better textural characteristics than two samples of tofu prepared by traditional methods. The result suggested that eggshell powder could be a promising alternative coagulant for tofu preparation.

A ANALISIS KUALITATIF FORMALIN PADA TAHU YANG BEREDAR DI PASAR DESA KUPU KOTA BREBES

Tofu has a high protein content and water content reaches 85% so that tofu does not last long. One way to prevent damage to foodstuffs is to add preservatives. Formalin is a preservative that is sometimes misused as a preservative in foodstuffs. The research that has been conducted aims to determine the presence or absence of formalin in tofu sold at the Pasar Desa Kupu. The type of research used is descriptive research. Five samples of tofu obtained from traders at Pasar Desa Kupu were then analyzed using a qualitative method using a color reaction. All samples showed positive results with the loss of KMnO4 color and became clear. The same results were shown by the dragon fruit peel kit method.

Effects of sprouting of soybean on the anti-nutritional, nutritional, textural and sensory quality of tofu

Soybean (Glycine max) is a superior plant food known as the miracle golden bean due to its treasure trove of inexpensive and superior protein to high-priced meat protein. Tofu is typically thought of as a salt or acid-coagulated water-based gel containing soy lipids and proteins trapped within its gel networks. Sprouted tofu is easier to digest and contains more nutrients than regular tofu. The purpose of this study was to evaluate the nutritional and sensory quality of tofu. The study was concerned with the preparation of tofu from non-germinated and germinated soybeans of 0 (T0), 2 (T1), 4 (T2) and 6 (T3) days. The length of the radicle was 0.8, 1.5, and 2 inches for T1, T2, and T3, respectively. Lipoxygenase activity, phytate inhibitory activity, urease activity, trypsin inhibitory activity, protein solubility, nutritional, and sensory quality of prepared tofu were all assessed. Longer sprouting times reduced phytate, urease, trypsin, and lipoxygenase activity while increasing protein solubility. Tofu prepared from T3 showed significantly better physicochemical properties than others. Protein, ash, and fat contents were significantly higher in T3. The level of nutrient content for tofu samples was in the rank of T3>T2>T1>T0. The L∗, a∗ and b∗ values were followed the same ranked as nutrient content (T3>T2>T1>T0). Sensory characteristics indicated that T3 was significantly more acceptable to the panelist. This study concludes that tofu made from 6 day sprouted soybeans with a height of 2 inches can be a good source of nutrition for consumers.

Antioxidant edible double-layered film based on waste from soybean production as a vegan active packaging for perishable food products

Edible vegan films were obtained on the basis of furcellaran and protein hydrolysates from soybean bran. The aim of the study was to investigate the possibility of using innovative single- and double-layer films with antioxidant properties as packaging materials for vegetarian products. A further objective of the study was to evaluate the degree of biodegradation and potential toxicity with regard to the developed films. The tofu was analysed for changes in physicochemical parameters (weight loss, dry weight texture and colour), microbiological quality (total microbial count, yeast and moulds, psychotropic bacteria), and lipid oxidation (peroxidase and acid values, TBARS, fatty acid profile). It was found that films undergo almost complete biodegradation within 10 days and do not demonstrate any toxicity for cress seeds during their growth. Films are not effective in inhibiting the growth of microorganisms in tofu samples. Furthermore, they are not efficient in inhibiting the oxidation of tofu lipids. Compared to the control, the tofu samples covered with the innovative biopolymer films showed significantly lower moisture content and higher weight loss as well as hardness during the whole storage period.

The Comprehensive Utilization of Bean Dregs in High-Fiber Tofu.

A large quantity of bean dregs is produced by the production of tofu and treated as animal feed or plant fertilizer, which could cause environmental pollution. The purpose of this study was to use commercially available lactone tofu to compare the effects of innovative preparation methods of high-fiber tofu, where the innovative methods used partial de-slagging followed by the addition of soybean residue cellulose to prepare high-fiber tofu. The results showed that there were no significant differences among lactone tofu samples made with 5% cellulose, 10% cellulose, or 15% cellulose and the commercially available lactone tofu during the water-holding capacity and chroma analysis. Texture indices showed that lactone tofu with 10% cellulose was similar to the commercially available lactone tofu in chewiness and hardness, and lactone tofu with 15% cellulose was similar to the commercially available lactone tofu in adhesiveness and chewiness. Magnetic resonance imaging displayed that lactone tofu with 10% cellulose had better water retention and higher moisture content. Gel electron microscopy showed that lactone tofu with 10% cellulose achieved a better gel network, and the bean dreg cellulose had less influence to a certain extent. Volatile organic compound testing by GC-IMS method indicated that the lactone tofu with 10% cellulose had more volatile organic compound content. In conclusion, these results demonstrated that lactone tofu with 10% cellulose had the best market competitiveness in ensuring the quality of high-fiber tofu.

The Role of Anthocyanin Substances from Dragon Fruit Skin Extract in Formalin Content Testing in White Tofu

One of the high-quality processed vegetable food ingredients is tofu. Tofu is made from processed soy milk with a thick texture and molded according to the right nutritional amount. White tofu is the most popular of the various forms of tofu available. Today, tofu producers have taken manipulative actions to anticipate production losses by including preservatives in the mix of ingredients used to make tofu. Most of the tofu production centers provide additional ingredients in the form of preservatives such as formalin to reduce losses from damage to the tofu they produce. The presence or absence of formalin in food can be detected using a unique component found in dragon fruit peel called anthocyanins. The methodology applied in this research is a simple and direct one, with primary data collected in the form of testing samples of white tofu collected from numerous traditional markets in the Banten area (up to ten samples). The aim of the research is to identify formalin in white tofu discovered in numerous traditional markets in Banten using natural component extracts, including dragon fruit peel extract. The results stated that there were two positive samples containing formalin and eight negative samples; the presence of formalin in tofu was indicated by a red color on the tissue. Sellers or customers can detect formalin simply by utilizing dragon fruit, allowing them to avoid formin which is harmful to health, with a simple and low-cost method.

ANALISA KANDUNGAN FORMALIN PADA PRODUK TAHU PUTIH DI KECAMATAN WONGSOREJO

Tofu is one source of protein from white soybeans by finely milling, boiling, and printing. The shelf life of tofu is very limited, under normal conditions (room temperature) the shelf life is on average 1-2 days, if more than this limit the taste of tofu will turn sour and give rise to a rotten aroma so it is not suitable for consumption. This makes foods such as tofu often added with chemicals or natural ingredients to make them last longer. One of the chemicals that is dangerous and often used is formalin, so there is a need for research on the content of formaldehyde in white tofu, especially in Wongsorejo District because white tofu is one of the foods that are often consumed by the community. This research was initiated by collecting tofu samples from four tofu factories in Wongsorejo District, namely Wongsorejo Village. The test was carried out qualitatively by using the Formalin Test Kit method. Based on the physical test and qualitative formalin test conducted on the four tofu samples taken from factories in the Districts of Wongsorejo, Sumberkencono, Bajulmati, and Sidodadi, it was found that all samples did not contain formalin.

Evaluation of optical properties of tofu samples produced with different coagulation temperatures and times using near-infrared transmission spectroscopy

To investigate the feasibility of using near-infrared (NIR) spectroscopy to evaluate the coagulation extent of tofu, the optical properties of tofu samples obtained with different coagulation temperatures and times were measured in the wavelength range 1300–1800 nm. The apparent absorbance was measured using the NIR transmission spectrum, and then divided into absorption and scattering components by curve fitting. The apparent absorbance increased over the entire wavelength range as the coagulation temperature increased, in which the scattering increase was dominant over that of the absorption. The viscosity was measured as an index of the physical properties of tofu, which increased with the coagulation temperature and had a high correlation (R2 = 0.803) with one of the fitting parameters of the scattering. The microstructure of the tofu became finer as the coagulation temperature increased, which suggests that the increase in scattering might be due to changes in the microstructure. Furthermore, the light scattering increased with the coagulation time as well as with the coagulation temperature. The increase in scattering with the coagulation time followed the first-order reaction kinetics. Both scattering intensity and increase speed were larger at shorter wavelengths. This can be explained by the theory of Mie scattering and multiple scattering, indicating that scattering measurements at shorter wavelengths are useful for monitoring of coagulation. Thus, light scattering measurements using NIR spectroscopy are promising for investigating the physical properties of tofu.

Establishment of an appropriate method for determining multiple heterocyclic amines in soy products processed with various methods

A method using UPLC-MS/MS and a core–shell C18 column was developed to simultaneously determine 21 heterocyclic amines (HAs) in 15 min. Appropriate QuEChERS conditions were also established to conveniently extract HAs from soy products cooked with various methods. These conditions presented good analytical performance; limit of detection, limit of quantification, recovery (%), repeatability (coefficient of variation (CV) %) and intermediate precision (CV%) were 0.008 ∼ 0.150 ng/g, 0.025 ∼ 0.500 ng/g, 62 ∼ 91%, ≤ 28% and ≤ 23% for tofu sample, and 0.003 ∼ 0.100 ng/g, 0.010 ∼ 0.350 ng/g, 64 ∼ 93%, ≤ 19% and ≤ 20% for soy milk sample, respectively. HAs contents in the samples increased with cooking temperature and time. The tofu samples cooked by frying had much higher HAs content than those cooked by boiling and roasting. Norharman and Harman mainly contributed HAs content in all samples. For the general population in Taiwan, the highest estimated level of HAs consumed from the samples is 373.67 ng/day.