Mold Counts Research Articles

Using optimization method for determining lactic acid bacteria counts in white cheese with different salt concentrations

Total lactic acid bacteria, Lactococcus spp., yeast, and mold counts in white cheese were determined during 55 days of storage in brine solutions with 4%, 6%, 8%, 10%, 12%, 14%, and 16% (w/v) salt concentrations at 4°C. In addition to salt content, dry matter, acidity, protein, fat contents, and sensory evaluations of cheese were also determined. Lactococcus spp. numbers in cheese salted with 4% and 14% brines (w/v salt concentrations) were 9.32 and 8.48 log cfu/g at the 55 days of storage, respectively. The lowest total lactic acid number was 7.24 for cheese in brine with 16% (w/v) salt concentration after 55 days of storage. Yeast numbers were 7.01 and 6.71 log cfu/g for cheese in brines with 4% and 16% (w/v) salt concentrations. Cheese samples salted in 12% and 14% (w/v) concentrations of brines have the highest sensory scores. Analysis results were interpreted mathematically by “fuzzy soft set” modeling. Novelty impact statement This research is a novel study detailing mathematical modeling related to optimizing the salt concentration to preserve the viability of lactic acid starter culture bacteria in the white cheese. Also, it covers the first optimizing method for process control in the cheese industry with the application of “fuzzy soft set theory.”

Physico-chemical and microbiological changes occurring in Kuru Kaymak (atraditional dairy product in Turkey) during storage

The aim of this study was to determine the changes in some physicochemical and microbiological properties of Kuru Kaymak (KK) (Dry Clotted Cream) during 30 days of storage at 4°C. Kuru Kaymak samples were produced in a local family business on a small scale using the traditional method. The dry matter, fat, protein, lactose and ash content, and the water activity value of KK samples on the 30th day were 97.4%, 64.2%, 23.5%, 4.40%, 1.69% and 0.59, respectively. Unlike other high-fat dairy products, Kuru Kaymak samples were found to contain a fairly high amount of protein (23.5%). The free fatty acid value showed an enormous increase of 266.7% from 0 to 30 days. Yeast and mould counts of KK samples were below the countable level (<2 log cfu/g) throughout storage. The presence of coliform bacteria in KK samples showed that there was contamination due to non-compliance with hygienic rules in production. Considering the properties examined, it was concluded that KK could be stored for more than 30 days at 4°C without any noteworthy deterioration.

Microbiological evaluation of whole, sliced, and freeze‐dried black truffles (Tuber melanosporum) under vacuum packaging and refrigerator storage

AbstractBackgroundBlack truffle (Tuber melanosporum) is usually available in a form of a whole, offcut pieces (sliced to remove defects or broken from larger truffles) or freeze‐dried (one of the preservation methods), but there is insufficient knowledge about microbial spoilage of these products. The changes in the microbiology of whole, sliced, and freeze‐dried black truffles (Tuber melanosporum) were determined in this study. All truffle samples were vacuum‐packaged and stored at 4°C for 30 days and evaluated on day 0, 4, 8, 15, and 30. The total plate count, Pseudomonas spp. count, yeast, and mold count, as well as the presence of Listeria spp., Salmonella spp., and Bacillus spp., were examined.ResultsThe main finding of this study was that the total microbial count, Pseudomonas spp. count, and yeasts count associated with the freeze‐dried truffles were generally lower than that of the whole and sliced truffles. While mold, Listeria spp., and Salmonella spp. were not detected (<2.00 log CFU/g), Bacillus spp. were detected at a very low count in all sample types (<3.48 log CFU/g).ConclusionOverall, the results suggest the need to establish an effective decontamination treatment before packaging and storage to delay microbial spoilage.

Short UV-C treatments extend the shelf-life of fresh-cut strawberries (Fragaria x ananassa Duch cv. Camarosa)

In recent years there has been a marked increase in the demand for fresh-cut fruit. Although these products have high user convenience, they are extremely perishable. Consequently, they must be marketed within a very short period. A number of studies have shown that brief UV-C irradiation prior to storage may reduce postharvest deterioration in whole fruit. Herein, we evaluated the influence of different UV-C dose and intensity combinations on the quality and shelf-life of fresh-cut strawberries. Fresh berries were cut in wedges and subjected to brief UV-C treatments having different combinations of radiation intensity (0, 9, or 36 W m-2) and dose (0, 2, or 4 kJ m-2). Treatments with a dosage of 4 kJ m-2 at an intensity of 36 W m-2 decreased decay, juice leakage, dehydration softening, and yeasts and mold counts. UV-C treated berries also scored better in freshness color and overall acceptability in consumer tests. The treatments did not affect the acidity, soluble solids, or phenolic compounds. Results suggest that short UV-C treatment could be useful to supplement cold storage, extending the shelf-life of fresh-cut strawberries.

Development and characterization of the nutritional profile and microbial safety of rice-nixtamalized corn grits blends as potential alternative staple for household consumption

The nutritional composition of corn is relatively insufficient to sustain human growth and development. This study developed and characterized rice-nixtamalized corn blends to enhance the nutritional quality of rice-corn composites geared towards household consumption. Corn kernels of two Philippine corn varieties, IPB Var 6 (VK) and Lagkitan (LK), were nixtamalized using ecological method, processed into corn grits, and blended with locally available rice Sinandomeng. Out of the six rice-nixtamalized corn grits blends developed, three blends (30% VK, 70% LK, and 50% VK) were considered most acceptable based on sensory evaluation of consumer panelists. The blends required 210−290 mL cooking water and 20−25 minutes of cooking time. Microbial analysis showed that the blends had <1.0 × 103 cfu/g yeast and mold count (YMC) after two months of storage in a dry place at ambient conditions, indicating food safety upon common short-term storage in a typical Filipino household. Both the IPB Var 6 and Lagkitan blends exhibited significant increase in calcium (2- to 3-folds), iron (4- to 7-folds), zinc, (1- to 2-folds), and phosphorus (1- to 2-folds) as compared to rice alone. Consuming 100 grams of the developed rice-nixtamalized corn grits blends can achieve an average healthy adult's daily calcium requirement by 4%, iron requirement by 7%, and as high as 35% zinc requirement.

Effect of orange peel and moringa leaves extracts on quality of chicken sausages under frozen storage

PurposeThis paper aims to study the effect of orange peel and moringa leaves extracts on microbiological safety, sensory quality, lipid oxidation and color properties of chicken sausages under frozen storage.Design/methodology/approachChicken sausages were prepared by using orange peel, moringa leaves extracts and butylated hydroxytoluene (BHT). The sausages were stored in a freezer at −18°C. Samples were taken at a regular interval of 20 days from the day of production to spoilage of sausages and analyzed for microbiological safety, sensory quality, lipid oxidation and color properties.FindingsIn comparison to the control sausage, sausages having BHT, orange peel and moringa leaves extract had a significantly (p < 0.05) lower bacterial, yeast and mold count. All the sausages were microbiologically safe for consumption till the 100th day, and the results of the 120th day crossed the permissible limits. Sensory acceptability scores of sausages were good (>6) throughout the storage period. The color values of sausages were not affected by the addition of orange peel and moringa leaves extract. The extent of lipid oxidation increased during storage, and sausages with BHT, orange peel and moringa leaves extract had significantly (p < 0.05) lower values of thiobarbituric acid reactive substances and free fatty acids (FFAs) toward the end of the storage period.Originality/valueThe observations of this paper endorse the use of orange peel and moringa leaves extract in meat products formulation for acceptable storage stability under frozen conditions.

Potential of pulsed light treatment to pasteurize pomegranate juice: Microbial safety, enzyme inactivation, and phytochemical retention

The study explores the pasteurization condition of pomegranate juice using pulsed light (PL) treatment within a fluence domain of 312–2988 J cm−2. A 5-log reduction (microbial safety) in Escherichia coli ATCC 43888, aerobic mesophiles, yeasts & molds count in the juice was obtained at 761.4 J cm−2 (2.7 kV for 90 s). The thermal treatment attaining the equivalent lethality was 95 °C for 2 min. A complete inactivation in enzyme activity (polyphenol oxidase and peroxidase) along with microbial safety was attained for the treatments at 2988 J cm−2 (PL) and 95 °C/3 min (thermal treatment). The thermally pasteurized sample (95 °C/3 min) showed 30 and 37% depletion in phenolic compounds and antioxidant capacity, respectively, with only 34% vitamin C in the juice. The equivalent PL pasteurized (2988 J cm−2) juice retained 97%, 94%, and 83% phenolics, antioxidants, and ascorbic acid, respectively. The PL-pasteurized sample's quality attributes and sensory profile were on par with high-pressure and pulsed electric field pasteurized juices from the literature. In turn, PL treatment of the pomegranate juice at 2988 J cm−2 satisfies the criteria for all the stakeholders such as microbial safety (manufacturers demand), enzymatic stability (retailer's demand), and phytochemical retention (consumers demand).

Production and Assessment of Probiotic Fruit Juice from Punjab Pink &lt;br /&gt; Variety of Guava

Probiotics are considered as live microbial formulations exhibiting health benefits related to their ability to alter the gut microbiota and thereby preventing diseases. The present study was conducted to produce probiotic guava juice in a pilot plant (batch type, 50L capacity) through the application of Lactobacillus acidophilus (MTCC no. 10307). The probiotic cells of Lactobacillus acidophilus were added aseptically into the guava juice at 15% (v/v) to reach a concentration of 108–109 CFU/ml and bottling was done using pneumatic bottling unit. The physiochemical (pH, TSS, total sugars [reducing and non-reducing], titratable acidity, antioxidant activity, content of lactic acid and ascorbic acid), microbiological and sensory parameters were analyzed. Among the physiochemical parameters a significant decrease was observed in pH 5.62 to 3.99, TSS from 15.11°brix to 13.45°brix, total sugars from 6.78% to 3.23%, reducing sugar content from 3.46% to 1.62%, non-reducing sugars from 3.32% to 1.60%, content of ascorbic acid from 167.25 mg/100ml to 160.01 mg/100 ml and antioxidant activity from 43.82% to 33.95% except for titratable acidity and lactic acid content which increased significantly during 8 weeks storage under refrigeration. Lactobacillus viability was found to remain well above 8 log CFU/ml for four weeks. Total plate count remained within acceptable limits during the first 5 weeks and yeast and mould count was within satisfactory limits throughout the storage period of 8 weeks. Presence of coliforms was not detected during the storage of 8 weeks. Overall acceptability of probiotic guava juice was 8.56.

Effect of sorghum bran incorporation on the physicochemical and microbial properties of beef sausage during cold storage

Sorghum bran is a rich source of phenolic compounds with potent antioxidant and antimicrobial properties. This study investigated the effect of brown and black sorghum bran incorporation on the physicochemical and microbiological properties of beef sausages during cold storage at 4 °C. Results showed that the incorporation of sorghum bran in sausages, unexpectedly, promoted sausage discolouration, oxidation and pH fluctuation. The addition of sorghum bran in sausages significantly increased the texture values, including hardness, cohesiveness, resilience, gumminess and chewiness. In sorghum-added sausages, the total plate count, yeast & moulds count, and total Coliforms were inhibited only for the first 5–10 days, followed by a rapid increase, whilst the pathogenic Escherichia coli and Listeria spp. were inhibited throughout storage. Brown and black sorghum bran treatments had similar effects on sausages, and the effects were dependent on the amount of bran added. Although this study did not confirm the antioxidant effect of sorghum bran in meat application, it did demonstrate that sorghum bran has some antimicrobial activity, both of which require further evidence for verification. • Sorghum bran addition promoted sausage discolouration, oxidation and pH fluctuation. • Sorghum bran addition enhanced the sausage texture. • Sorghum bran addition showed some antimicrobial activity. • Brown and black sorghum bran showed similar effects on sausage quality.

Spirulina platensis and biosynthesized selenium nanoparticles improve performance, antioxidant status, humoral immunity and dietary and ileal microbial populations of heat-stressed broilers

This study was conducted to assess the impact of dietary incorporation of Spirulina platensis and selenium nanoparticles (SeNPs) individually or in combinations on growth performance, antioxidant status, humoral immune response, and microbial populations in diet and ileum of heat-stressed broilers. Ross-308 one-day chicks (n = 450) were fed one of 9 experimental diets with five replicate cages in 2 phases for 35 d. The experimental diets were a control basal diet without supplementation or with 0.1 mg SeNPs, 0.2 mg SeNPs, 5 g Spirulina, 10 g Spirulina, 0.1 mg SeNPs + 5 g Spirulina, 0.1 mg SeNPs + 10 g Spirulina, 0.2 mg SeNPs + 5 g Spirulina and 0.2 mg SeNPs + 10 g Spirulina per kg diet. Dietary supplementation with Spirulina and SeNPs significantly (P < 0.05) increased body weight gain and European production efficiency factor. Serum GPx and SOD were significantly (P < 0.05) increased with dietary Spirulina and SeNPs supplementation, while, TBARS was decreased (P < 0.05). Circulating immunoglobulin IgM, IgA and IgG were increased in treated birds compared to the control ones, while the antibody titers to IBD, AIV, and NDV were not significantly altered. The results showed that SeNPs and Spirulina exhibited dose-dependent antimicrobial activities against ileal counts of total bacterial, total molds and yeast, coliform, E. coli, Salmonella spp. and Enterococcus spp. However, ileal populations of Lactic acid bacteria were increased with dietary Spirulina and SeNPs in a dose-dependent manner. The microbial load in broilers' diets was reduced by dietary incorporation of S. platensis and SeNPs. These results indicate that Spirulina and SeNPs can be potentially used as growth promoters and antioxidant, immunostimulant, and antimicrobial agents in heat-stressed broilers.

Microbial quality and safety of ready-to-eat street-vended foods sold in selected locations in Kenya

Objectives: Street-vended foods (SVFs) are a major contributor to foodborne diseases, especially in developing countries, where their sale is largely uncontrolled. Foodborne diseases have often been linked to high morbidity and mortality in some developing countries such as Kenya, demonstrating their public health and societal significance. The objective of this study was to determine the microbial quality and safety of ready-to-eat (RTE) foods sold in selected locations within Thika town in Kiambu County, Kenya. Material and Methods: A total of 199 food samples consisting of cereals, sliced fruits, salads, groundnuts, tubers, fruit juices, boiled deshelled eggs, smokies, and sausages were randomly collected for microbial analysis. Determination of total viable count (TVC), total coliform count (TCC), yeast and molds count (YMC), Escherichia coli counts, Staphylococcus aureus counts as well as the presence of Salmonella spp ., and Listeria monocytogenes were determined following standard microbiological methods. Results: Results revealed that plant-based foods had significantly (P &lt; 0.01) higher TVC, TCC, YMC, and S. aureus counts compared to animal-based foods. The levels of TVC, TCC, YMC, E. coli, and S. aureus ranged from 6.590 ± 1.020 to 3.377 ± 1.764, 5.567 ± 2.233 to 1.594 ± 2.299, 5.052 ± 1.201 to 1.595 ± 2.146, 2.033 ± 1.229 to 0.000 ± 0.000, and 5.972 ± 1.170 to 1.888 ± 1.660 Log10 CFU/g, respectively. At least nine food samples were contaminated with E. coli although the chance for contamination was significantly (P = 0.0002) higher (15 times) in plant-based foods compared to animal-based foods. At least one sample in each food type was contaminated with S. aureus with contamination levels above 1.888 ± 1.660 Log10 CFU/g. Salmonella spp. was only detected in boiled arrowroots (25%), boiled deshelled eggs (5.6%), French fries (5.6%), juices (5.0%), and cereals (11.1%), while L. monocytogenes were not detected in any food sample. Conclusion: These findings demonstrate that RTE SVFs sold in this region constitute a potential health hazard to consumers because of the presence of Salmonella spp., and high counts of E. coli and S. aureus. These foods are, therefore, microbiologically unsafe and unsuitable for human consumption as they may cause foodborne disease outbreaks.

Microbial quality and safety of ready-to-eat street-vended foods sold in selected locations in Kenya

OBJECTIVES:Street-vended foods (SVFs) are a major contributor to foodborne diseases, especially in developing countries, where their sale is largely uncontrolled. Foodborne diseases have often been linked to high morbidity and mortality in some developing countries such as Kenya, demonstrating their public health and societal significance. The objective of this study was to determine the microbial quality and safety of ready-to-eat (RTE) foods sold in selected locations within Thika town in Kiambu County, Kenya.MATERIAL AND METHODS:A total of 199 food samples consisting of cereals, sliced fruits, salads, groundnuts, tubers, fruit juices, boiled deshelled eggs, smokies, and sausages were randomly collected for microbial analysis. Determination of total viable count (TVC), total coliform count (TCC), yeast and molds count (YMC), Escherichia coli counts, Staphylococcus aureus counts as well as the presence of Salmonella spp ., and Listeria monocytogenes were determined following standard microbiological methods.RESULTS:Results revealed that plant-based foods had significantly (P &lt; 0.01) higher TVC, TCC, YMC, and S. aureus counts compared to animal-based foods. The levels of TVC, TCC, YMC, E. coli, and S. aureus ranged from 6.590 ± 1.020 to 3.377 ± 1.764, 5.567 ± 2.233 to 1.594 ± 2.299, 5.052 ± 1.201 to 1.595 ± 2.146, 2.033 ± 1.229 to 0.000 ± 0.000, and 5.972 ± 1.170 to 1.888 ± 1.660 Log10 CFU/g, respectively. At least nine food samples were contaminated with E. coli although the chance for contamination was significantly (P = 0.0002) higher (15 times) in plant-based foods compared to animal-based foods. At least one sample in each food type was contaminated with S. aureus with contamination levels above 1.888 ± 1.660 Log10 CFU/g. Salmonella spp. was only detected in boiled arrowroots (25%), boiled deshelled eggs (5.6%), French fries (5.6%), juices (5.0%), and cereals (11.1%), while L. monocytogenes were not detected in any food sample.CONCLUSION:These findings demonstrate that RTE SVFs sold in this region constitute a potential health hazard to consumers because of the presence of Salmonella spp., and high counts of E. coli and S. aureus. These foods are, therefore, microbiologically unsafe and unsuitable for human consumption as they may cause foodborne disease outbreaks.

Mycoflora and Aflatoxin Producing Fungi from Some Storage Cereal Grains Sold in Darki Market, Wudil Local Government Area, Kano State, Nigeria

Aim: The study was aimed at determining the mycoflora and aflatoxin producing fungi in some storage cereals sold at Darki market, Wudil Local Government Area, Kano State. Nigeria.&#x0D; Study Design: A total of thirty samples (ten samples containing 250g each of maize, millet and wheat) were obtained from storage facilities of traders in different location of Darki, market.&#x0D; Place and Duration of Study: Storage facilities of Darki market, Wudil, Kano State, between May 2021 and July 2021.&#x0D; Methodology: Samples were subjected to serial dilution, enumeration of fungal load using pour plate method, inoculation and isolation of fungi using direct plating method, extraction and detection of aflatoxin using thin layer chromatography and molecular analysis using PCR.&#x0D; Result: Total fungal (mold) count on Potato Dextrose Agar recorded the highest count of 6.5103 in wheat sample 4 (WH4) while the least count of 2.2102 was recorded in wheat sample 6 (WH6). The fungal isolates obtained from this study were Aspergillus niger, Aspergillus flavus, Fusarium spp, Mucor spp, and Rhizopus spp. The percentage of occurrence of fungi isolated from the cereal samples was highest in Aspergillus niger (34.43%) and the least (11.48%) was recorded in Mucor spp. Extraction and detection methods revealed a blue fluorescence on the TLC plates indicating the presence of aflatoxin B in the samples. The standard calculated range of Retention factor value was between 0.58 and 0.75. After DNA extraction, the fragment size obtained by PCR reactions with primer pairs ITS1/ITS4 showed 600bp for most of the isolates. All the Aspergillus spp, Fusarium spp. and Rhizopus spp showed positivity for the molecular markers ITS1/ITS4 by having positive bands. Only Mucor spp showed negative results for ITS1/ITS4 primers and showed no band.&#x0D; Conclusion: This study shows that most of the cereals were contaminated with either one or more molds but within the satisfactory and marginal limits. However, aflatoxin contamination is a threatening issue Hence aflatoxins contamination of crops at harvest conditions should be controlled to some extent by the implementation of good agricultural practices and good storage practices.

Changes in Physicochemical, Microbiological and Sensory Properties of Candy Incorporated with Basella Alba upon Storage

ABSTRACT Basella alba (B. alba) is known for health benefits owing to its beneficial phytochemicals. This study aimed to process B. alba leaves into candies which has prolonged shelf life. B. alba candy was analyzed for the physicochemical characteristics like color, pH, titratable acidity, total soluble solid, moisture content, water activity, texture profile analysis. During storage, significant increase in TSS and TA, while a nonsignificant increase in water activity was observed. pH and moisture contents were found to decrease significantly during storage at both ambient and accelerated temperature. Hardness and adhesion of candy showed significant decrease upon storage at both ambient and accelerated temperature. Yeast and mold count of 100 cfu/g suggests that the candies were safe for human consumption during storage at both ambient and accelerated temperature and the desired sensory characteristic of the candy was retained for 28 days at ambient temperature and less than 14 days at accelerated temperature.

Microbiological Evaluation and Molecular Discrimination of Milk Samples from Humans and Different Animals

Milk is a highly nutritious food and it is important to be free of any pathogenic microbes that could be transmitted to humans and affect public health. A total of 145 milk samples were collected from humans and different animal species (cow, buffalo, ewe, goat, camel, mare, and donkey) and underwent physical examination (color, odor, and taste), chemical analysis for its components (water, total salt, fat, protein, lactose, and ash), and finally microbiological (bacteriological and mycological) examinations. Standard plate count, preliminary incubation count, lab pasteurized count, coliform, Escherichia coli, Staphylococcus species, Salmonella species, yeast, and mold counts were measured. PCR test was performed to differentiate milk from different sources (animals and humans) by producing a specific band for each milk type. The results of the physical examination of different kinds of milk showed different grades of white color with the characteristic odor and taste of each milk type. Chemical examination revealed that the highest water content was in donkey milk and the lowest was in buffalo milk while total solids indicated the highest content in sheep milk and the lowest in donkey milk. The microbiological analysis presented that the standard plate count results were the highest in the milk obtained from sheep and camel, while donkey milk was the least in this regard. Yeast counts were the highest in buffalo milk but cow milk was the highest in mold counts. PCR results of milk types using species-specific primers and DNA template extracted from milk somatic cells revealed a specific band for each milk type as 157, 195, 225, 242, 274, and 711 base pair (bp) for goat, human, sheep, buffalo, cattle milk, and camel milk, respectively. It was concluded that more restrictions must be applied to decrease milk contamination as high microbial counts detected in the present study can affect milk quality, public health, and the dairy industry. PCR used in the current work for milk discrimination used milk somatic cells specifically mitochondrial cytochrome b gene which exhibited high specificity in the PCR reactions and this could be served as a cheap and simple method, compared to other types of PCR.

Improved Survival of Freeze-Dried Lactobacillus pentosus SY130 and Applied as a Co-culture Starter with Lactobacillus plantarum KJ03 for Fermenting Stink Bean (Sataw-Dong).

Sataw-Dong, generally produced by spontaneous fermentation of mature stink beans. Monosodium glutamate effectively increases the viability of freeze-dried Lactobacillus pentosus SY130, which is able to inhibit yeast film formation in Sataw-Dong fermentation. For storage stability, the viability of freeze-dried L. pentosus SY130 and Lactobacillus plantarum KJ03, which can reduce the fermentation time of Sataw-Dong depended on storage temperature. Sataw-Dong produced by a co-culture of L. plantarum KJ03 and L. pentosus SY130 showed the highest overall acceptance score in sensory analysis. In addition, plate counts revealed lower counts of yeast and mold, and Enterobacteriaceae in inoculated Sataw-Dong, compared to the spontaneous Sataw-Dong. The main volatile organic compounds in all Sataw-Dong samples was sulfur and ketone groups. The results indicate that using a blend of the freeze-dried co-culture can be successfully used as a starter culture in Sataw-Dong fermentation, and could be further applied with other vegetables to make value-added fermented products.

Instrumental textural properties and sensory acceptability of rehydrated Thai fermented fish dip as affected by addition of Xanthan Gum and modified Tapioca starch

ABSTRACT Instant powder of Thai-fermented fish dip (TFFD), a conveniently used dipping product, fails to form a homogenous viscous paste after being rehydrated. The addition of thickening agents, xanthan gum and hydroxypropyl distarch phosphate from tapioca (HDPT), may resolve this problem. Two sets of instant TFFD samples (5 samples/set) were mixed with five concentrations of xanthan gum (0%, 0.05%, 0.1%, 0.15%, and 0.2%) and five concentrations of HDPT (0%, 0.1%, 0.2%, 0.3%, and 0.4%), respectively. The samples were analyzed for CIE color values (L*, a*, and b*), aw, yeast and mold count (YM), and total plate count (TPC). They were also rehydrated and evaluated for CIE color values, texture profile analysis (TPA) (firmness, consistency, cohesiveness, and viscosity), and sensory scores (homogeneity, color, odor, flavor, mouth-feel texture, and overall acceptability). It was found that the concentrations of both thickening agents did not influence the CIE color values, aw, YM, or TPC of TFFD powder. They also did not affect the CIE color values of rehydrated product. Xanthan gum at 0.1–0.4% improved TPA values (firmness and cohesiveness) and sensory scores (homogeneity, flavor, and overall acceptability) of rehydrated product. HDPT at 0.2% produced no adverse effect on flavor and improved the homogeneity of the product. However, it failed to improve TPA values.

Effect of α-dl tocopherol acetate (antioxidant) enriched edible coating on the physicochemical, functional properties and shelf life of minimally processed carrots (Daucus carota subsp. sativus)

The present study was carried out to investigate the effect of varying sodium alginate-based edible coating (1, 2, and 3 %, w/v) supplemented with α- tocopherol acetate (antioxidant) at different concentrations (0.5 and 1 % w/v) on minimally processed carrot slices during 15 d storage at 10 °C and 65 % relative humidity. Seven different formulations (T1- T7) comprising different alginate and antioxidant combination were tested for selecting the best formulation maintaining the physicochemical attributes, antioxidant potential, carotenoid content, and overall acceptability (microbial counts) of carrot slices. Treatment T4 (2% sodium alginate + 1% α-tocopherol acetate) served as the best formulation in maintaining the quality, acceptability, nutritive value of minimally processed carrots. The T4 treated carrot samples showed minimum variation in weight loss, TSS, pH, whiteness index, reducing sugar, ascorbic acid content, TPC, antioxidant activity, total carotenoids, total aerobic bacterial count and yeast and mold counts, respectively in comparison to other treatments during storage. The statistical analysis also confirmed the significant (p<0.05) variation in physicochemical properties, antioxidant potential, carotenoid content and microbial count in control samples than edible coating formulations during storage.

Novel alkaline phosphatase/lipase-responsive composite hydrogel guar gum/pyruvic acid sodium modified by Zn2+ for mold and yeast biochemical signal exhibition

Zn2+-guar gum/pyruvic acid sodium (named as Zn-GG/PAS) composite hydrogel with chromogenic substrates 5-bromo-4-chloro-3-indolyl phosphate disodium salt (BCIP-2Na) and 4-nitrophenyl palmitate (PNP-PAL) was synthesized by incorporating Zn2+ into guar gum/pyruvic acid sodium composite hydrogel and used for mold and yeast biochemical signal fluorescence and visible exhibition. Zn-GG/PAS exhibited excellent water holding capacity (95%) with a final concentration of Zn2+ of 0.1 g/L. When the concentration of Zn2+ was 0.1 g/L, the cohesiveness and springiness were 0.14 g and 2.9 g, respectively. After GG/PAS with composite ratio of 8/2 (w/w) was added to Zn-GG/PAS, the elasticity modulus and viscous modulus remained relatively stable with the scanning range of viscosity. The cross-linked network of Zn-GG/PAS hydrogel provided an excellent encapsulation efficiency of 94% until 120 h. Compared with the national standard GB 4789.15–2016, the alkaline phosphatase/lipase-responsive Zn-GG/PAS hydrogel had no significant difference in terms of mold and yeast colony count. This work provides a convenient and effective method for fabricating composite hydrogel with alkaline phosphatase and lipase stimulate responsive that has promising application to sensitive exhibition of mold and yeast biochemical signals in microbiological detection.

The Effect of Microwave Irradiation on the Representation and Growth of Moulds in Nuts and Almonds.

Microwave (MW) irradiation is a non-destructive method that can be applied as an alternative method to inhibit the growth of microorganisms. The present study evaluated the effect of MW irradiation on the occurrence of moulds in nuts and almonds. Samples of unshelled natural almonds, pistachios, and in-shell peanuts were treated with different doses of MW irradiation (2400–4000 W). The effect of MW irradiation on mould counts was evaluated by cultivating immediately after irradiation and after 3 and 6 months of storage. The most represented genera in all analysed samples were Aspergillus (68%), Penicillium (21%), and a small amount of Cladosporium (3%). Mould numbers significantly decreased after MW treatment. The treatments with MW irradiations at 3000 and 4000 W significantly reduced the mould colony counts, and their effect persisted during storage; irradiation at 2400 W was partially effective. The strongest effect of MW irradiation was observed in in-shell peanuts. MW irradiation seems to be a promising method for maintaining the microbiological quality of nuts.