In recent years, great interest has been focused on using natural antioxidants in food products, due to studies indicating possible adverse effects that may be related to the consumption of synthetic antioxidants. A variety of plant materials are known to be natural sources of antioxidants, such as herbs, spices, seeds, fruits and vegetables. The interest in these natural components is not only due to their biological value, but also to their economic impact, as most of them may be extracted from food by-products and under-exploited plant species. This article provides an overview of current knowledge on natural antioxidants: their sources, extraction methods and stabilization processes. In addition, recent studies on their applications in the food industry are also addressed; namely, as preservatives in different food products and in active films for packaging purposes and edible coatings.

https://www.mdpi.com/1420-3049/24/22/4132/pdf

Antioxidants of Natural Plant Origins: From Sources to Food Industry Applications.

The Olive tree (Olea europaea L), a native of the Mediterranean basin and parts of Asia, is now widely cultivated in many other parts of the world for production of olive oil and table olives Olive is a rich source of valuable nutrients and bioactives of medicinal and therapeutic interest Olive fruit contains appreciable concentration, 1–3% of fresh pulp weight, of hydrophilic (phenolic acids, phenolic alchohols, flavonoids and secoiridoids) and lipophilic (cresols) phenolic compounds that are known to possess multiple biological activities such as antioxidant, anticarcinogenic, antiinflammatory, antimicrobial, antihypertensive, antidyslipidemic, cardiotonic, laxative, and antiplatelet Other important compounds present in olive fruit are pectin, organic acids, and pigments Virgin olive oil (VOO), extracted mechanically from the fruit, is also very popular for its nutritive and health-promoting potential, especially against cardiovascular disorders due to the presence of high levels of monounsaturates and other valuable minor components such as phenolics, phytosterols, tocopherols, carotenoids, chlorophyll and squalene The cultivar, area of production, harvest time, and the processing techniques employed are some of the factors shown to influence the composition of olive fruit and olive oil This review focuses comprehensively on the nutrients and high-value bioactives profile as well as medicinal and functional aspects of different parts of olives and its byproducts Various factors affecting the composition of this food commodity of medicinal value are also discussed

https://www.mdpi.com/1422-0067/13/3/3291/pdf

Valuable Nutrients and Functional Bioactives in Different Parts of Olive (Olea europaea L.)—A Review

Yeast strains endowed with robustness towards copper and/or enriched in intracellular Cu might find application in biotechnology processes, among others in the production of functional foods. Moreover, they can contribute to the study of human diseases related to impairments of copper metabolism. In this study, we investigated the molecular and physiological factors that confer copper tolerance to strains of baker's yeasts. We characterized the effects elicited in natural strains of Candida humilis and Saccharomyces cerevisiae by the exposure to copper in the culture broth. We observed that, whereas the growth of Saccharomyces cells was inhibited already at low Cu concentration, C. humilis was naturally robust and tolerated up to 1 g · L-1 CuSO4 in the medium. This resistant strain accumulated over 7 mg of Cu per gram of biomass and escaped severe oxidative stress thanks to high constitutive levels of superoxide dismutase and catalase. Both yeasts were then "evolved" to obtain hyper-resistant cells able to proliferate in high copper medium. While in S. cerevisiae the evolution of robustness towards Cu was paralleled by the increase of antioxidative enzymes, these same activities decreased in evolved hyper-resistant Candida cells. We also characterized in some detail changes in the profile of copper binding proteins, that appeared to be modified by evolution but, again, in a different way in the two yeasts. Following evolution, both Candida and Saccharomyces cells were able to proliferate up to 2.5 g · L-1 CuSO4 and to accumulate high amounts of intracellular copper. The comparison of yeasts differing in their robustness, allowed highlighting physiological and molecular determinants of natural and acquired copper tolerance. We observed that different mechanisms contribute to confer metal tolerance: the control of copper uptake, changes in the levels of enzymes involved in oxidative stress response and changes in the copper-binding proteome. However, copper elicits different physiological and molecular reactions in yeasts with different backgrounds.

https://link.springer.com/content/pdf/10.1186%2F1475-2859-11-1.pdf

Laboratory evolution of copper tolerant yeast strains

In the last decade, the use of multivariate statistical techniques developed for analytical chemistry has been adopted widely in food science and technology. Usually, chemometrics is applied when there is a large and complex dataset, in terms of sample numbers, types, and responses. The results are used for authentication of geographical origin, farming systems, or even to trace adulteration of high value-added commodities. In this article, we provide an extensive practical and pragmatic overview on the use of the main chemometrics tools in food science studies, focusing on the effects of process variables on chemical composition and on the authentication of foods based on chemical markers. Pattern recognition methods, such as principal component analysis and cluster analysis, have been used to associate the level of bioactive components with in vitro functional properties, although supervised multivariate statistical methods have been used for authentication purposes. Overall, chemometrics is a useful aid when extensive, multiple, and complex real-life problems need to be addressed in a multifactorial and holistic context. Undoubtedly, chemometrics should be used by governmental bodies and industries that need to monitor the quality of foods, raw materials, and processes when high-dimensional data are available. We have focused on practical examples and listed the pros and cons of the most used chemometric tools to help the user choose the most appropriate statistical approach for analysis of complex and multivariate data.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1541-4337.12341

Trends in Chemometrics: Food Authentication, Microbiology, and Effects of Processing

How the sourdough may affect the functional features of leavened baked goods.

Pumpkin seed oils from naked and husk pumpkin seeds, produced by an industrial process and by laboratory extraction, were evaluated for fatty acid composition, tocopherol, sterol and squalene content. The major fatty acids in the oils from both varieties were oleic, linoleic and palmitic acid, followed by stearic acid. The ratios of monounsaturated to polyunsaturated fatty acids for husk and naked seed oils were about 0.60 and 0.75, respectively. Analysis of tocopherols in industrially pressed and laboratory-extracted oils showed that husk seed oils had higher amounts of total tocopherols than naked seed oils. Oils extracted in the laboratory had higher amounts of tocopherols than industrial oils. Pumpkin seed oil, in general, had a high level of squalene, which was higher in husk seed oils than in naked seed oils and in extracted than in pressed oils. The total amount of sterols was higher in husk than in naked seed oils and in extracted oil samples. The main sterols were A7-sterols and their content was similar in all samples, but the content of A5-sterols was higher in oil samples of husk pumpkin seed and in extracted than in pressed oils.

Chemical characteristics of oils from naked and husk seeds of Cucurbita pepo L.

https://bib.irb.hr/datoteka/330149.FOCH_7251.pdf

The antioxidant capacity and oxidative stability of virgin olive oil enriched with phospholipids

In the present study, the effects of three production processes (pressing of roasted pumpkin seed paste, pressing of unroasted ground pumpkin seeds and pressing of unroasted ground pumpkin seeds while cooling the press) on the properties of pumpkin seed oils produced from two seed varieties (husked and naked) were investigated. Oils produced with roasting had a higher initial peroxide value (PV), twofold higher total phenol content and better oxidative stability while cold pressed oils had higher tocopherol content. Fatty acid and triacylglycerol compositions were not significantly affected by the processing conditions. Oxidative stability of the oils positively correlated with oleic acid content and negatively correlated with linoleic and linolenic acid contents. The lack of correlation in oxidative stability with tocopherol and polyphenol contents suggests that improvement in oxidative stability of roasted oils could have been caused by antioxidative Maillard reaction products or inactivation of oil degrading enzymes. In addition, oils produced from husked seeds had significantly higher linoleic acid, triacylglycerols (TAG) containing mainly linoleic acid (LLL, OLL and PLL), tocopherol and phenol contents while oleic acid and TAG containing mainly oleic acid (LOO and OOO) contents and oxidative stability were lower. Principal component analysis (PCA) of the analytical data confirmed the observed differences between oils from two varieties and three production processes.

Chemical Composition and Oxidative Stability of Roasted and Cold Pressed Pumpkin Seed Oils

The influence of harvest time on the intensity of bitterness and the level of phenol compounds in olive oil from the region of west Istria obtained from two local (Bianchera and Busa) and one introduced, Italian variety (Leccino) was studied. Olive fruits were harvested at three different harvesting periods, during four successive crops seasons. Immediately after harvesting, the fruits were processed under the same conditions in a pilot plant. Basic quality parameters, the content of total polyphenols, o-diphenols and the intensity of bitterness were determined in oil samples. Samples of oil obtained from the Bianchera and Busa varieties were additionaly tested for stability at elevated temperature (98 °C) and under the influence of UV-light. The results elaborated statistically showed the level of phenol compounds and the intensity of bitterness to be significantly influenced by both the harvest time and olive variety, with the influence of harvest time being more pronounced. The applied tests for accelerated deterioration of oil indicated a more rapid increase in the peroxide value in oil samples of both varieties exposed to UV light than in those exposed to elevated temperature. Both tests showed better stability of the oil obtained from the Bianchera variety.

Dubravka Škevin

Papers

Chemical characteristics of oils from naked and husk seeds of Cucurbita pepo L.

The antioxidant capacity and oxidative stability of virgin olive oil enriched with phospholipids

Chemical Composition and Oxidative Stability of Roasted and Cold Pressed Pumpkin Seed Oils

The influence of variety and harvest time on the bitterness and phenolic compounds of olive oil

Ready-to-use green polyphenolic extracts from food by-products.