A review on influencing factors on the minimum inhibitory concentration of essential oils

With growing interest in essential oils as natural preservatives in the food industry, the literature is expanding enormously. To understand the antimicrobial activity of essential oils, the antimicrobial mechanism of individual essential oil (EO) compounds, and their minimum inhibitory concentrations (MICs), are interesting starting points for research. Therefore, and to get insight into the factors influencing their antimicrobial activities, the Web of Science was searched for MICs of EO compounds (1995–2016). Many MICs for individual EO compounds have already been reported in the literature, but there is large variability in these data, even for the MIC of the same compound against the same species.

No correlation was found between the tested structural parameters of EO compounds (polarity, water solubility, dissociation constant, molecular weight and molecular complexity) and their MICs against all microorganisms, Gram-negative bacteria, Gram-positive bacteria and fungi. Few clear differences in sensitivity between microorganisms could be found. Based on this review it is clear that different incubation conditions, culture media and the use of emulsifiers/solvents have an influence on the MIC, causing big variance. This review points out the need for a good international standard method to assess the antimicrobial activity of EO compounds for better comparability between studies.     

Innovative applications of food-related emulsions

Research on oxidative stability of multiple emulsions is very scarce. Given that this is a relevant topic that must be ascertained before the successful application of multiple emulsions in foods (especially when a combination of highly unsaturated oils is used as a lipid phase), this review mainly focuses on various aspects of the multiple emulsions.

Fat replacement in meat products using emulsions is critically discussed along with innovative applications of natural antioxidants in food-based emulsions and multiple emulsions based on bioactive compounds/encapsulation as well as confectionery products.     

Comparison of blood lipid-lowering effects of olive oil and other plant oils: A systematic review and meta‐analysis of 27 randomized placebo‐controlled clinical trials

Objective: We aim to report a systematic review and meta-analysis of randomized controlled trials (RCTs) on effects of olive oil consumption compared with other plant oils on blood lipids.

Methods: PubMed, web of science, Scopus, ProQuest, and Embase were systematically searched until September 2017, with no age, language and design restrictions. Weighed mean difference (WMD) and 95% confidence interval (CI) were expressed as effect size. Sensitivity analyses and pre specified subgroup was conducted to evaluate potential heterogeneity. Meta-regression analyses were performed to investigate association between blood lipid-lowering effects of olive oil and duration of treatment.

Results: Twenty-seven trials, comprising 1089 participants met the eligibility criteria. Results of this study showed that compared to other plant oils, high-density lipoprotein level increased significantly more for OO (1.37 mg/dl: 95% CI: 0.4, 2.36). Also OO consumption reduced total cholesterol (TC) (6.27 mg/dl, 95% CI: 2.8, 10.6), Low-density lipoprotein (LDL-c) (4.2 mg/dl, 95% CI: 1.4, 7.01), and triglyceride (TG) (4.31 mg/dl, 95% CI: 0.5, 8.12) significantly less than other plant oils. There were no significant effects on Apo lipoprotein A1 and Apo lipoprotein B.

Conclusion: This meta-analysis suggested that OO consumption decreased serum TC, LDL-c, and TG less but increased HDL-c more than other plant oils.     

Influence of type of natural emulsifier and microfluidization conditions on Capsicum oleoresin nanoemulsions properties and stability

There is a growing interest in the fabrication of colloidal delivery systems for bioactive compounds assembled from natural ingredients, particularly plant-based ones. In this study, Capsicum oleoresin was encapsulated within oil-in-water nanoemulsions by high-pressure microfluidization from natural emulsifiers: whey protein (WP), pea protein (PP), quillaja saponin (QS), and sunflower lecithin (SL). The influence of emulsifier, concentration, and microfluidization conditions (pressure and number of passes), on particle diameter and zeta-potential of nanoemulsions was evaluated. Particle diameter decreased with increasing homogenization pressure and number of passes. All emulsifiers were capable of forming charged droplets with dimensions in the nanometer range at sufficiently high concentrations. The stability of nanoemulsions to environmental stresses (pH, ionic strength, and heating) and storage was studied. The pH and salt stabilities were dependent on the emulsifier type. Overall, natural emulsifiers were effective in producing Capsicum oleoresin-loaded nanoemulsions with small particle size and capsaicin stability.     

Effect of different sources of dietary omega‐3 fatty acids on general performance and fatty acid profiles of thigh,breast, liver and portal blood of broilers

One hundred and sixty‐eight 1‐day‐old Cobb broiler chickens were randomly assigned to 12 broiler cages to determine the dietary effect of different sources of oils rich in long‐chain omega‐3 polyunsaturated fatty acids (LCω3PUFA). The following oils were added to the feed at a concentration of 12.5 g kg^?1: a highly refined seal blubber oil (SBO) containing 225 g kg^?1 LCω3PUFA; a fish oil (FO) concentrate containing >800 g kg^?1 LCω3PUFA in the form of triglycerides; and an FO concentrate containing >600 g kg^?1 LCω3PUFA in the form of ethyl esters. Fatty acid profiles of the breast and thigh meat were measured in order to determine the deposition of LCω3PUFA into the body tissues, whilst fatty acid profiles of the liver and the portal blood were taken in order to deduce consequences of the different ester forms on the absorption process. A triangular sensory evaluation was performed on the breast meat. The levels of LCω3PUFA in all tissues and the portal blood reflected the concentrations of LCω3PUFA in the diets. The sensory properties of the breast meat were negatively influenced by ethyl ester supplementation only. Copyright © 2004 Society of Chemical Industry     

Use of lactic acid bacteria and yeasts to reduce exposure to chemical food contaminants and toxicity

Chemical contaminants that are present in food pose a health problem and their levels are controlled by national and international food safety organizations. Despite increasing regulation, foods that exceed legal limits reach the market. In Europe, the number of notifications of chemical contamination due to pesticide residues, mycotoxins and metals is particularly high. Moreover, in many parts of the world, drinking water contains high levels of chemical contaminants owing to geogenic or anthropogenic causes.

Elimination of chemical contaminants from water and especially from food is quite complex. Drastic treatments are usually required, which can modify the food matrix or involve changes in the forms of cultivation and production of the food products. These modifications often make these treatments unfeasible. In recent years, efforts have been made to develop strategies based on the use of components of natural origin to reduce the quantity of contaminants in foods and drinking water, and to reduce the quantity that reaches the bloodstream after ingestion, and thus, their toxicity. This review provides a summary of the existing literature on strategies based on the use of lactic acid bacteria or yeasts belonging to the genus Saccharomyces that are employed in food industry or for dietary purposes.     

Fortification of Foods with Omega-3 Polyunsaturated Fatty Acids

A $600 million nutritional supplements market growing at 30% every year attests to consumer awareness of, and interests in, health benefits attributed to these supplements. For over 80 years the importance of polyunsaturated fatty acid (PUFA) consumption for human health has been established. The FDA recently approved the use of ω-3 PUFAs in supplements. Additionally, the market for ω-3 PUFA ingredients grew by 24.3% last year, which affirms their popularity and public awareness of their benefits. PUFAs are essential for normal human growth; however, only minor quantities of the beneficial ω-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are synthesized by human metabolism. Rather PUFAs are obtained via dietary or nutritional supplementation and modified into other beneficial metabolites. A vast literature base is available on the health benefits and biological roles of ω-3 PUFAs and their metabolism; however, information on their dietary sources and palatability of foods incorporated with ω-3 PUFAs is limited. DHA and EPA are added to many foods that are commercially available, such as infant and pet formulae, and they are also supplemented in animal feed to incorporate them in consumer dairy, meat, and poultry products. The chief sources of EPA and DHA are fish oils or purified preparations from microalgae, which when added to foods, impart a fishy flavor that is considered unacceptable. This fishy flavor is completely eliminated by extensively purifying preparations of n-3 PUFA sources. While n-3 PUFA lipid autoxidation is considered the main cause of fishy flavor, the individual oxidation products identified thus far, such as unsaturated carbonyls, do not appear to contribute to fishy flavor or odor. Alternatively, various compound classes such as free fatty acids and volatile sulfur compounds are known to impart fishy flavor to foods. Identification of the causative compounds to reduce and eventually eliminate fishy flavor is important for consumer acceptance of PUFA-fortified foods.

[Supplementary materials are available for this article. Go to the publisher's online edition of Critical Reviews in Food Science and Nutrition for the following free supplemental files: Additional text, tables, and figures.]     

How dietary intake has been assessed in African countries? A systematic review

Background: Dietary patterns are often considered as one of the main causes of non-communicable diseases worldwide. It is of utmost importance to study dietary habits in developing countries since this work is scarce.

Objective: To summarize the most recent research conducted in this field in African countries, namely the most used methodologies and tools.

Methods: A systematic review was conducted on MEDLINE®/PubMed, aiming to identify scientific publications focused on studies of dietary intake of different African populations, in a ten-year period. Papers not written in English/Portuguese/Spanish, studies developed among African people but not developed in African countries, studies aiming to assess a particular nutrient/specific food/food toxin and studies that assessed dietary intake among children were excluded.

Findings: Out of 99 included studies, the 24-hour recall and the food-frequency questionnaire were the most used dietary intake assessment tools, used to assess diet at an individual level. It was also observed that often country-unspecific food composition databases are used, and the methodologies employed are poorly validated and standardized.

Conclusions: There is an emergent need to improve the existing food databases by updating food data and to develop suitable country-specific databases for those that do not have their own food composition table.     

Triacylglycerols Determination by High-temperature Gas Chromatography in the Analysis of Vegetable Oils and Foods: A Review of the Past 10 Years

The analysis of triacylglycerols by high-temperature gas chromatography, along the last 10 years has been reviewed in this paper. The interest in this topic has grown along the last years due to the triacylglycerols are the main components of oils and fats and they are being used for the characterization and authentication of foods products.

The most commonly used procedures, including the official methodologies, applying high-temperature gas chromatographic techniques are shown. Their importance in the characterization of different kind of samples, vegetable oils, seeds, dairy products, etc., is considered.

This review is not intended to be a comprehensive dissertation on the field of triacylglycerols analysis since that would require sufficient space to occupy a book in its own right. Rather, it will outline selected considerations and developments, where the technique has been applied.     

Histamine food poisonings: A systematic review and meta-analysis

Objective: The aim of this study was to assess the mean of histamine concentration in food poisoning.

Design: Systematic review and meta-analysis of reports published between 1959 and 2013.

Study selection: Main criteria for inclusion of studies were: all report types that present outbreaks of “histamine poisoning' or “scombroid syndrome” from food, including histamine content and type of food. Health status of people involved must be nonpathological.

Results: Fifty-five (55) reports were included, these studies reported 103 incidents. All pooled analyses were based on random effect model; histamine mean concentration in poisoning samples was 1107.21 mg/kg with confidence interval for the meta-mean of 422.62–2900.78 mg/kg; heterogeneity index (I2) was 100% (P < 0.0001); prediction interval was 24.12–50822.78 mg/kg. Fish involved in histamine poisoning was mainly tuna or Istiophoridae species. No clues of association between concomitant conditions (female sex, alcohol consumption, previous medication, and consumption of histamine releasing food) and histamine poisoning, were highlighted.

Conclusions: This is the first systematic review and meta-analysis that analyzes all the available data on histamine poisoning outbreaks evaluating the histamine concentration in food involved. Histamine mean concentration in poisoning samples was fairly high. Our study suffers from some limitations, which are intrinsic of the studies included, for instance the lack of a complete anamnesis of each poisoning episode.

Protocol registration: Methods were specified in advance and have been published as a protocol in PROSPERO database (18/07/2012 -CRD42012002566).     

A novel nanoemulsification method of stirring at the Θ-point with the tocopherol-based block co-polymer nonionic emulsifier PPG-20 Tocophereth-50

Nanoemulsions have recently become increasingly important as potential vehicles for the controlled delivery of cosmetics and for the optimized dispersion of active ingredients in particular skin layers. The preparation of conventional nanoemulsions requires mainly high‐pressure homogenization, which is unproductive and requires high energy due to its lower efficiency, limiting their practical applications. In order to solve these problems novel nanoemulsions were studied using a model system of pseudo‐ternary water/emulsifier/paraffin oil. Nanoemulsions were prepared by stirring a mixture of the tocopherol‐containing block co‐polymer emulsifier PPG‐20 Tocophereth‐50, paraffin oil, and distilled water at the Θ‐point using weight fractions of the dispersed phase (φ) of 0.31 to 0.82 and an emulsifier content of 1.0 to 9 wt.%. The emulsifying property of PPG‐20 Tocophereth‐50 in nanoemulsions was compared with that of the conventional emulsifiers Tocophereth‐43, a mixture of polysorbate 60 and sesquioleate (3/1), and phospholipids. Also the emulsifying property of PPG‐20 Tocophereth‐50 in the more hydrophilic oils caprylic/capric triglyceride and octyldodecanol was compared with that in paraffin oil. The stability and morphology of the resulting nanoemulsions were studied by visual inspection, optical microscopy, particle size analysis, and cryo‐scanning electron microscopy. In the nanoemulsion systems containing caprylic/capric triglyceride and octyldodecanol, respectively, as an oil phase PPG‐20 Tocophereth‐50 showed emulsification properties similar to those in paraffin oil. The conventional emulsifiers Tocophereth‐43, a mixture of polysorbate 60 and sesquioleate (3/1), and phospholipids did not give nanoemulsions with high‐speed stirring. The block co‐polymer nonionic emulsifier PPG‐20 Tocophereth‐50 was found to produce stable nanoemulsions of mean droplet diameters ranging from 204 to 499 nm. The emulsification method of high‐speed stirring at the Θ‐point using PPG‐20 Tocophereth‐50 was found to be very effective for the preparation of stable nanoemulsions useful for applications in skincare cosmetics, cosmeceuticals, and drugs.     

Healthy Virgin Olive Oil: A Matter of Bitterness

Virgin olive oil (VOO) is the pillar fat of Mediterranean diet. It is made from olive fruits and obtained by squeezing olives without any solvent extraction. Respect to the seed oils, an unique polar polyphenol-rich fraction gives VOO a bitter and pungent taste.

The recent substantiation by European Food Safety Authority (EFSA) of a health claim for VOO polyphenols may represent an efficient stimulus to get the maximum health benefit from one of the most valuable traditional product of Mediterranean countries educating consumers to the relationship between the VOO bitterness and its health effect.

Agronomical practices and new processing technology to avoid phenolic oxidation and hydrolysis and to enhance the aromatic components of the VOO have been developed and they can be used to modulate taste and flavor to diversify the products on the market. VOOs having high concentration of phenol compounds are bitter and pungent therefore many people do not consume them, thus loosing the health benefits related to their intake.

In this paper, the chemist's and nutritionist's point of view has been considered to address possible strategies to overcome the existing gap between the quality perceived by consumer and that established by expert tasters. Educational campaigns emphasizing the bitter-health link for olive oils should be developed.     

Green Tea and Bone Marrow Transplantation: From Antioxidant Activity to Enzymatic and Multidrug-resistance Modulation

Epigallocatechin-3-gallate (EGCG), the main flavonoid of green tea (GT), could play an active role in the prevention of oxidative-stress-related diseases, such as hematologic malignancies. Some effects of EGCG are not imputable to antioxidant activity, but involve modulation of antioxidant enzymes and uric acid (UA) levels. The latter is the major factor responsible of the plasma non-enzymatic antioxidant capacity (NEAC). However, hyperuricemia is a frequent clinical feature caused by tumor lysis syndrome or cyclosporine side effects, both before and after bone marrow transplantation (BMT). Besides this, food–drug interactions could be associated with GT consumption and could have clinical implications.

The molecular mechanisms involved in the redox and drug metabolizing/transporting pathways were discussed, with particular reference to the potential role of GT and EGCG in BMT. Moreover, on reviewing data on NEAC, isoprostanes, uric acid, and various enzymes from human studies on GT, its extract, or EGCG, an increase in NEAC, without effect on isoprostanes, and contrasting results on UA and enzymes were observed.

Currently, few and contrasting available evidences suggest caution for GT consumption in BMT patients and more studies are needed to better understand the potential impact of EGCG on oxidative stress and metabolizing/transporting systems.     

Human microbiota in aging and infection: A review

In most developed countries, ageing of the population started more than a century ago and it seems to be emerged in a wide range of developing countries as well.

Moreover, research into ageing has moved forward in extremely rapidly rhythms nowadays, and the scientific area is of great interest, as implications for nearly all sectors of society, including work, social, economic features, in addition to nutrition and health issues which are involved.

The fragile elder population is affected and experienced more frequently infections than the younger population. Infections in elderly patients are of major medical importance because of hormonal changes, increased production of pro-inflammatory cytokines and chemokines, abnormalities of the telomeres which could cause a dysfunction of the immune system called immunosenescence and malnutrition.     

Beverage clouding agents: Review of principles and current manufacturing

Clouding agents are additives applied in fruit-flavored beverages to achieve a visual appearance similar to fresh juice. They consist of dispersions of small particles that impart turbidity. Use of emulsions is the most well established methodology utilized by the beverage industry, but citrus pulp, pigments, and biopolymer microgels are also employed in the manufacturing of clouding agents.

Long product shelf life is a prime requirement and hence instability is a perpetual concern. Often, clouding agents are produced concentrated, and thus they must be stable both as concentrates and in the final beverage. The composition and manufacturing processes can be adapted to modify the physicochemical characteristics of the clouding agent, and systems that are metastable, but still have sufficient stability can be achieved.

In this review article, the impact of, amongst other parameters, oil, weighting agent, emulsifier, stabilizer, as well as pressure, heat, pH and shear on turbidity and physical product stability will be discussed.     

A critical review on hepatoprotective effects of bioactive food components

Background: Bioactive food components are nonessential biomolecules, which help to give beneficial effects to human being against several diseases. Natural bioactive food components derived from plants and animals, such as phytosterols, carotenoids, polyphenols and fatty acids, have been proposed as valuable substitutions for anticipation and management of hepatotoxic effects and its chronic complications based on in vitro and in vivo studies.

Objectives of the study: To summarize drugs and chemical-induced hepatotoxicity and review how various bioactive food components attenuate the hepatotoxicity via cellular mechanisms.

Results: Remarkable studies demonstrated that the health promoting effects of bioactive components originated from plants have been frequently attributed to their antioxidant properties and facilitate to increase cellular antioxidant defense system and thereby scavenge free radicals, inhibit lipid peroxidation, augment anti-inflammatory potential, and further protect the liver from damage.

Conclusion: In this critical review, we summarize current progress in clarifying the molecular mechanism in hepatotoxicity and curative potential of the bioactive food components and its successive clinical outcomes in the field of drug discovery and overcome the problems of medication and chemical-induced hepatotoxic effects.     

Brassica Foods as a Dietary Source of Vitamin C: A Review

Brassica genus includes known horticultural vegetables with major economical importance worldwide, and involves vegetables of economical importance being part of the diet and source of oils for industry in many countries. Brassicales own a broad array of health-promoting compounds, emphasized as healthy rich sources of vitamin C. The adequate management of pre- and postharvest factors including crop varieties, growth conditions, harvesting, handling, storage, and final consumer operations would lead to increase or preserve of the vitamin C content or reduced losses by interfering in the catalysis mechanisms that remains largely unknown, and should be reviewed. Likewise, the importance of the food matrix on the absorption and metabolism of vitamin C is closely related to the range of the health benefits attributed to its intake. However, less beneficial effects were derived when purified compounds were administered in comparison to the ingestion of horticultural products such as Brassicas, which entail a closely relation between this food matrix and the bioavailability of its content in vitamin C. This fact should be here also discussed.

 These vegetables of immature flowers or leaves are used as food stuffs all over the world and represent a considerable part of both western and non-Western diets, being inexpensive crops widely spread and reachable to all social levels, constituting an important source of dietary vitamin C, which may work synergistically with the wealth of bioactive compounds present in these foods.     

Water activity,water glass dynamics,and the control of microbiological growth in foods

Water is probably the single most important factor governing microbial spoilage in foods, and the concept of water activity (a_w) has been very valuable because measured values generally correlate well with the potential for growth and metabolic activity. Despite some drawbacks (e.g., solute effect), the concept of a_w has assisted food scientists in their effort to predict the onset of food spoilage as well as to control food‐borne disease hazards in food products. In the last decade the concept of a_w has been challenged. It has been suggested that reduced‐moisture food products (e.g., low and intermediate) may be nonequilibrium systems and that most of them are in the amorphous metastable state, which is very sensitive to changes in moisture content and temperature. It has been proposed that the glass transition temperature T_g (temperature at which the glass‐rubber transition occurs), is a parameter that can determine many product properties, the safety of foods among them. The concept of water dynamics, originating in a food polymer science approach, has been suggested instead of a_w to better predict the microbial stability of intermediate‐moisture foods. The usage of a_w to predict microbial safety of foods has been discouraged on the basis that (1) in intermediate‐moisture foods the measured water vapor pressure is not an equilibrium one, and because a_w is a thermodynamic concept, it refers only to equilibrium; and (2) the microbial response may differ at a particular a_w when the latter is obtained with different solutes.

This review analyzes these suggestions on the basis of abundant experimental evidence found in the literature. It is concluded that nonequilibrium effects (e.g., inability of water to diffuse in a semimoist food) appear to be in many cases slow within the time frame (food's shelf life) of the experiments and/or so small that they do not affect seriously the application of the a_w concept as a predictor of microbial stability in foods.

The claims that a food science polymer approach to understanding the behavior of aqueous sugar glasses and concentrated solutions may be used to predict the microbial stability of food systems is not substantiated by experimental evidence. This approach does not offer, at the present time, a better alternative to the concept of a_w as a predictor of microbial growth in foods.

It is also recognized that a_w has several limitations and should be always used carefully, and this must include precautions regarding the possible influences of nonequilibrium situations. This aspect may be summarized by simply saying that anyone who is going to employ the term water activity must be aware of the implications of its definition.