Phospholipids in foods: prooxidants or antioxidants?

Lipid oxidation is one of the major causes of quality deterioration in natural and processed foods and thus a large economic concern in the food industry. Phospholipids, especially lecithins, are already widely used as natural emulsifiers and have been gaining increasing interest as natural antioxidants to control lipid oxidation. This review summarizes the fatty acid composition and content of phospholipids naturally occurring in several foods. The role of phospholipids as substrates for lipid oxidation is discussed, with a focus on meats and dairy products. Prooxidant and antioxidant mechanisms of phospholipids are also discussed to get a better understanding of the possible opportunities for using phospholipids as food antioxidants. © 2015 Society of Chemical Industry     

Viable but non-culturable forms of food and waterborne bacteria: Quo Vadis?

There is increasing evidence for a viable but non-culturable (VBNC) state in microbes, particularly in the stressing environment presented by modern foods with their varied pre-treatment and packaging strategies. This is a cause for concern because of evidence that microbial pathogens in such a state may retain their capacity to cause infections after ingestion by the consumer despite their inability to grow under the conditions employed in procedures for determining their presence in foods. Heavily stressed pathogenic species of bacteria in a VBNC or not immediately culturable state are potentially dangerous public health problems, particularly as stressed cells may be more virulent than well-fed bacteria. In this viewpoint article, I wish to focus on possible procedures for detecting such organisms and assessing their physiological state.     

Genome of non-living cells: trash or recycle?

Reproductive technologies have been often used as a tool in research not strictly connected with developmental biology. In this study, we retrace the experimental routes that have led to the adoption of two reproductive technologies, ICSI and somatic cell nuclear transfer (SCNT), as biological assays to probe the 'functionality' of the genome from dead cells. The structural peculiarities of the spermatozoa nucleus, namely its lower water content and its compact chromatin structure, have made it the preferred cell for these experiments. The studies, primarily focused on mice, have demonstrated an unexpected stability of the spermatozoa nuclei, which retained the capacity to form pronuclei once injected into the oocytes even after severe denaturing agents like acid treatment and high-temperature exposure. These findings inspired further research culminating in the production of mice after ICSI of lyophilized spermatozoa. The demonstrated non-equivalence between cell vitality and nuclear vitality in spermatozoa prompted analogous studies on somatic cells. Somatic cells were treated with the same physical stress applied to spermatozoa and were injected into enucleated sheep oocytes. Despite the presumptive fragile nuclear structure, nuclei from non-viable cells (heat treated) directed early and post-implantation embryonic development on nuclear transfer, resulting in normal offspring. Recently, lyophilized somatic cells used for nuclear transfer have developed into normal embryos. In summary, ICSI and SCNT have been useful tools to prove that alternative strategies for storing banks of non-viable cells are realistic. Finally, the potential application of freeze-dried spermatozoa and cells is also discussed.     

Addition of synthetic and natural antioxidants to α-tocopheryl acetate supplemented beef patties: effects of antioxidants and packaging on lipid oxidation

Friesian steers (n=5), aged 26–27 months, were fed a diet containing 2000 (supplemented) IU α-tocopheryl acetate/head/day for approximately 50 days prior to slaughter. Muscularis semimembranosus muscles from supplemented cattle were held in frozen storage (−20°C×12 weeks) following which they were minced and divided into five batches. The batches contained: (1) control, containing only vitamin E supplemented beef (C); (2) vitamin E supplemented beef with 4% soya oil (S); (3) vitamin E supplemented beef mixed with 0.2% Duralox NMC dissolved in 4% soya oil (R1); (4) vitamin E supplemented beef mixed with 0.25% Herbalox type 25 (containing 25 natural antioxidant extracts of rosemary) dissolved in 4% soya oil (R2); and (5) vitamin E supplemented beef mixed with a 1:1 mixture of 0.01% (w/w) BHA and 0.01% (w/w) BHT dissolved in 4% soya oil (B). The meat was then aerobically packaged (A) or packaged under the following modified atmospheres (MAP); 30:70 (M₁); 70:30 (M₂) or 80:20 (M₃) (O₂:CO₂). Oxidative stability (TBARS) and Hunter ‘a’ values (redness) were determined in all beef patties over 8 days of refrigerated (4°C) storage. Under MAP or aerobic packaging conditions, elevated oxygen levels brought about increased (P<0.05) TBARS numbers during refrigerated storage. However, the addition of rosemary extracts or BHA/BHT significantly (P<0.05) improved the oxidative stability of dietary α-tocopheryl acetate supplemented beef. Rosemary extracts were as effective in reducing TBARS as the combination of synthetic antioxidants, BHA/BHT.     

Inhibition of β-carotene degradation in oil-in-water nanoemulsions: Influence of oil-soluble and water-soluble antioxidants

The utilisation of carotenoids as functional ingredients (pigments and nutraceuticals) in many food and beverage products is currently limited because of their poor water-solubility, high melting point, chemical instability, and low bioavailability. This study examined the impact of antioxidants on the chemical degradation of β-carotene encapsulated within nanoemulsions suitable for oral ingestion. β-Carotene was incorporated into oil-in-water nanoemulsions stabilized by either a globular protein (β-lactoglobulin) or a non-ionic surfactant (Tween 20). Nanoemulsions were then stored at neutral pH and their physical and chemical stability were monitored under accelerated stress storage conditions (55 °C). β-Carotene degradation was monitored non-destructively using colour reflectance measurements. The rate of β-carotene degradation decreased upon addition of water-soluble (EDTA and ascorbic acid) or oil-soluble (vitamin E acetate or Coenzyme Q10) antioxidants. EDTA was more effective than ascorbic acid, and Coenzyme Q10 was more effective than vitamin E acetate. The utilisation of water-soluble and oil-soluble antioxidants in combination (EDTA and vitamin E acetate) was less effective than using them individually. Emulsions stabilized by β-lactoglobulin were more stable to colour fading than those stabilized by Tween 20. These results provide useful information for designing effective nanoemulsion-based delivery systems that retard the chemical degradation of encapsulated carotenoids during long term storage.     

Effects of feeding in free-range conditions or in confinement with different dietary MUFA/PUFA ratios and α-tocopheryl acetate, on antioxidants accumulation and oxidative stability in Iberian pigs

The experiment was undertaken to provide information of the influence of feeding either free-range or in confinement with different dietary MUFA/PUFA ratios and α-tocopheryl acetate supplementation (40 vs. 200 mg/kg) on tocopherol content and susceptibility to lipid oxidation of muscle and microsomes in Iberian pigs. The grass provided to the pigs had a similar α-tocopherol concentration to that observed for diets supplemented with 200 mg/kg α-tocopheryl acetate, and acorns supplied fourfold higher content of γ-tocopherol than the experimental diets. The α- and γ-tocopherol contents of muscle reflected the tocopherol concentration of the diets. Mono and Medium diets produced a similar MUFA/PUFA ratio in neutral and polar lipids of pig muscle to those fed outdoors. The lowest TBARS numbers were found in muscle samples from pigs fed a MUFA-enriched diet in confinement. No significant influence of free-range feeding or dietary fat on drip loss was found. However, α-tocopheryl acetate supplementation reduced (P<0.05) drip loss. Dietary vitamin E supplementation decreased the membrane lipid oxidation by 18% after 120 min. However, free-range feeding decreased the extent of microsome oxidation by 20%, 56% and 82% after 120 min when compared with those groups fed in confinement with high, medium and low MUFA/PUFA ratios, respectively. The hexanal concentration of muscle showed a similar trend to that observed for microsome induced-oxidation, suggesting, that hexanal determination is a more accurate method to measure lipid oxidation in iberian pig muscle than the thiobarbituric acid test.     

Cardiovascular disease and nutrient antioxidants: Role of low‐density lipoprotein oxidation

Increasing evidence indicates that oxidative modification of low‐density lipoprotein (LDL) is causally related to atherosclerosis. Oxidatively modified LDL (oxLDL), in contrast to native LDL, is taken up avidly by macrophages, leading to formation of lipid‐laden foam cells. Foam cells are pathognomonic of the atherosclerotic fatty streak. Modified LDL may also promote atherosclerosis by many other mechanisms, such as recruitment and retention of monocyte‐macrophages, T‐lymphocytes, and smooth muscle cells in the arterial intima, and cytotoxicity toward endothelial cells and macrophage‐derived foam cells. The “oxidation hypothesis of atherosclerosis” is supported by a number of in vivo findings, such as the presence of oxLDL in atherosclerotic lesions, and increased titers of autoantibodies against modified LDL in patients with atherosclerosis.

As a corollary of the oxidation hypothesis of atherosclerosis, antioxidants that can inhibit LDL oxidation may act as antiatherogens. This conception is supported by animal studies showing that antioxidants such as probucol, butylated hydroxytoluene, and α‐tocopherol can slow the progression of atherosclerosis. Epidemiological and clinical data indicate a protective role of dietary antioxidants against cardiovascular disease, including vitamin E, β‐carotene, and vitamin C. Likewise, basic research studies on LDL oxidation have demonstrated a protective role for antioxidants, present either in the aqueous environment of LDL or associated with the lipoprotein itself. More studies are needed to establish the effectiveness and determine the required doses of specific antioxidants to prevent and possibly treat cardiovascular disease.     

Lack of male teachers: a problem for students or teachers?

This article explores young people's perspectives on males and females as teachers, contrasting these with teachers' perceptions. It builds on 90 interviews of school students aged 13-14 and 60 follow-up interviews 4 years later. The first interviews were conducted in ethnographic context in two secondary schools in the mid-1990s in Helsinki, Finland. Whilst lack of male teachers is a recurrent theme in educational discussion, widely agreed among teachers, gender did not appear to be relevant when young persons talked about teachers. They appreciate teachers, irrespective of gender, who can teach and are friendly and relaxed, but who nevertheless keep order and make sure that students work. Male teachers who teach popular, non-academic subjects were often favoured by boys, but so were female teachers of academic subjects and increasingly as time went on. The interviews suggest that students do not need male teachers to act as 'male models'. They also suggest that male teachers should be sensitive in relationships with female students. When questioned explicitly, most of the interviewees did not regard lack of male teachers as a major problem     

Unexploited Acacia cyanophylla seeds: potential food sources of ω6 fatty acids and antioxidants?

BACKGROUND: In order to investigate new sources of dietary phytochemicals, recent studies have focused on underexploited seeds. In this study the total lipid contents, fatty acid profiles and levels of soluble proteins, minerals and antioxidants in seeds from 12 Acacia cyanophylla ecotypes commonly grown in Tunisia were determined. RESULTS: Total lipids averaged 101.7 g kg^?1 on a dry weight basis. Linoleic (61.11–65.45% of total fatty acid content), oleic (19.67–22.85%) and palmitic (9.18–9.98%) acids were the principal fatty acids. Smaller proportions of stearic (1.49–1.82%), vaccenic (1.13–2.05%) and palmitoleic (0.34–0.58%) acids were also quantified. Proteins (by Kjeldahl assay) averaged 107.2 g kg^?1 on a dry weight basis. Total phenolics averaged 1.91 g gallic acid equivalent kg^?1 dry weight (DW) and total flavonoids averaged 0.40 g rutin equivalent kg^?1 DW. The free radical‐scavenging activity determined by 2,2‐diphenyl‐1‐picrylhydrazyl assay averaged 0.59 mmol L^?1 Trolox equivalent antioxidant capacity (TEAC), while that determined by 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) assay averaged 0.28 mmol L^?1 TEAC. CONCLUSION: The findings of this study confirm the presence of ω6 fatty acids at high levels in A. cyanophylla seeds. These metabolites could be used as such and/or extracted for the formulation of supplements and/or ingredients to provide a ratio close to the ideal for the ω3/ω6 balance. Copyright © 2012 Society of Chemical Industry     

Corcyra cephalonica: A serious pest of stored products or a factitious host of biocontrol agents?

The rice moth, Corcyra cephalonica, is an economically significant stored product pest (SPP). It is widely distributed and causes severe damage to grains and products in storage under varying environmental conditions. However, compared to other Lepidopterous pests like Ephestia kuehniella and Plodia interpunctella, the pest potential of C. cephalonica is often underestimated. While farmers typically rely on chemical control to manage insect pests, recent studies suggest that non-chemical control methods can be used successfully as alternatives for their management. Therefore, in-depth knowledge of rice moth biology and its current pest status is essential for developing integrated management systems. Besides being a pest under natural conditions, Corcyra cephalonica also serves as a factitious host of natural enemies. It has a short life cycle and can be easily mass-reared on a variety of feeding media, making it a preferable alternative host with year-round availability, which can help in the cost-effective production of beneficial insects such as biocontrol agents and, as a result, in better management of other harmful agricultural insect pests. In the second part of this review, we examine the suitability of the rice moth as a laboratory host and conclude by determining whether Corcyra is best addressed as a serious pest of stored products or as a factitious host of biocontrol agents.