Package of the Summer 2021

Background and Objective: Probiotics are dietary supplements with potential health benefits for humans when consumed regularly at appropriate quantities. The latest evidence shows possible beneficial effects of probiotics in COVID-19 treatment. Interests in probiotic consumption have led to provide products such as probiotic juices with vitamins, minerals, prebiotics and appropriate levels of probiotics to the market in free and encapsulated forms, which are not fully addressed in scientific literatures. The objective of this review was to investigate effects of probiotics for the management of human health. Other objectives included study on effects of free and encapsulated forms of probiotics when incorporated in fruit juices on their survivability, storage stability and physiological and functional characteristics in host cells under gastric and intestinal conditions.

Results and Conclusion: Studies have shown that lactobacilli strains are verified strains for producing probiotic supplements, including juices. Various methods have been suggested to improve survivability of probiotics. Encapsulation can protect probiotics against physical characteristics of juices and hence bacterial physiological damages under anaerobic conditions. Several methods have been used to encapsulate probiotics, each of them has shown distinct characteristics. However, further studies on the quality control of probiotic juices are necessary.

Conflict of interest: The authors declare no conflict of interest.

Background and Objective: One of the major sources of Listeria monocytogenes, as the causative agent of invasive listeriosis, is raw milk. The aim of the present study was to detect Listeria monocytogenes in raw milk samples collected from dairy stores in Tehran, Iran, 2019.

Material and Methods: A total of 100 raw milk samples were assessed using cultural techniques. Furthermore, antimicrobial resistance profiles of the Listeria isolates were assessed against eight antimicrobials using disc diffusion method.

Results and Conclusion: Listeria spp., including Listeria grayi (5%), Listeria ivanovii (3%) and Listeria monocytogenes (2%), were detected in 10% of the samples. Listeria monocytogenes isolates were susceptible to major antimicrobials used for the treatment of listeriosis with no multidrug resistances. The highest frequencies of resistance were seen against streptomycin (60%), gentamicin (50%) and tetracycline (50%). In conclusion, potential risks of listeriosis still threaten consumers of the raw milk in Tehran.

Conflict of interest: The authors declare no conflict of interest.

Background and Objectives: Cholesterol hyper-accumulation is a growing factor causing cardiovascular diseases (CVD), a leading cause of global mortality and accounts for 16.7 million deaths worldwide. As far as India is concerned, there is an increase from 25.7 to 54.7 million cases of CVD per year since the year 1990, and change in the dietary pattern being the major cause of this condition. Amongst, coronary heart disease and atherosclerosis remain prominent with its major causative agent as high cholesterol levels. However, the current treatment of these diseases is inadequate, and impose systemic toxicity such as stent thrombosis, chronic inflammation, etc., probiotics with cholesterol-lowering ability is an ideal and safe choice for the prevention of the condition.

Materials and Methods: The present study involved the culture-dependent method for the enumeration of microorganisms from caterpillar frass. Upon microscopic screening, yeast isolates were further characterized for their in-vitro probiotic potential such as toxicity assessment, tolerance to pH, bile, temperature, and salt conditions, safety assessment by measuring antibiotics susceptibility, evaluating antagonistic activity, assessing survival in simulated gastrointestinal environment, measuring aggregation capability, evaluating cholesterol-lowering activity and identifying microorganisms using molecular identification tools. 

Results and Conclusion: The culture-dependent approach resulted in the isolation of four yeast cultures from the frass of Pyrrharctia isabella caterpillar. Yeast cultures designated as CP-I, CP-II, CP-III, and CP-IV were resistant for bile (1.2%), wide range of pH (1.5–10), and up to 42ºC temperature along with antimicrobial activity. CP-I culture also possessed bile salt hydrolase while tolerated stressful salt conditions, gastrointestinal environment, and exhibited good aggregation properties and hydrophobicity. Interestingly, CP-I could reduce cholesterol levels by 9.16% under in-vitro conditions. Molecular identification of CP-I showed its genetic similarity 97% with Saccharomyces cerevisiae. This study demonstrated for the first-time isolation of cholesterol-lowering probiotic yeast Saccharomyces cerevisiae from caterpillar frass in in-vitro conditions.

Background and Objective: Probiotics' effects on harmful oral bacteria have been verifed. As antibiotic resistance becomes a major problem, searching for novel potential species is important. The objective of this study was to select novel safe strains of lactic acid bacteria with potentials as oral probiotics. Furthermore, ability of these strains to suppress growth and attachment of Streptococcus mutans as the most important cariogenic bacteria in tooth decay was investigated.

Material and Methods: Initial identification tests, including Gram staining and catalase and oxidase tests, were carried out on 22 strains of lactic acid bacteria isolated from Iranian traditional dairy products. Safety of the strains was assessed using hemolysis test and antibiotic resistance assessment. Strains were then assessed for probiotic characteristics such inhibition of Streptococcus mutans growth, tolerance to lysozyme enzymes and ability of adhesion as well as ability of decreasing Streptococcus mutans adhesion. Selected strains were identified using16S rRNA molecular method.

Results and Conclusion: Of all strains, four strains with the optimal probiotic characteristics were selected. These included one Lactobacillus brevis, one Lactobacillus casei and two Lactobacillus paraceasei. These four strains showed strong antimicrobial characteristics against Streptococcus mutans, were resistant to oral lysozyme enzymes and included high adhesion abilities to polystyrene wells. Furthermore, they decreased Streptococcus mutans attachment; thus, biofilm formation by this bacterium was prevented. These strains were recognized as safe strains since they were approved in assessments of antibiotic susceptibility and hemolytic activity. Therefore, these four strains are suggested as oral probiotics.

Conflict of interest: The authors declare no conflict of interest.

Background and Objective: Currently, there is a trend towards a healthy lifestyle. Interest in specialty foods is increasing due to the desire for a balanced diet. One of the main food products of the population is bread and bakery products. These products often have an unbalanced composition. Therefore bakery products are enriched with easily digestible and bioavailable free amino acids and peptides to increase the nutritional value. This study aims to develop new types of bakery products using the mechanoenzymatic hydrolysis technology and assess their quality.

Material and Methods: A distinctive feature of the study was that the production line involved mechanical pretreatment of the biomass in the presence of the enzyme. Mechanical pretreatment of pea seeds without adding the enzyme product (when the enzymes were added immediately before the hydrolysis and did not undergo mechanical treatment) reduced the hydrolysis rate almost twofold compared to that in the system “biomass + enzyme treated simultaneously.” A complex enzyme product Protosubtilin G3x exhibiting protease, xylanase, β-glucanase, and pectinase activities was used for hydrolysis of biomass.

Results and Conclusion: The optimal hydrolysis parameters (enzyme concentration and duration of the process) were determined. The finished hydrolysate of the mechanically treated pea seed biomass was added to dough to enrich bakery products with macro- and micronutrients. The sponge-and-dough method was the optimal dough mixing method according to a combination of sensory and physicochemical parameters. Quality parameters of the pre-ferment depending on yeast and hydrolysis contents was assessed using mathematical modeling. Regression equations were derived to predict the formation of water-soluble substances during fermentation of the dough semi-finished product. The action of the selected enzyme was found to be efficient as the finished products were enriched in free amino acids, while the protein content was reduced. The finished products were classified as functional food products due to the optimal content of minerals and vitamins. The new products are recommended to be included in the diet of people allergic to legume proteins and healthy individuals to increase the digestibility of plant-based proteins.

Background and Objective: Variability of foodborne pathogens plays important roles in microbial risk assessment. In the present study, kinetic behaviors of seven Listeria monocytogenes and two Listeria innocua strains from various sources were assessed at various pH (4.5, 5.0, 5.5, 6.8 and 7.0) and salinity (0.5, 2.5, 3.5, 5, 7 and 10% NaCl).

Material and Methods: Maximum specific growth rates (µ_max) were assessed using Bioscreen C (time-to-detection method). Nearly 1500 curves were produced for Listeria monocytogenes and Listeria innocua strains and secondary models were developed for the bacteria as a function of NaCl, pH, temperature and undissociated lactic acid concentrations.

Results and Conclusion: Variability of µ_max enhanced as the growth environment became unfavorable. Coefficient of variation of µ_max in Listeria monocytogenes strains were 6.5 and 20% at 0.5 and 7.5% NaCl (pH 7.26), respectively. After selecting the most robust strain, models demonstrating relationships between the growth rate and environmental conditions (NaCl, pH and undissociated form of lactic acid) were generated using Origin 2018 Software and polynomial and nonlinear surface fitting. In conclusion, intraspecies variability of the growth kinetic behaviors and developed models based on the worst case (e.g., the most robust Listeria monocytogenes strain) include important uses in food industries.

Conflict of interest: The authors declare no conflict of interest.

Background and Objective: Discarded as wastes, parts of the agricultural products can be used for feed productivity as well as management of animal feed production. Production of various products is possible using appropriate processing. The objective of the present study was to use laccase of Albifimbria viridis in degradation of agricultural residues and to produce compounds with herbicide properties.

Material and Methods: The fungi were isolated from agricultural soils. The isolates were identified using morphological detection and PCR amplification of the internal transcribed spacer. Supernatants were collected from semi-solid cultures and laccase activity was assessed using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) substrate. This was carried out using n-hexane and degradation of the agricultural residues was investigated using gas chromatography-mass spectrometry.

Results and Conclusion: Growth of the fungal isolate in culture media with tannic acid was studied using scanning electron microscopy. In total, the isolate produced 50 U ml^-1 laccase. Gas chromatography-mass spectrometry analyses revealed production of oxime, methoxy-phenyl and 2-cyclopenten-1-one for tannic acids, o-guaiacol, tetradecane, hexadecane, octadecane, octadecanoic acid, hexadecanoic acid and benzene, 1,3-bis(1,1-dimethylethyl) for sorghum seeds and 2-acetyl-5-methylfuran, phenol, 2-methoxy and benzene, 1,2-dimethoxy for wheat straw during fungal growth (0.73 mg ml^-1). Results have shown that the laccase enzyme produced from Albifimbria viridis native strain is capable of hydrolytic cleavage of chemical pollutants from agricultural wastes for herbicide bioremediation.

Conflict of interest: The authors declare no conflict of interest.

Background and Objective: Monascus purpureus can produce pigments with light yellow to dark red colors. It includes several health properties. In this study, a low-cost process has been developed for the production of natural pigments from filamentous fungi through solid-state fermentation using cheap substrates.

 Material and Methods: In this study, cultivation conditions were optimized for the production of red Monascus pigment by Monascus purpureus ATCC16362 using response surface methodology. Incubation time (7-24 days), date waste syrup concentrations (1-69%) and NaCl contents (7-13.75 g.l^-1) were analyzed base on central composite design.

Results and Conclusion: The maximum production of red Monascus pigment (5.10 AU.g^-1) by Monascus purpureus was achieved using 55% date waste syrup concentration, 7 g.l^-1 NaCl and incubation time of 21 days. At optimum conditions, µ_max of 6.2 × 10^-3 (mg.g^-1.h^-1), pigment efficiency of 0.238 (AU.g^-1.day^-1), conversion factor of biomass in red pigments of 0.25 (AU.mg^-1.g^-1), glucose utilization of 93% were achieved. Results showed that use of date waste syrup and wheat straw as substrates were successful in solid state cultivation for the production of red pigments by Monascus purpureus.

Conflict of interest: The authors declare no conflict of interest.