Fermentation of table cream by Lactobacillus plantarum strains: effect on fungal growth,aflatoxin M1 and ochratoxin A

Aflatoxin M1 (AFM₁) and ochratoxin A (OTA) are two main mycotoxins in milk and dairy products. In the present work, the ability of four Lactobacillus strains (L. plantarum PTCC 1058, L. plantarum LP3, L. plantarum AF1 and L. plantarum LU5) to remove AFM1 and OTA in fermented cream was studied during 24 h fermentation. The antifungal activity of the mentioned lactobacilli against the defined fungi (Aspergillus flavus PTCC 5004, Aspergillus parasiticus PTCC 5018, Aspergillus nidulans PTCC 5014, Aspergillus ochraceus PTCC 5060) was also evaluated. The results showed that the cell counts of all strains were increased by 64–70% during fermentation. All Lactobacillus strains decreased the amount of AFM₁ significantly (P ≤ 0.05) in the range of 26–52%, which the highest AFM₁-reducing effect was related to L. plantarum LU5 (from 0.5 to 0.24 μg kg⁻¹). The mean OTA removal by Lactobacillus strains in fermented cream also ranged from 32 to 58%. Amongst Lactobacillus strains, the cell-free culture supernatants of L. plantarum LU5 showed the highest (inhibition zone of 26.7 ± 1.2 mm) and L. plantarum LP3 and L. plantarum PTCC 1058 the lowest antifungal activities. The fermented creams contained Lactobacillus strains exhibited the highest and lowest antifungal activities against A. ochraceus and A. parasiticus, respectively. L. plantarum LU5, with the inhibition zone of 27.6 ± 0.9 mm, was the most effective fungal inhibitor, while L. plantarum PTCC 1058 had the lowest antifungal activity.     

Production of propionic acid in a fermented dairy beverage

A dairy beverage containing propionic acid was produced using the adjunct starter cultures with Lactobacillus acidophilus and Propionibacterium freudenreichii ssp. shermanii. The impacts of temperature (30, 35 and 40 °C) and inoculation ratio (1:2, 1:4 and 1:8) on propionic acid production and viability of micro‐organisms were studied. The incubation temperature had a significant adverse (P < 0.05) effect on the viability of P. freudenreichii and propionic acid production. Maximum amount of produced propionic acid (in 1:4–30 °C treatment) was 0.77%w/w. P. freudenreichii and L. acidophilus counts remained high (9 × 10⁶ and 1.5 × 10⁶ cfu/mL, respectively) after cold storage.     

Effect of pulsed ultrasound treatment compared to continuous mode on microbiological and quality of Mirabelle plum during postharvest storage

The effects of pulsed and continuous ultrasound treatment on microbiological and physiological quality of Mirabelle plum fruit were investigated. Freshly harvested Mirabelle plum was treated with 30‐kHz pulsed and continuous ultrasound at 20 °C for 0, 15, 30, 45 and 60 min and subsequently stored at 4 °C for 10 days. The total count of bacteria, total fungi, decay index, titratable acidity (TA), total soluble solids (TSS), colour, texture, ascorbic acid content and total phenolics was measured. The results showed that pulsed and continuous ultrasonic treatment significantly (P < 0.05) reduced the number of microorganisms and improved the quality of Mirabelle plums during storage. Increasing pretreatment time enhanced the positive effects of pulsed and continuous ultrasound. Also, in terms of the total count of bacteria, total fungi, titratable acidity and total phenolics, the pulsed and continuous ultrasound did not show a significant difference (P < 0.05). However, pulsed ultrasound was better compared to continuous mode in preservation of TSS, colour, texture and ascorbic acid content of the fruit during storage. Our results demonstrated that pulsed ultrasound is an appropriate method for improving safety and maintaining the quality of Mirabelle plum fruit.     

Stabilisation mechanism of various inulins and hydrocolloids: Milk–sour cherry juice mixture

Milk–fruit juice mixtures, such as the mainly acidic nutraceutical soft drinks, usually suffer from phase separation due to aggregation of caseins at low pH. In this study, short‐chain inulin (SCI), native inulin (NI), long‐chain inulin (LCI) and a combination of long‐ and short‐chain inulins (LCI:SCI) (MIX) in different ratios (20:80, 50:50 and 80:20) were added (up to 10% w/v) to a milk–sour cherry juice mixture and their stabilisation mechanisms investigated using rheological, microstructural and zeta potential observations. In addition, gum tragacanth (GT) and Persian gum (PG) as adsorbing and guar gum (GG) as nonadsorbing hydrocolloids were combined with inulin to enhance their stabilising properties. Finally, sensory analyses were carried out on the stabilised samples. According to our findings, LCI fully stabilised the mixture (8% w/v), while LCI: SCI and NI only reduced phase separation at very high concentrations, and SCI had no significant effect on the stabilisation. Moreover, no inulin aggregates and rheological changes were observed with SCI. However, LCI, LCI: SCI and NI formed inulin aggregates and the mixtures became even more viscous and thixotropic (LCI > LCI: SCL > NI). Based on these observations, it can be concluded that chain length and concentration are two important factors that affect the functionality of inulin. On the other hand, the combination of inulin with GT and PG did not have any pertinent effect on the stabilisation. However, the mixture of inulin and GG could stabilise the mixtures at certain ratios and concentrations. Furthermore, in mixtures containing GG and SCI, GG played the main role in the stabilisation by increasing the viscosity and forming gel network.     

Bimetal cup hydroforming of Al/St and Cu/St composites: Adaptive finite element analysis and experimental study

Journal of Mechanical Science and Technology - An adaptive Finite element analysis (FEA) was proposed in this paper for the industrial design of bimetal conical-cylindrical cup hydroforming....     

Investigation of synergistic effect of nano sized Ag/TiO2 particles on antibacterial,physical and mechanical properties of UV-curable clear coatings by experimental design

The synergistic effect of nano titanium dioxide (10 and 30 nm) and nano silver (10 nm) as antibacterial agents were investigated on UV curable clear coating. Antibacterial and physical–mechanical properties of coating were optimized using experimental design in response surface method. Twenty different samples of nano Ag and nano TiO₂ were prepared in this method. Antibacterial properties on Gram-negative bacteria (Escherichia coli) were investigated. The results revealed that using equal amounts of two sizes of nano TiO₂ promote the antibacterial activity of nano Ag. So, the coating shows strong activity against E. coli. Physical–mechanical properties such as surface hardness, abrasion resistance, scratch resistance and gloss of the coating were evaluated. The results depicted appropriate physical–mechanical properties. Also, scanning electron microscope (SEM), atomic force microscope (AFM) and Fourier transform infrared (FT-IR) spectroscopy were used to study the effect of nano particles on coating properties.     

Geoenvironmental assessment of the formation and expansion of earth fissures as geological hazards along the route of the Haram-to-Haram Highway,Iran

This study assessed the mechanisms and agents that have contributed to the formation and expansion of earth fissures along the route of the Haram-to-Haram Highway in Iran. To this end, several geological and geotechnical approaches were used, including comprehensive field investigations, in situ tests, soil sampling, and laboratory assessments. Results showed that a combination of shallow and deep mechanisms and various geoenvironmental agents contributed to fissure formation and expansion in the study area, with soil characteristics playing a significant part in the fissuring. This study indicated that earth fissuring is an ongoing problem in the study area that endangers the safety of highway traffic. However, some applicable remedial measures that could mitigate the problem and protect the highway from the adverse consequences of the earth fissuring are also proposed herein.