Non-thermal plasma as a new food preservation method, Its present and future prospect

      Atmospheric pressure plasma (APP) is an emerging non thermal technology for the improvement of food  safety. Non-thermal plasma (NTP) is a neutral ionized gas that comprises highly reactive spices including, positive ions, negative ions, free radicals, electrons, excited or non excited molecules and photons at or near room temperature. NTP can be generated at atmospheric pressure that makes it more applicable. Moreover, it could be employed in inactivation of microorganisms on the surface of fresh and processed foods. However, for the reason that there are few studies on the application of this technology in real food systems, the effects of non-thermal plasma on nutritional and chemical properties of food is not known well. Furthermore, the studies which explore the safety and cost aspects of this technology could help it become widespread in food industry. This paper will attempt to provide a review of atmospheric pressure cold plasma, its application in microbial inactivation,food preservation and future prospect of this new technology.

Occurrence of Bacillus cereus in beef burger marketed in Tehran, capital of Iran

Introduction: Beef burgers made in Iran contain various compounds such as meat, cereals flour, as well as some spices which can be contaminated with Bacillus cereus, causing gastroenteritis in the consumer. This study is focused on occurrence of B.cereus in beef burgers marketed in Tehran, capital of Iran. Methods and Results: In this cross-sectional study, a total of 80 samples of different types of beef burgers marketed in Tehran, Iran were randomly collected based on their percentage of meat content, including 30% (n=25), 60% (n=40) as well as 90% (n=15). The samples were analyzed microbiologically by routine culture assay and biochemical tests to find B.cereus. Data were analyzed statistically by Microsoft Office Excel 2010.  Twenty-five out of 80 (31.25%) beef burger samples were contaminated by B. cereus. Based on the percentage of meat content in the samples, the beef burger with 90% meat were significantly (p<0.05) more contaminated than the others. Also, the contamination rate was significantly (p<0.05) higher in summer compared to winter. Conclusion: This survey showed that the beef burgers supplied in Iran markets is main source of B.cereus that can cause disease in Iranian consumers. More attempts must be focused on cold-chain maintenance in production, distribution, and storage of the meat products

Antibiofilm Effects of Lactobacilli against Ciprofloxacin-Resistant Uropathogenic Escherichia coli strains in Pasteurized Milk

Background and Objective: Uropathogenic Escherichia coli-induced urinary tract infections are the most common uropathogenic Escherichia coli etiological agent. In addition, most of biofilms created by these bacteria can be regarded as a serious problem in the food industry. Foodborne diseases have always been considered an emerging public health concern throughout the world. Many outbreaks have been found to be associated with biofilms. Thus, the aim of the present study is to investigate the anti-adhesive effects of lactic acid bacteria against strains of Ciprofloxacin-Resistant Uropathogenic Escherichia coli using microbial techniques in pasteurized milk.Material and Methods: In this study, strains of Lactobacillus plantarum, Lactobacillus casei and Lactobacillus acidophilus were provided from Pasteur Institute of Iran. Twenty strains of Uropathogenic Escherichia coli-Induced Urinary Tract Infections were isolated from patients with urinary tract infection in Shahid Labbafinejad hospital of Iran. Eight strains with ability of biofilm formation were selected for microbial tests. All of these eight strains were resistant to ciprofloxacin. Disk diffusion method was used to assess the susceptibility of all isolates to the ten common antibiotics. Eight samples of Uropathogenic Escherichia coli were inoculated in pasteurized milk. The microtitre plate 100 method was used to detect anti-adhesive activity of lactobacilli supernatant.Results and Conclusion: Results showed that the eight human isolates were resistant to antibiotics. Isolate of number 4 was the most susceptible strains to antibiofilm effects of lactobacilli in the pasteurized milk. The anti-adhesive effects of lactobacilli on Uropathogenic were confirmed in all microbial tests. In this study, Lactobacillus plantarum revealed the highest inhibitory activity against Uropathogenic Escherichia coli 4 strain with inhibition zones of 42 mm. This strain was reported as a proper probiotic bacterium. According to the results, these lactobacilli have had spectacular effects on biofilm formation and pathogenicity of Uropathogenic strains to prevent the adhesion.Conflict of interest: The authors declare no conflict of interest

Antibacterial Efficacy of Essential Oils and Sodium Nitrite in Vacuum processed Beef Fillet

 Background and Objective: Minimizing the exposure to nitrate and nitrite and therefore reducing the level of potentially carcinogenic nitrosamines is desired due to the strong public demand and political controversy around this issue in many countries. The present study was designed to investigate antibacterial activity of five different types of essential oils alone or in combination with different concentrations of sodium nitrite.Material and Methods: Five types of essential oils Zataria multiflora Boiss, Satureja bachtiarica Bunge, Rosmarinus officinalis L., Mentha pulegium, and Origanum vulgare L were used in the experiments. NaNO2 in concentrations of 0, 100, and 200 mg kg-1 were used to study the growth inhibition of Clostridium spp. inoculated in vacuum processed beef fillet. Essential oils were analyzed by gas chromatography-mass spectrometry. Antimicrobial activity against vegetative cells of Clostridium perfringens and Clostridium sporogenes were primarily done by disc diffusion method and minimum inhibitory concentration of essential oils against vegetative cells were determined by broth macro dilution. Sensory evaluation of the uninoculated cooked vacuum processed beef fillet samples with three essential oils with higher antibacterial activity against the more resistant Clostridium spp. was done.Results and Conclusion: Among the examined Essential oils Satureja bachtiarica Bunge showed the most inhibition effect on Clostridium perfringens (4.1 mg ml-1) and Clostridium sporogenes (5.5 mg ml-1) followed by Zataria multiflora Boiss, Origanum vulgare L., Mentha pulegium and Rosmarinus officinalis L. The antimicrobial activity of essential oils against Clostridium spp. was increased in combination with sodium nitrite. It can therefore be assumed that the combination of these two additives could have significant repercussion in the control of Clostridium perfringens and Clostridium sporogenes in vacuum processed beef fillet samples without compromising the organoleptic properties. The best result was achieved by the combination of 100 mg kg-1 sodium nitrite and 1.1 %v w-1 Satureja Bakhtiarica Bunge which could inhibit the growth of Clostridium species. The results of the current study showed that the essential oils of interest have had drastic effects on clostridium inhibition and could be used in the meat industry especially for sausages due to their impact on technological, microbiological and sensory properties.Conflict of interest: The authors declare no conflict of interest

Assessment of Phenolic Contents and Antioxidant and Antibacterial Activities of Extracts from Four Varieties of Iranian Date Palm (Phoenix dactylifera L.) Seeds

  Background and objective: Every year, large quantities of date palm seeds are produced as byproducts in date processing and packaging industries, which is discarded or used as low-value materials for animal feeds and composts. However, these bioresources may include potentials to produce high-value added products in food industries. The major aim of the current study was to assess phenolic profiles and contents and antioxidant and antibacterial activities of four Iranian date palm seed extracts, namely Zahedi, Kabkab, Mazafati and Rabbi.Material and methods: Total phenolic contents, phenolic compounds profile and antioxidant and antibacterial activities of extracts from four Iranian date palm seeds were assessed using Folin-Ciocalteu, reversed-phase high-performance liquid chromatography, 2, 2-diphenyl-1picrylhydrazyl radical scavenging, agar disc diffusion and broth microdilution methods, respectively.Results and conclusion: Total phenolic contents varied 1480-3380 mg GAE 100 g-1 dw. cinnamic, chlorogenic, caffeic and 3, 5-dihydroxybenzoic acid included the primary phenolic compounds, respectively. Of the varieties, Kabkab and Mazafati seed extracts with IC50 values of 16.56 and 22.6 µg ml-1 demonstrated the highest and lowest radical scavenging activity, respectively. Results obtained from disc diffusion method revealed that all extracts included inhibitory effects against Staphylococcus aureus, but not against Escherichia coli. Minimum inhibitory concentration and minimum bactericidal concentration of the extracts ranged 1.563.125 and 3.125-12.5 mg ml-1 for Staphylococcus aureus, respectively. Based on the findings, Iranian date seeds are good sources of extractable phenolic compounds with notable antioxidant activities, which can be used as natural additives in formulations of various products such as functional foods and dietary supplements. Furthermore, these seeds can be converted to value added products through biotechnological processes.Conflict of interest: The authors declare no conflict of interest.   

Utjecaj esencijalnog ulja biljke Echinophora platyloba i primarnog kondenzata dima na suzbijanje rasta bakterije Staphylococcus aureus u goveđem mesu

In the current study, the antibacterial effect of Echinophora platyloba essential oil and common liquid smoke (individually and in combination) against Staphylococcus aureus in beef meat samples is investigated. Using an automated microbiological growth analyser and the turbidimetric technique, the minimum inhibitory concentrations (MIC) and the minimum bactericidal concentrations (MBC) of the essential oil and liquid smoke were determined. Anti-S. aureus activity of essential oil and liquid smoke (individually and in combination) was defined by disk diffusion assay, generation time and cell constituent release. Apart from that, the interactions between these two compounds were measured by the checkerboard assay and by calculating the fractional inhibitory concentration (FIC) indices. Related MIC values of essential oil and smoke were found to be 7200 and 5500 mg/L, and MBC values were 8500 and 8000 mg/L, respectively. The conducted organoleptic assay showed that the addition of 0.05 g of essential oil and 0.6 g of liquid smoke to 100 g of meat samples did not have adverse effect on the overall acceptance. Weaker antibacterial effect against Staphylococcus aureus was observed when only Echinophora platyloba essential oil was used than when it was used in combination with liquid smoke.U radu je ispitan pojedinačni i zbirni učinak esencijalnog ulja biljke Echinophora platyloba i primarnog kondenzata dima na suzbijanje rasta bakterije Staphylococcus aureus u uzorcima goveđeg mesa. Pomoću automatskog sustava za detekciju mikrobiološkog rasta i turbidimetrije određene su minimalna inhibicijska koncentracija i minimalna baktericidna koncentracija esencijalnog ulja i primarnog kondenzata dima. Pojedinačni i zbirni antibakterijski učinak esencijalnog ulja i primarnog kondenzata dima ispitani su disk difuzijskom metodom, određivanjem generacijskog vremena i mjerenjem apsorbancije otpuštenog staničnog sadržaja bakterije Staphylococcus aureus. Osim toga, ispitana je interakcija između ta dva antimikrobna agensa mikrorazrjeđenjem u bujonu (tzv. checkerboard testom) i određivanjem indeksa interakcije. Minimalna inhibicijska koncentracija esencijalnog ulja bila je 7200 mg/L, a primarnog kondenzata dima 5500 mg/L, dok je minimalna baktericidna koncentracija esencijalnog ulja bila 8500 mg/L, a primarnog kondenzata dima 8000 mg/L. Ispitana su organoleptička svojstva uzoraka mesa i utvrđeno je da dodatak 0,05 g esencijalnog ulja i 0,6 g kondenzata dima u 100 g uzorka nije utjecao na prihvatljivost proizvoda. Esencijalno ulje biljke Echinophora platyloba imalo je slabiji učinak na suzbijanje rasta bakterije Staphylococcus aureus od kombinacije esencijalnog ulja i primarnog kondenzata dima

Postupci proizvodnje propionske kiseline, dosadašnje spoznaje i mogućnosti

During the past years, there has been a growing interest in the bioproduction of propionic acid by Propionibacterium. One of the major limitations of the existing models lies in their low productivity yield. Hence, many strategies have been proposed in order to circumvent this obstacle. This article provides a comprehensive synthesis and review of important biotechnological aspects of propionic acid production as a common ingredient in food and biotechnology industries. We first discuss some of the most important production processes, mainly focusing on biological production. Then, we provide a summary of important propionic acid producers, including Propionibacterium freudenreichii and Propionibacterium acidipropionici, as well as a wide range of reported growth/production media. Furthermore, we describe bioprocess variables that can have impact on the production yield. Finally, we propose methods for the extraction and analysis of propionic acid and put forward strategies for overcoming the limitations of competitive microbial production from the economical point of view. Several factors influence the propionic acid concentration and productivity such as culture conditions, type and bioreactor scale; however, the pH value and temperature are the most important ones. Given that there are many reports about propionic acid production from glucose, whey permeate, glycerol, lactic acid, hemicelluloses, hydrolyzed corn meal, lactose, sugarcane molasses and enzymatically hydrolyzed whole wheat flour, only few review articles evaluate biotechnological aspects, i.e. bioprocess variables.U posljednje je vrijeme porastao interes za biološku proizvodnju propionske kiseline s pomoću bakterije Propionibacterium. Glavni nedostatak postojećih modela je slab prinos, zbog čega su predložene različite strategije rješavanja tog problema. U ovom su radu opsežno prikazana bitna biotehnološka obilježja postupaka dobivanja propionske kiseline, jednog od uobičajenih sastojaka u prehrambenoj i biotehnološkoj proizvodnji. U prvom dijelu opisujemo najznačajnije proizvodne procese, s naglaskom na biološku proizvodnju, a zatim navodimo bakterije koje proizvode propionsku kiselinu, kao što su Propionibacterium freudenreichii i Propionibacterium acidipropionici, te različite podloge za rast ili proizvodnju. Osim toga, opisujemo varijable procesa koje mogu utjecati na prinos. Naposljetku, predlažemo metode ekstrakcije i analize dobivene propionske kiseline, te ističemo strategije pomoću kojih se mogu zaobići ekonomska ograničenja procesa uzrokovana kompeticijom mikroorganizama tijekom proizvodnje. Na koncentraciju propionske kiseline i produktivnost procesa utječe više čimbenika, kao što su: sastav podloge, tip i veličina bioreaktora te pH-vrijednost i temperatura kao najvažniji čimbenici. Objavljen je velik broj radova o proizvodnji propionske kiseline iz glukoze, permeata sirutke, glicerola, mliječne kiseline, hemiceluloze, hidrolizirane sačme kukuruznih klica, laktoze, melase šećerne trske, te brašna od cjelovitog zrna pšenice hidroliziranog pomoću enzima, ali vrlo mali broj revijalnih prikaza procjenjuje biotehnološke aspekte proizodnje, odnosno varijable bioprocesa