ISOLATION AND PARTIAL CHARACTERIZATION OF A NOVEL BACTERIOCIN PRODUCED BY LACTOCOCCUS LACTIS SSP. LACTIS MC38

This work presents the isolation and partial characterization of a new lactococcal bacteriocin produced by Lactococcus lactis ssp. lactis MC38. The bacteriocin demonstrated broad spectrum of inhibition activity against both pathogenic and food spoilage organisms, and various lactic acid bacteria. This antimicrobial substance appeared to be proteinaceous because its activity was completely inactivated by proteinase K and α‐chymotrypsin. It was heat and pH stable. The apparent molecular mass of the purified bacteriocin, determined by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, was 8.0 kDa. The amino acid composition of the studied bacteriocin was found to be quite different from known lactococcal bacteriocins. The calculation of the number of amino acid residues in the bacteriocin molecule revealed that it contained 62 amino acids.     

Purification and partial characterization of antilisterial bacteriocin produced by Pediococcus pentosaceus KJBC11 from Idli batter fermented with Piper betle leaves

Bacteriocins are natural antimicrobial agents mainly act against closely related bacteria and at times unrelated organisms including various food spoilage and pathogenic organisms. Bacteriocins from Lactic Acid Bacteria (LAB) have been widely used for food preservation because of their safety nature. In this study, bacteriocin from Pediococcus pentosaceus KJBC11 was purified with the recovery of 15%, using cell adsorption‐desorption technique, gel permeation chromatography, hydrophobic interaction chromatography, and reversed phase HPLC successively. Molecular weight of bacteriocin KJBC11 was determined to be 4.5 kDa using Tricine SDS‐PAGE. The bacteriocin KJBC11 showed strong inhibitory activity against various Gram‐positive and Gram‐negative pathogens. Bacteriocin KJBC11 activity was not altered when treated with amylase, lipase, and trypsin but inactivated by protease and proteinase enzyme treatment. It was heat stable (100°C, 1 hr) and exhibited strong antimicrobial activity within the pH 3–7. Its mode of action was bactericidal in nature as revealed against Listeria monocytogenes showing leakage of internal contents out of the cell. Bacteriocin KJBC11 could belong to Class IIa‐pediocin like bacteriocins based on its characteristics as well as the presence of pediocin gene in the genome of the isolate KJBC11.

Practical applications

Studies on Lactic Acid Bacteria and bacteriocin have attracted increasing attention for a long time, due to their established role in food fermentation and preservation. The antimicrobial properties of bacteriocin became a trademark approach to achieve food safety and to counter the menace of antibiotic resistant pathogens. This study revealed a potent bacteriocin with wide range of antibacterial activity against various foodborne and clinically important pathogens to have potential application in food preservation and biomedicine.     

Novel chromatographic separation — The potential of smart polymers

‘Smart’ or stimuli-responsive polymers represent new classes of materials that are currently under development. These novel polymeric materials undergo conformational rearrangement in response to small changes in their environment, such as temperature, pH, UV irradiation, ionic strength or electric field. These environmental changes alter the structure of stimuli-responsive polymers and increase or decrease their overall hydrophobicity, resulting in reversible collapse, dehydration or hydrophobic layer formation. With further research into their synthesis, behaviour and application, these novel materials have great potential to become the ‘next generation’ of separation media for cost-effective and environmentally-friendly extraction and purification of high value biomolecules from agri-food and other raw materials.Industrial relevanceThe growing demand for functional food ingredients is requiring the development of selective, cost-effective isolation techniques. Chromatography is one technique employed to produce novel food ingredients. Chromatography procedures often require the use of large quantities of solvents, which must be removed from food products, increasing processing input costs (solvent and energy), and creating an environmental disposal issue. Smart polymers are novel materials that change phase with temperature or other types of operational conditions, and have the potential to offer a cost and environmentally attractive means of producing functional food ingredients. This paper presents a review of smart polymers as novel separation media, and their potential application in the food industry.     

Development of Wide-Spectrum Hybrid Bacteriocins for Food Biopreservation

The food industry demands new procedures and methods to produce minimally processed, ready to eat food with intact nutritional, taste, and flavor properties. The biopreservation and the use of both bacteriocins produced by lactic acid bacteria (LAB) and bacteriocinogenic strains as an alternative to substitute chemical antimicrobial for food preservation became increasingly important in the last two decades. When the new proposed natural preservatives techniques are applied, probiotics food can be obtained and, simultaneously, foodborne pathogens and spoilage contaminants can diminish. However, bacteriocins produced by LAB have a narrow antibacterial spectrum and are inactive against Gram-negative bacteria like Salmonella and the emergent enterohemorrhagic Escherichia coli. Knowing the mechanism of action and the structural features of microcins synthesized by Gram-negative bacteria and with potent antimicrobial activity against the mentioned microorganism, the proposal is to obtain hybrid peptides (microcin–bacteriocin) with broad antimicrobial spectrum. This review explains how the inability of bacteriocins to cross the outer membrane of Gram-negative bacteria unable them to act on the bacteria. It will also be discussed how a hybrid bacteriocin can be obtained.     

Eco-innovative technologies for extraction of proteins for human consumption from renewable protein sources of plant origin

BackgroundThe need for renewable and sustainable sources of proteins is growing. Diets containing more plant protein are increasing due to several reasons: the negative environmental impacts of animal protein production, the increasing vegetarianism and veganism trends, and inadequate consumer acceptance of food grade insects.Scope and approachThis paper links the isolation of valuable proteins from sustainable sources – by-products from processing industry of plant origin and eco-innovative technologies which are emerging for this purpose (electrostatic separation, subcritical water extraction, reverse micelles extraction, aqueous two-phase systems extraction, enzyme-, microwave-, ultrasound-, pulsed electric energy- and high pressure-assisted extraction). In this way, not only the key challenges of modern food processing are met-the assurance of cost-effective, sustainable and environmentally friendly production, but also the concept of zero food waste seems more achievable.Key findings and conclusionsA number of different techniques have emerged with high potential to assist protein extraction of preserved techno-functional properties, but they are still in the early stage of its industrial applications. In the EU, its industrial application may be hindered by legislative issues. The respective Novel Food Regulation classifies food obtained in a production process not used for food production before 15 May 1997, as “novel food’’ and the regulatory status for each single case must be sought. On the other hand, the utilization of novel processing technologies is regulatory encouraged in EU due to their potential to reduce the environmental impact of food production, enhance food security and bring benefits to consumers.     

Bacteriocins as food preservatives: Challenges and emerging horizons

ABSTRACT

The increasing demand for fresh-like food products and the potential health hazards of chemically preserved and processed food products have led to the advent of alternative technologies for the preservation and maintenance of the freshness of the food products. One such preservation strategy is the usage of bacteriocins or bacteriocins producing starter cultures for the preservation of the intended food matrixes. Bacteriocins are ribosomally synthesized smaller polypeptide molecules that exert antagonistic activity against closely related and unrelated group of bacteria. This review is aimed at bringing to lime light the various class of bacteriocins mainly from gram positive bacteria. The desirable characteristics of the bacteriocins which earn them a place in food preservation technology, the success story of the same in various food systems, the various challenges and the strategies employed to put them to work efficiently in various food systems has been discussed in this review. From the industrial point of view various aspects like the improvement of the producer strains, downstream processing and purification of the bacteriocins and recent trends in engineered bacteriocins has also been briefly discussed in this review.     

Microbial diversity changes in soybean sprouts treated with enterocin AS-48

Seed sprouts may act as vehicles for foodborne pathogenic bacteria. In the present study, the effect of washing treatment with the enterococcal bacteriocin enterocin AS-48 on the microbiota of two batches of soybean sprouts was studied by culture-dependent and independent methods throughout storage at 10 °C. Viable cell counts of bacteriocin-treated samples revealed some modifications only for lactic acid bacteria and enterococci during storage. In the control samples from batch 1, the culture-independent DGGE analysis revealed species from genera Rahnella and Serratia as the predominant bacteria at early stages. Several bands corresponding to other genera (two Pantoea bands, one Escherichia band, and five Enterobacter bands) were also detected during storage of control samples, especially at days 3 and 5, while one Rahnella band disappeared. By contrast, some of the enterobacteria (Pantoea Escherichia and Enterobacter) were not detected or showed very faint bands in batch 1 bacteriocin-treated samples, in which two new and intense bands corresponding to genera Enterococcus and Leuconostoc were detected. Batch 2 showed a more homogeneous bacterial population, composed mainly by species of genus Enterobacter together with Pantoea. The major modifications detected in the bacteriocin-treated samples from batch 2 included the loss of one genus Enterobacter band at days 3, 5 and 7, and the detection of a new band corresponding to genus Leuconostoc at days 5 and 7. These results suggest that bacteriocin treatment disturbs the microbial balance in sprouts, producing changes in the microbial profile that cannot be detected by culture-dependent methods. The results also encourage the use of culture-independent methods to gain more insights into the global effects of bacteriocins in food systems.     

Physical and nutritional conditions for optimized production of bacteriocins by lactic acid bacteria – A review

ABSTRACT

There has been an increasing debate about the use of synthetic chemical compounds and the consequences of their use in food preservation. In this context, the utilization of some natural compounds produced by bacteria, showing an inhibitory effect against microorganisms associated with food contamination, have gained attention as preservation technology. In order to improve the production and yield costs of bacteriocins, detailed studies are necessary to determine the conditions that allow an optimized production and extraction of bacteriocins from lactic acid bacteria (LAB). In this context, this article aims to discuss the information regarding the main factors that influence bacteriocin production by LAB. The biosynthesis of bacteriocins can be influenced by various culture conditions, such as the composition of the medium, pH, temperature and growth kinetics of the microorganisms. One of the limiting factors for the use of bacteriocins on a large scale in food preservation is the economic factor. In order for the production costs of bacteriocins to be reduced, making them attractive, it is necessary to know the optimum parameters of production, thus maximizing productivity and making costs more attractive.     

Analysis of diglycolic acid in food packaging,over the counter products,direct additive carboxymethyl cellulose,and retail foods

ABSTRACT

Carboxymethyl cellulose (i.e. CMC or cellulose gum) is used as a direct additive for foods and drugs to change texture and act as a binder. CMC can also be a fluid absorbent used in food packaging and food contact materials. CMC and other carboxymethyl starches are synthesised by condensing glycolic acid with monochloroacetic acid. Diglycolic acid (DGA) is a byproduct produced by this condensation which cannot be completely removed. Currently, there are no analytical methods to accurately detect and quantify DGA in foods and food packaging materials. A method using a methanol/water extraction coupled with weak anion exchange solid phase extraction cleanup for more complex matrices was developed. A novel LC-MS/MS method was used to determine the DGA concentration in food contact materials, food grade direct additive CMC, and foods containing CMC. This paper will discuss the development of a new method for the preparation and cleanup of various food matrices and LC-MS/MS analysis for the presence of DGA.     

Combination of emerging technologies for the extraction of bioactive compounds

Abstract

With the growing consumer demands for greener alternatives that do not involve toxic chemicals as well as the industry concerns of sustainable, nontoxic routes of extraction, the applications of novel extraction technologies in the food industry have been widely studied. This review discussed the novel extraction technologies including their mechanisms, protocols, influencing factors, advantages and drawbacks, as well as a comprehensive summary of the combination of the novel extraction technologies for phyto-bioactive compounds. Novel extraction methods, including ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and enzyme-assisted extraction (EAE), are considered as clean, green and efficient alternative to conventional extraction technologies. Their combinations, ultrasound-assisted enzymatic extraction (UAEE), microwave-assisted enzymatic extraction (MAEE) and ultrasonic microwave-assisted extraction (UMAE), can exhibit higher potential extraction ability. However, some of them need specific equipment. The food industry in the extraction sector should choose a proper extraction method which has a balance between product quality, process efficiency, production costs and environmentally friendly processes. The current review presented comprehensive references for future research on the novel extraction of phyto-bioactive compounds extraction.

1. Highlights

2. Novel clean, green and efficient alternative to conventional extraction technologies are discussed.

3. Combination of the novel extraction technologies for synergistic effects.

4. Minimal degradation and enhanced extraction yields.

5. Extraction mechanisms, advantages and drawbacks associated with novel extraction technologies.

     

Nanomaterials for products and application in agriculture,feed and food

BackgroundNanotechnology applications can be found in agricultural production, animal feed, food processing, food additives and food contact materials (hereinafter referred to as agri/feed/food). A great diversity of nanomaterials is reported to be currently used in various applications, while new nanomaterials and applications are reported to be in development.Scope and approachIt is expected that applications of nanomaterials in agri/feed/food will increase in the future and thereby increase the human and environmental exposure to such materials. To gain up-to-date knowledge we explored and reviewed the already marketed and in-development applications of nanomaterials in the agri/feed/food sectors upon the request of the European Food Safety Authority (EFSA). In this paper the results of the project are highlighted and discussed in more detail.Key findings and conclusionsThe majority of the applications of nanomaterials that we identified concerned application in food as food additives and food contact materials, while much fewer applications seem to be developed for agriculture and feed. Nano-encapsulates, silver, titanium dioxide and silica are the most often mentioned nanomaterials in the literature. About half of the identified applications are claimed to be already in use. In-development applications are found for nano-encapsulates and nano-composites in novel foods, food and feed additives, biocides, pesticides and food contact materials.     

Recent developments in cold plasma decontamination technology in the food industry

BackgroundThe advent of the 21^st century has witnessed a growing demand of safe and nutritious foods. The food industry is adopting novel non-thermal food processing technologies. Cold plasma is one such promising non-thermal food processing method which uses charged, highly reactive gaseous molecules and species to inactivate contaminating microorganisms on foods and packaging materials.Scope and approachThe paper gives the reader an overview of the cold plasma technology in food industry. It reviews principles of plasma generation, including mechanisms of action of the process on microorganisms. It also highlights different plasma generation systems, various published results of plasma application to inactivate microorganisms in vitro and in various food products, food packages and equipment surfaces. The challenges of the process, its effects on food quality and the future prospects are highlighted.Key findings and conclusionsThis article aims to review and apprise readers about the important fundamentals and latest trends in the Cold Plasma technology. The on-going studies on plasma technology prove that cold plasma is strongly effective for surface decontamination, with efforts in-progress for liquid processing. The short time of application causes no significant deterioration in food products. Thus, it is an apt alternative processing technology which could also help to counter food allergenicity, seed germination, packaging material printing, waste-water treatment, modify food functionality, extract bio-actives etc. Further research is needed for scaling-up of this process for future commercialization.     

Data mining derived from food analyses using non-invasive/non-destructive analytical techniques; determination of food authenticity,quality & safety in tandem with computer science disciplines

BackgroundFood quality, safety and authenticity are important issues for consumers, governments, as well as the food industry. In the last decade, several researchers have attempted to go beyond traditional microbiological, DNA-based and other methods using rapid techniques. This broad term involves a variety of sensors such as hyperspectral and multispectral imaging, vibrational spectroscopy, as well as biomimetic receptors.Scope and approachThe resulting data acquired from the above-mentioned sensors require the application of various case-specific data analysis methods for the purpose of simple understanding and visualization of the acquired high-dimensional dataset, but also for classification and prediction purposes.Key findings and conclusionsIt is evident that rapid techniques coupled with data analysis methods have given promising results in several food products with various sensors. Additionally there are several applications, new sensors and new algorithms that remain to be explored and validated in the future.     

Three-phase partitioning as an elegant and versatile platform applied to nonchromatographic bioseparation processes

ABSTRACT

In recent years, a big trend has been the development of rapid, green, efficient, economical, and scalable approaches for the separation and purification of bioactive molecules from natural sources, which can be used in food, cosmetics, and medicine. As a new nonchromatographic bioseparation technology, three-phase partitioning (TPP) is attracting the attention of a growing number of scientists and engineers. Although a number of studies have been published in the last 40 years regarding the extraction, separation, and purification of numerous bioactive molecules using TPP systems, a background review on TPP partitioning fundamentals and its applications is much needed. Therefore, the present review focuses in detail on the TPP separation process, including the definition of TPP, partitioning mechanisms, parameters for establishing the suitable condition to form precipitate such as concentration of ammonium sulfate, content of tert-butanol, pH and temperature, and the application for separation and purification of protein, enzyme, plant oil, polysaccharide, and other small molecule organic compounds. In addition, the possible directions of future developments in TPP technology are discussed. The review presents a good opportunity, as well as a challenge for scientists, to understand the detailed partitioning rule and to take better use of TPP for the production and separation of various bioactive molecules, which have been intensively applied in the food and medical fields.     

Early-life food nutrition,microbiota maturation and immune development shape life-long health

ABSTRACT

The current knowledge about early-life nutrition and environmental factors that affect the interaction between the symbiotic microbiota and the host immune system has demonstrated novel regulatory target for treating allergic diseases, autoimmune disorders and metabolic syndrome. Various kinds of food nutrients (such as dietary fiber, starch, polyphenols and proteins) can provide energy resources for both intestinal microbiota and the host. The indigestible food components are fermented by the indigenous gut microbiota to produce diverse metabolites, including short-chain fatty acids, bile acids and trimethylamine-N-oxide, which can regulate the host metabolized physiology, immunity homeostasis and health state. Therefore it is commonly believed early-life perturbation of the microbial community structure and the dietary nutrition interference on the child mucosal immunity contribute to the whole life susceptibility to chronic diseases. In all, the combined interrelationship between food ingredients nutrition, intestinal microbiota configurations and host system immunity provides new therapeutic targets to treat various kinds of pathogenic inflammations and chronic diseases.     

Potential of bacteriocinogenic Lactococcus lactis subsp. lactis inhabiting low pH vegetables to produce nisin variants

Antimicrobial behavior of lactic acid bacteria (LAB) has been explored since many years to assess their ability to produce bacteriocin, a natural preservative, to increase the shelf life of food. This study aims to characterize bacteriocin producing strains of lactic acid bacteria isolated from acidic to slightly acidic raw vegetables including tomato, bell pepper and green chili and to investigate their potential to inhibit food related bacteria. Among twenty nine LAB screened for antimicrobial activity, three exhibited antagonism against closely related bacterial isolates which was influenced by varying temperature and pH. They were identified up to strain level as Lactococcus lactis subsp. lactis TI-4, L. lactis subsp. lactis CE-2 and L. lactis subsp. lactis PI-2 based on 16S rRNA gene sequence. Their spectrum of inhibition was observed against food associated strains of Bacillus subtilis and Staphylococcus aureus. Moreover, L. lactis subsp. lactis PI-2 selected on the basis of higher antimicrobial activity was further evaluated for bacteriocin production which was detected as nisin A and nisin Z. These findings suggest the possible use of L. lactis strains of vegetable origin as protective cultures in slightly acidic as well as slightly alkaline food by the bio-preservative action of bacteriocins.     

Short Communication: Culture-Independent Detection of Lactic Acid Bacteria Bacteriocin Genes in Two Traditional Slovenian Raw Milk Cheeses and Their Microbial Consortia

Two Slovenian traditional raw milk cheeses, Tolminc (from cows’ milk) and Kraški (from ewes’ milk), were examined for the presence of 19 lactic acid bacteria bacteriocin genes by PCR analysis of total DNA extracts from 9 cheeses and from consortia of strains isolated from these cheeses. Eleven bacteriocin genes were detected in at least one cheese or consortium, or from both. Different cheeses or consortia contained 3 to 9 bacteriocin determinants. Plantaricin A gene determinants were found in all cheese and consortia DNA extracts. Genes for enterocins A, B, P, L50A, and L50B, and the bacteriocin cytolysin were commonly detected, as were genes for nisin. These results indicate that bacteriocinogenic strains of Lactobacillus, Enterococcus, and Lactococcus genera with protective potential are common members of indigenous microbiota of raw milk cheeses, which can be a good source of new protective strains.     

A Comprehensive Overview on Microalgal-Fortified/Based Food and Beverages

ABSTRACT

Microalgae produce a variety of compounds that can be used for aquaculture, nutraceutical purposes, and third-generation biofuel sectors. Moreover, they have been considered for the production of fortified food and beverages claiming to be healthier than other foods. Using microalgal oil or incorporating microalgae biomass or their metabolites in food and beverages provides health benefits due to properties such as anti-inflammatory, antioxidant, immune-enhancing, and to their role against various diseases such as cardiovascular metabolic, atherosclerosis, and hypertension. This review focuses on the worldwide research carried out about the incorporation of microalgae – either biomass or their high-value compounds – in food and beverages, and on the microalgal fortified/based food and beverages currently present worldwide on the market. The metabolites bioavailability aspect and the current legislation are considered. There is an ever-growing interest in this field but the volume of production is still limited. Various challenges, one of which is the cost of producing biomass, need to be overcome for a profitable market. More effort, involving different expertise, is needed to improve the microalgal production system, from cultivation to harvesting and biorefinery, to produce improved novel products.     

Use of encapsulated natural compounds as antimicrobial additives in food packaging: A brief review

BackgroundSynthetic chemical preservatives in food can be harmful to human health. These problems have increasingly attracted concern and interest from researchers, which has led to the study and application of non-toxic essential oils with preservative ability in food products and food packaging. A great challenge in this sense is their facile degradation during processing of the food and manufacturing processes during food packing.Scope and approachEncapsulation is an interesting technique to improve the physical-chemical and microbiological stability of these essential oils, as well as to achieve controlled release. This review provides a detailed overview of encapsulation in the food industry, focusing on the application of procedures to encapsulate antimicrobial essential oils.Key findings and conclusionsThis review focuses on recent studies related to nanotechnology and the nano and microencapsulation of essential oils. This study provides valuable insight that may be useful for identifying trends in the commercialization of nanotechnological products or for identifying new research areas. The results published to date confirm that the encapsulation promotes the protection of active compounds, enabling industrial applications of active packaging.     

Applications of chia (Salvia hispanica L.) in food products

BackgroundThe outstanding nutritional and technological properties lead to innovative applications of chia (Salvia hispanica L.) in food products.Scope and approachThe aim of this contribution is to give an overview of the various food application approaches for chia. The nutritional and technological properties of chia as well as its technological and innovative utilization are presented. Examples for the various applications in food products are given in five main topics: baked goods, dairy products, meat and fish products, gluten-free products and other products such as functional food, hydrocolloid and thickener.Key findings and conclusionsBesides the nutritional benefits of chia incorporation in food products the technological effects are emphasized very often. Summarized in five main topics, most authors conclude that chia is a valuable food ingredient for functional food development. The application of chia in baked goods for example is beneficial not only to improve the nutritional value but acting as hydrocolloid or substitute egg, fat or gluten. The increase of oil stability and applications as food thickener in novel food applications are of high importance too. As different chia fractions give various options for applications the utilization of chia for further food products will increase significantly in the future.