Effect of storage on refined and husk olive oils composition: Stabilization by addition of natural antioxidants from Chemlali olive leaves

Innovative Process for the Recovery of Oleuropein-Rich Extract from Olive Leaves and Its Biological Activities: Encapsulation for Activity Preservation with Concentration Assessment Pre and Post Encapsulation

Olive leaves, often regarded as agricultural and industrial waste, hold significant potential for economic and medicinal applications. This study examines the valorization of olive leaves through the extraction of phenolic compounds, notably oleuropein and hydroxytyrosol, using autoclave extraction techniques. It also investigates encapsulation techniques employing maltodextrin and sodium caseinate as wall materials to preserve the stability and bioavailability of these compounds. The results indicate a rich phenolic profile in the nonencapsulated olive leaf extract (OLE), demonstrating high antioxidant and antibacterial activities against various pathogens. The encapsulation process achieved high efficiency with a mixture of maltodextrin and sodium caseinate. Furthermore, FTIR spectroscopy and NMR analyses confirmed the presence of functional groups in the encapsulated extract, providing insight into its molecular structure. Overall, this study underscores the potential of olive leaves as a valuable source of bioactive compounds and highlights the importance of innovative extraction and encapsulation techniques to optimize their use across different applications.

Optimization of ultrasound-assisted extraction of phenols from Crocus sativus by-products using sunflower oil as a sustainable solvent alternative

In the last decade, there's been a rising emphasis on eco-friendly solvents in industry and academia due to environmental concerns. Vegetable oils are now recognized as a practical, non-toxic option for extracting phytochemicals from herbs. This study presents a novel, green, and user-friendly method for extracting phenolic content from Crocus sativus L. waste using ultrasound. It replaces conventional organic solvents with sustainable sunflower oil, making the process eco-friendly and cost-effective. The effects of temperature (18-52 °C), ultrasonic time (5-55 min), and solid-solvent ratio (5-31 g/100 mL) were assessed by applying response surface methodology (RSM) and Central composite design. The combined impact of solid-solvent ratio, temperature, and ultrasonic time led to heightened phenolic content and antioxidant activity in the enriched oil. However, when these variables were at their maximum levels, there was a decline in these attributes. The specific conditions found to be ideal were a solid-to-liquid ratio of 26 g/100 mL, a temperature of 45 °C, and a duration of 45 min. The optimum extraction condition yielded the expected highest phenolic content (317.15 mg/ Kg), and antioxidant activity (89.34%). The enriched oil with flower saffron enabled the utilization of renewable natural ingredients, ensuring the production of a healthy extract or product. Also, enriched oils find diverse applications in areas such as food, aquaculture, and cosmetics.

Absolute kinetics of peroxidation and antioxidant protection of intact triglyceride vegetable oils

To verfy their difference from isolated fatty acids, the absolute kinetics of peroxidation was studied for seven triglyceride-based oils of olive (OLI-1, OLI-2), high-oleic sunflower (SUN-HO), high-oleic and high-linoleic safflower (SAF-HO, SAF-HL) grapeseed (GRA) and borage (BOR), by oxygen uptake monitoring, using 2,6-di-tert-butyl-4-methoxyphenol and 2,2,5,7,8-pentamethyl-6-chromanol as reference inhibitors. Propagation constants (kp/M-1 s-1 at 303 K in PhCl) were respectively 34.8 ± 2.3, 35.1 ± 1.8, 40.6 ± 5.5, 36.0 ± 7.7, 160.8 ± 5.1, 145.1 ± 24.5, 275.1 ± 63.8, while oxidizability responded to empirical equation kp(2kt)-½/M-½s-½ = 1.63 × 10-3[allyl >CH2/M] + 1.82 × 10-2[bisallyl >CH2/M], based on fatty acids residues assessed by GC-MS. Peroxidation kinetics was markedly different from that of isolated fatty acids. The H-bond basicity of all oils was measured by FT-IR affording Abraham's βH2 values in the range 0.55 ± 0.03. H-bonding explained the protection of oils measured for seven reference phenolic antioxidants, except for the catechols quercetin and caffeic acid phenethyl ester, which were 2-to-4-folds more effective than expected, supporting a proposed different mechanism.

Effects of Soaking and Germination Treatments on the Nutritional, Anti-Nutritional, and Bioactive Characteristics of Adzuki Beans (Vigna angularis L.) and Lima Beans (Phaseolus lunatus L.)

Lima beans (Phaseolus lunatus) and adzuki beans (Vigna angularis) are some of the most nutritious underutilized pulses that are significant in being used as basic ingredients for the preparation of various food products. The present study aimed to determine the impact of soaking and germination on nutritional and bioactive components, in vitro protein digestibility, reducing power, metal chelating capacity, antioxidant activity, and anti-nutritional components of lima and adzuki beans. The findings showed that during the germination treatment, the in vitro protein digestibility of lima and adzuki beans increased by 14.75 and 10.98%, respectively. There was an increase in the antioxidant activity of lima beans by 33.48% and adzuki beans by 71.14% after 72 h of germination, respectively. The reducing power assay of lima and adzuki beans indicated an increase of 49.52 and 36.42%, respectively, during germination. Similarly, the flavonoid and metal chelating activity increased in lima and adzuki beans after 72 h of germination. In contrast, the anti-nutrients, such as phytic acid, tannin content, and trypsin inhibitor activity, decreased significantly p < 0.05 after 72 h of germination. These results are encouraging and allow for utilizing the flour obtained from the germinated beans in functional bakery products, which can contribute to eradicating protein deficiency among some population groups. At the same time, promoting soaking and germination of the beans as a way to enhance the nutritional quality and reduce anti-nutrients can contribute to the interest in these underutilized pulses. They could be seen as an additional tool to improve food security.

Metabolic Responses in Leaves of 15 Italian Olive Cultivars in Correspondence to Variable Climatic Elements

This study aims to evaluate the metabolic changes that occurred in olive leaves as responses over time to variations in climatic elements. Rainfall, temperature, and solar radiation data were collected over 4 months (August-November) to assess the impact of different climatic trends on the metabolism of the leaves of 15 Italian olive cultivars, cultivated at the experimental farm of the University of Florence. The net photosynthetic rate (AN) and stomatal conductance (gs), measured as main indicators of primary metabolism, were mainly influenced by the "cultivar" effect compared to the "climate" effect. The lowest AN value was showed by "Bianchera", while "Ascolana" recorded the highest (8.6 and 13.6 µmol CO2 m-2s-1, respectively). On the other hand, the secondary metabolism indicators, volatile organic compound (VOC) and oleuropein (OL) content, were much more influenced by climate trends, especially rainfall. A phase of high rainfall caused a significant increase in the VOCs emission from leaves, even with different behaviors among the genotypes. The highest differences were observed between "Maiatica di Ferrandina", with the highest average values (~85,000 npcs), and "Frantoio", which showed the lowest (~22,700 npcs). The OL content underwent considerable fluctuations in relation to the rainfall but also appeared to be controlled by the genotype. "Coratina" always showed the highest OL concentration (reaching the maximum ~98 mg g-1), indicating the great potential of this cultivar for the industrial recovery of OL.

Comparative Study on Chemical Composition of Green and Black Table Olives Brines of the Endemic ''Sigoise'' Cultivar: Recovery of high-Added Values Compounds

The effluents derived from the processing of table olives stand for a serious environmental problem. The study aims to valorize the brine water of table olives at different stages of ripening (green and black) of the Algerian variety Sigoise of Bejaia (East) and Mascara (West). The physico-chemical characterization revealed that these samples display have a high acid pH and salinity. The comparative study of phenolic levels exhibited showed very significant differences between the brine waters of green olives from Bejaia and Mascara, while the brines of black olives presented showed comparable levels. A high strong antioxidant potential was confirmed by DPPH (CI₅₀ =0.35 μg/100 ml-0.50 μg/100 ml) and FRAP (CI₅₀ =626.89 μg/100 ml-875.54 μg/100 ml) tests. Chemical screening by HPLC-DAD of the four samples identified high concentrations of hydroxytyrosol (HT) (390.4 mg/100 ml-360.8 mg/100 ml) and tyrosol (202.2 mg/100 ml-101.4 mg/100 ml). This study provided a deeper insight into the phenolic profile and the antioxidant potential of these brines.

Application of botanical products as nutraceutical feed additives for improving poultry health and production

Poultry is one of the most consumed sources of animal protein around the world. To meet the global demands for poultry meat and eggs, it is necessary to improve their nutrition to sustain the poultry industry. However, the poultry industry faces several challenges, including feedstuff availability, the banning of antibiotics as growth promoters, and several environmental stressors. Therefore, there is a critical need to include available nutraceuticals in the diet to sustain the poultry industry. Nutraceuticals are natural chemical substances that positively influence animal physiological and productive traits. Botanical products (such as fenugreek seeds, ginger roots, and olive leaves) are among the most commonly used nutraceuticals and are gradually gaining popularity in the poultry industry due to their immense benefits in nutrition and therapeutic properties. They can be added to the diet separately or in combination (as a natural antioxidant and immunostimulant) to improve poultry health and production. Botanical products are rich in essential oils and essential fatty acids, which have multiple benefits on the animal's digestive system, such as activating the digestive enzymes and restoring microbiota balance, enhancing poultry health, and production. These nutraceuticals have been shown to stimulate the expression of several genes related to growth, metabolism, and immunity. In addition, the essential oil supplementation in poultry diets up-regulated the expression of some crucial genes associated with nutrient transportation (such as glucose transporter-2 and sodium-glucose cotransporter-1). Previous studies have suggested that supplementation of botanical compounds increased broiler body weight and hen egg production by approximately 7% and 15%, respectively. Furthermore, the supplementation of botanical compounds enhanced the reproductive efficiency of hens and the semen quality of roosters by 13%. This review article discusses the significant effects of some botanical products in the poultry industry and how they can benefit poultry, especially in light of the ban on antibiotics as growth promoters.

An Overview on the Use of Extracts from Medicinal and Aromatic Plants to Improve Nutritional Value and Oxidative Stability of Vegetable Oils

Oil oxidation is the main factor limiting vegetable oils' quality during storage, as it leads to the deterioration of oil's nutritional quality and gives rise to disagreeable flavors. These changes make fat-containing foods less acceptable to consumers. To deal with this problem and to meet consumer demand for natural foods, vegetable oil fabricators and the food industry are looking for alternatives to synthetic antioxidants to protect oils from oxidation. In this context, natural antioxidant compounds extracted from different parts (leaves, roots, flowers, and seeds) of medicinal and aromatic plants (MAPs) could be used as a promising and sustainable solution to protect consumers' health. The objective of this review was to compile published literature regarding the extraction of bioactive compounds from MAPs as well as different methods of vegetable oils enrichment. In fact, this review uses a multidisciplinary approach and offers an updated overview of the technological, sustainability, chemical and safety aspects related to the protection of oils.

Effect of soaking and germination treatments on nutritional, anti-nutritional, and bioactive properties of amaranth (Amaranthus hypochondriacus L.), quinoa (Chenopodium quinoa L.), and buckwheat (Fagopyrum esculentum L.)

Pseudocereals have attracted the attention of nutritionists and food technologists due to their high nutritional value. In addition to their richness in nutritional and bioactive components, these are deficient in gluten and can serve as valuable food for persons suffering from gluten allergies. Processing treatments are considered an effective way to enhance the quality of food grains. Soaking and germination are traditional and most effective treatments for enhancing the nutritional and bioactive potential as well as reducing the anti-nutritional components in food grains. This study reflects the effect of soaking and germination treatments on nutritional, bioactive, and anti-nutritional characteristics of pseudocereals. There was a significant (p ≤ 0.05) increase in nutritional and bioactive components such as crude fiber, crude protein, phenolic components, antioxidant activity, and mineral content but reduced the anti-nutrients such as tannin and phytic acid. In amaranth, there was a significant increase (p ≤ 0.05) of 7.01, 74.67, 126.62, and 87.47% in crude protein, crude fiber, phenolic content, and antioxidant activity but significant (p ≤ 0.05) reduction of 32.30% and 29.57% in tannin and phytic acid contents, respectively. Similar changes in values of crude proteins, crude fiber, phenolic content, and antioxidant activity were observed in buckwheat and quinoa. While the anti-nutritional components such as tannin and phytic acid decreased by 59.91 and 17.42%, in buckwheat and 27.08% and 47.57%, in quinoa, respectively. Therefore, soaking and germination proved to be excellent techniques to minimize the anti-nutritional component and enhance the nutritional, bioactive, and antioxidant potential of these underutilized grains.

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Pseudocereals were found to be a rich source of nutritional and bioactive components.

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Processing treatments (soaking and germination) were found effective in improving the nutritional as well as bioactive components.

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The anti-nutrients such as tannin and phytic acid contents decreased significantly thereby enhancing the nutritional potential of these underutilized grains.

Syringa microphylla Diels: A comprehensive review of its phytochemical, pharmacological, pharmacokinetic, and toxicological characteristics and an investigation into its potential health benefits

BACKGROUND

Syringa microphylla Diels is a plant in the family Syringa Linn. For hundreds of years, its flowers and leaves have been used as a folk medicine for the treatment of cough, inflammation, colds, sore throat, acute hepatitis, chronic hepatitis, early liver cirrhosis, fatty liver, and oesophageal cancer.

PURPOSE

For the first time, we have comprehensively reviewed information on Syringa microphylla Diels that is not included in the Pharmacopoeia, clarified the pharmacological mechanisms of Syringa microphylla Diels and its active ingredients from a molecular biology perspective, compiled in vivo and in vitro animal experimental data and clinical data, and summarized the toxicology and pharmacokinetics of Syringa microphylla Diels. The progress in toxicology research is expected to provide a theoretical basis for the development of new drugs from Syringa microphylla Diels, a natural source of compounds that are potentially beneficial to human health.

METHODS

The PubMed, Google Scholar, China National Knowledge Infrastructure, Web of Science, SciFinder Scholar and Thomson Reuters databases were utilized to conduct a comprehensive search of published literature as of July 2021 to find original literature related to Syringa microphylla Diels and its active ingredients.

RESULTS

To date, 72 compounds have been isolated and identified from Syringa microphylla Diels, and oleuropein, verbascoside, isoacteoside, echinacoside, forsythoside B, and eleutheroside B are the main active components. These compounds have antioxidant, antibacterial, anti-inflammatory, and neuroprotective effects, and their safety and effectiveness have been demonstrated in long-term traditional applications. Molecular pharmacology experiments have indicated that the active ingredients of Syringa microphylla Diels exert their pharmacological effects in various ways, primarily by reducing oxidative stress damage via Nrf2/ARE pathway regulation, regulating inflammatory factors and inducing apoptosis through the MAPK and NF-κB pathways.

CONCLUSION

This comprehensive review of Syringa microphylla Diels provides new insights into the correlations among molecular mechanisms, the importance of toxicology and pharmacokinetics, and potential ways to address the limitations of current research. As Syringa microphylla Diels is a natural low-toxicity botanical medicine, it is worthy of development and utilization and is an excellent choice for treating various diseases.

Quality assessment of leaf extracts of 12 olive cultivars and impact of seasonal variation based on UV spectroscopy and phytochemcial content using multivariate analyses

INTRODUCTION

Recently, focus has been made on the health-oriented uses of olive leaves, a byproduct of olive production, as a potential source of antioxidants. Oleuropein is one of the phenolic components in olive leaves known for its high antioxidant value.

OBJECTIVE

The main aim of the current study was constructing a model for the quality assessment of olive leaves and their potential phytochemical content and hence biological value as well. The phytochemical variation in olive leaves in both flowering (spring) and fruiting seasons (autumn) was also investigated.

METHODS

In this study, the leaves of 12 different olive cultivars from different geographical origins growing in Egypt were assessed for their oleuropein content, total flavonoid (TF) content and total polyphenol (Pph) content in spring and autumn via ultraviolet (UV) spectroscopy and high-performance liquid chromatography (HPLC) coupled to multivariate data analyses. The antioxidant activity of olive leaf extracts was assessed using 2,2'-diphenyl-1-picrylhydrazyl (DPPH) assay.

RESULTS

Higher levels of oleuropein, TF and Pph content were found in spring with the highest oleuropein content in the Spanish cultivar; Manzanillo, followed by the Italian cultivar Coratina and the Egyptian Agizi Okasi (218.94, 151.58 and 122.18 mg/100 g of dried leaf extract, respectively). UV spectra was also measured and the collected data were coupled to multivariate analyses showing clustering of cultivars with common geographical origin.

CONCLUSION

Our findings emphasised the influence of collection time and type of cultivar on the chemical profile of olive leaves. The model presented herein, serves for the quality assessment of olive leaves based on their phytochemical profile.

Comparison of Phenolic Compounds in Olive Leaves by Different Drying and Storage Methods

Oleuropein, a bitter substance that exists in olive leaves, can be hydrolyzed to hydroxytyrosol. These are the main phenolic compounds, and they have beneficial properties to human bodies. In this study, we established a simple and new method to determine oleuropein and hydroxytyrosol quickly by HPLC. HPLC conditions were set as follows: water (A) acetonitrile (B) as mobile phase, gradient elution orders: 90%A–10%B for 0–10 min, 80%A–20%B for 14–30 min, and then change to 90%A–10%B for 30–33 min; detection wavelength: 280 nm. Compared with other detection methods, the method simplified the elution procedure and shortened the time. Additionally, we provided a better drying method and preservation of olive leaves in tea drinking production that were air-dried at room temperature of 25 °C.

Effects of Olive (Olea europaea L.) Leaves with Antioxidant and Antimicrobial Activities on In Vitro Ruminal Fermentation and Methane Emission

We evaluated whether olive leaves (OLs) are effective as feed additives and supplements for ruminants and the potential methane reduction effects during in vitro fermentation. Two Hanwoo cows (460 ± 20 kg) equipped with cannula were fed Timothy hay and corn-based feed 3% of the body weight at a ratio of 6:4 (8:30 a.m. and 5:00 p.m.). Ruminal fluid from the cows was collected and mixed before morning feeding. In vitro batch fermentation was monitored after 12 and 24 h of incubation at 39 °C, and OLs were used as supplements to achieve the concentration of 5% in the basal diet. At 12 h of fermentation, methane production decreased in the 5% OLs group compared to that in the control group, but not at 24 h. The proportion of cellulose-degrading bacteria, Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens, tended to increase in the 5% OLs group at 12 h. The amount of ammonia produced was the same as the polymerase chain reaction result for Prevotella ruminicola. At 12 h, the proportion of Prevotella ruminicola was significantly higher in the 5% OLs group. OLs may be used incorporated with protein byproducts or other methane-reducing agents in animal feed.

The challenge of exploiting polyphenols from olive leaves: addition to foods to improve their shelf-life and nutritional value

Olive leaves represent a waste from the olive oil industry which can be reused as source of polyphenols. The most representative phenolic compound of olive leaves is the secoiridoid oleuropein, followed by verbascoside, apigenin-7-O-glucoside, luteolin-7-O-glucoside, and simple phenols. The attention towards these compounds derives above all from the large number of studies demonstrating their beneficial effect on health, in fact olive leaves have been widely used in folk medicine in the Mediterranean regions. Moreover, the growing demand from consumers to replace the synthetic antioxidants, led researchers to conduct studies on the addition of plant bioactives in foods to improve their shelf-life and/or to obtain functional products. The current study overviews the findings on the addition of polyphenol-rich olive leaf extract (OLE) to foods. In particular, the effect of OLE addition on the antioxidant, microbiological and nutritional properties of different foods is examined. Most studies have highlighted the antioxidant effect of OLE in different food matrices, such as oils, meat, baked goods, vegetables, and dairy products. Furthermore, the antimicrobial activity of OLE has been observed in meat and vegetable foods, highlighting the potential of OLE as a replacer of synthetic preservatives. Finally, several authors studied the effect of OLE addition with the aim of improving the nutritional properties of vegetable products, tea, milk, meat and biscuits. Advantages and drawbacks of the different use of OLE were reported and discussed. © 2020 Society of Chemical Industry.

Impact of Fermented or Enzymatically Fermented Dried Olive Pomace on Growth, Expression of Digestive Enzyme and Glucose Transporter Genes, Oxidative Stability of Frozen Meat, and Economic Efficiency of Broiler Chickens

The use of dried olive pomace as complementary energy sources in poultry feed is still limited due to its low protein and high fiber contents. Bioconversion of olive pomace through solid-state fermentation with or without exogenous enzymes is considered as a trial for improving its nutritional value. This study aimed to evaluate the effects of fermented olive pomace with or without enzymatic treatment on the growth, modulations of genes encoding digestive enzymes and glucose transporters, meat oxidative stability, and economic efficiency of broiler chickens. A total of 1400 day-old broiler chicks (Ross 308) were randomly allocated to seven dietary treatments with 10 replicates of 20 birds/replicate. Treatments included control (basal corn-soybean diet) and other six treatments in which basal diet was replaced by three levels (7.5, 15, and 30%) of fermented olive pomace (FOPI) or enzymatically fermented olive pomace (FOPII) for 42 days. The highest body weight gain was observed in groups fed 7.5 and 15% FOPII (increased by 6.6 and 12.5%, respectively, when compared with the control group). Also, feeding on 7.5 and 15% FOPII yielded a better feed conversion ratio and improved the digestibility of crude protein, fat, and crude fiber. The expression of the SGLT-1 gene was upregulated in groups fed FOPI and FOPII when compared with the control group. Moreover, the expression of the GLUT2 gene was elevated in groups fed 7.5 and 15% FOPII. By increasing the levels of FOPI and FOPII in diets, the expression of genes encoding pancreatic AMY2A, PNLIP, and CCK was upregulated (p < 0.05) when compared with the control. Fat percentage and cholesterol content in breast meat were significantly reduced (p < 0.05) by nearly 13.7 and 16.7% in groups fed FOPI and FOPII at the levels of 15 and 30%. Total phenolic and flavonoid contents in breast meat were significantly increased in groups fed 15 and 30% FOPI and FOPII when compared with the control group and even after a long period of frozen storage. After 180 days of frozen storage, the inclusion of high levels of FOP significantly increased (p < 0.05) the levels of glutathione peroxide and total superoxide dismutase and meat ability to scavenge free radical 1,1-diphenyl-2-picrylhydrazyl. Furthermore, the highest net profit and profitability ratio and the lowest cost feed/kg body gain were achieved in groups fed 7.5 and 15% of FOPII, respectively. The results of this study indicated that dietary inclusion of 15% FOPII could enhance the growth performance and economic efficiency of broiler chickens. Moreover, a higher inclusion level of FOPI or FOPII could enhance the quality and increase the oxidative stability of frozen meat and extend the storage time.

Determination of theoretical calculations by DFT method and investigation of antioxidant, antimicrobial properties of olive leaf extracts from different regions

In this study, we studied samples of mature olive leaves from the districts of Incirli Ova within the province of Aydın and the district of Fethiye in Mugla/Turkey. Several processes were carried out on the olive leaves to use them in this study, including drying under different conditions, determination of moisture, extract output, overall determination of phenols, antioxidant activity determination and anti-microbial assays. The chemicals that were used in the study were Folin's reagent and gallic acid for total phenolic assays, DPPH (1,1-diphenyl-2-picrylhydrazyl) and Trolox for antioxidant activity assays and nutrient broth and nutrient agar for antimicrobial testing. In the theoretical part of the study, the structures of oleuropein and Trolox molecules were examined, and their oxidation properties were aimed to be determined and compared to experimental results. According to the results of total phenolic assays, the phenol contents in the olive leaves from Aydın and Mugla were observed to be very close to each other. In the anti-microbial assay, it was observed that the samples of olive leaves from Mugla were more antioxidant than those from Aydın.

The application of polyphenols in food preservation

Polyphenols are a kind of complex secondary metabolites in nature, widely exist in the flowers, bark, roots, stems, leaves, and fruits of plants. Numerous studies have shown that plant-derived polyphenols have a variety of bioactivities due to their unique chemical structure, such as antioxidant, antimicrobial, and prevention of chronic diseases, cardiovascular disease, cancer, osteoporosis, and neurodegeneration. With the gradual rise of natural product development, plant polyphenols have gradually become one of the research hotspots in the field of food science due to their wide distribution in the plants, and the diversity of physiological functions. Owing to the extraordinary antioxidant and antibacterial activity of polyphenols, plant-derived polyphenols offer an alternative to chemical additives used in the food industry, such as oil, seafood, meat, beverages, and food package materials. Based on this, this chapter provides an overview of the potential antioxidant and antibacterial mechanisms of plant polyphenols and their application in food preservation, it would be providing a reference for the future development of polyphenols in the food industry.

Microbiological and Antioxidant Activity of Phenolic Compounds in Olive Leaf Extract

According to many reports, phenolic compounds isolated from olive leaves have very good biological activities, especially antimicrobial. Presently, the resistance of microorganisms to antibiotics is greater than ever. Therefore, there are numerous recent papers about alternative solutions for inhibiting their influence on human health. Olive leaf is studied as an important source of antimicrobials with low cost and used in medicine. Numerous publications on involving green technologies for isolation of active compounds from olive leaves have appeared over the past few decades. The present review reports on current knowledge of the most isolated phenolic compounds from olive leaf extract as well as methods for their isolation and characterization. This paper uses recent research findings with a wide range of study models to describe the antimicrobial potential of phenolic compounds. It also describes the vast range of information about methods for determination of antimicrobial potential focusing on effects on different microbes. Additionally, it serves to highlight the role of olive leaf extract as an antioxidants and presents methods for determination of antioxidant potential. Furthermore, it provides an overview of presence of enzymes. The significance of olive leaves as industrial and agricultural waste is emphasized by means of explaining their availability, therapeutic and nutritional effects, and research conducted on this field.

By-Products from Winemaking and Olive Mill Value Chains for the Enrichment of Refined Olive Oil: Technological Challenges and Nutraceutical Features

A growing body of literature is available about the valorization of food by-products to produce functional foods that combine the basic nutritional impact with the improvement of the health status of consumers. In this context, this study had two main objectives: (i) An innovative multistep extraction process for the production of a refined olive oil enriched with phenolic compounds (PE-ROO) extracted from olive pomace, olive leaves, or grape marc was presented and discussed. (ii) The most promising PE-ROOs were selected and utilized in in vitro and in vivo trials in order to determine their effectiveness in the management of high fat diet-induced-metabolic syndrome and oxidative stress in rats. The best results were obtained when olive leaves were used as source of phenols, regardless of the chemical composition of the solvent utilized for the extraction. Furthermore, while ethanol/hexane mixture was confirmed as a good solvent for the extraction of phenols compounds soluble in oil, the mix ROO/ethanol also showed a good extracting power from olive leaves. Besides, the ROO enriched with phenols extracted from olive leaves revealed an interesting beneficial effect to counteract high fat diet-induced-metabolic disorder and oxidative stress in rats, closely followed by ROO enriched by utilizing grape marc.

Natural Deep Eutectic Solvent as Extraction Media for the Main Phenolic Compounds from Olive Oil Processing Wastes

In this new century, sustainable development challenges chemical sciences to develop new and clean technological processes. The agri-food industry produces significant quantities of waste, raising significant economic and environmental concerns. Food waste valorization using environmentally friendly procedures is of increasing importance. This study describes the use of several Natural Deep Eutectic Solvents (NADESs) for the microwave-assisted extraction (MAE) of valuable bioactive phenolic compounds from olive oil processing wastes. The extracted samples were characterized by liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF/MS) analysis and the quantification of the phenolic compounds was performed by HPLC analysis. The obtained data were compared with those obtained using water as the solvent in the same extraction conditions. The extraction process is nontoxic, simple and selective and meets most of the criteria to be considered as a sustainable process, with the solvents arising directly from nature.

Journal of Food Quality Evaluation of Effect of Extraction Solvent on Selected Properties of Olive Leaf Extract

The quest for natural preservatives and functional foods with health benefits has seen an increasing demand for natural products having therapeutic value. Herein, we investigated the influence of ethanol, methanol, acetone (50%, 70%, and 90% v/v), and distilled water on selected properties of olive leaf extract and determined the yield, total phenolic content (TPC), antioxidant activity, and antimicrobial activity. Extracts were analyzed for their oleuropein, hydroxytyrosol, and tyrosol contents by high-performance liquid chromatography (HPLC). The highest extraction yield of 20.41% was obtained when using 90 vol% methanol, while the highest total polyphenol contents of 232 and 231 mggallic-acid-equivalent/100 g were obtained for 90 vol% methanol and 90 vol% ethanol, respectively. Antioxidant activity was determined using the α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging assay, by determining the ferric reducing antioxidant power (FRAP), and using the Fe2+-chelating activity assay, which provided the highest values when 90 vol% methanol was used (33.84%, 0.75, and 12.91%, respectively). HPLC analysis showed that the highest oleuropein contents corresponded to the extracts obtained using 90 and 70 vol% methanol (26.10 ± 0.20 and 24.92 ± 1.22 g/L, respectively), and the highest antimicrobial activity was observed for 90 vol% methanol and distilled water. Olive leaf extracts using 90 vol% methanol had high levels of polyphenols and were highly antioxidant and antimicrobial. The results of this study facilitate the commercial applications of natural extracts with antioxidant and antibacterial activities and are expected to establish a foundation for further optimization studies.

Genetic and genomic approaches to address rapid rancidity of rice bran

Rice bran is an invaluable by-product of paddy processing industry. It is rich in minerals, protein, lipids, and crude fiber. In addition, it also possesses compounds with anti-oxidant, anti-allergic, anti-diabetic, and anti-cancer properties. It forms a basis for the extraction of rice bran oil and preparation of various functional foods with health benefits and potential to prevent chronic health issues. Nevertheless, the rapid deterioration of bran upon storage acts as a major limitation in exploiting the full potential of rice bran. In this review, we have discussed three strategies to address rapid rancidity of rice bran and enhance its shelf life and storability vis-a-vis emphasizing the importance of rice bran in terms of its nutritional composition. One strategy is through exploitation of the null mutations in the genes governing lipases and lipoxygenases leading to nonfunctional enzymes (enzyme deficient approach), another strategy is through reducing the PUFA content that is more prone to oxidation (substrate deficient approach) and a third strategy is through enhancing the antioxidant content that effectively terminate the lipid peroxidation by donating the hydrogen atom.

By-Products of Olive Oil in the Service of the Deficiency of Food Antioxidants: The Case of Butter

Further downstream in the olive oil extraction process, the Mediterranean Basin faces a serious environmental threat caused by olive waste. Despite their polluting profile, olive waste is considered to be a very rich source of natural antioxidants, such as polyphenols. In this study, the latter was valued as a source of natural antioxidants and compared with a synthetic antioxidant ascorbic acid. Concentrations of 2, 4, 6, and 8 mg of the olive mill waste water as well as pomace and ascorbic acid are added to butter (commercial butter) and placed under storage conditions in the oven (accelerated test: 60°C) for 3 months. The alteration of the butter used was followed by determination of the peroxide value and acidity and microbiological analysis. The results obtained show that butters containing olive by-products have undergone less marked oxidative deterioration than those of the control (without additives). The best oxidative stability of butter was achieved by adding 80 mg/kg of butter, a result comparable with that obtained by adding ascorbic acid.

Chemical composition, antioxidant activities, in an allergic asthma model, of Olea europaea L. leaf extracts from Collo (Skikda, Algeria)

This study is an attempt to characterize the chemical composition and antioxidant activity of olive leaves variety (namely Bouricha variety) that is very widespread in the East of Algeria. The aqueous extract (AE) of leaves was initially analyzed for its phenolic profile. Using the liquid chromatography coupled to tandem mass spectrometry analysis, it was possible to identify the predominant components in the AE of the leaves. This extract was hydrolyzed with acid and gave hydroxytyrosol (HT). AE and HT were evaluated for their 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity, ferric reducing antioxidant power and total antioxidant activity by phosphomolybdenum method. The antioxidant and anti-asthmatic activities of these extracts were examined in a model of experimental asthma in Wistar rats. For measuring the intensity of the airway inflammation, oxidative stress parameters were analyzed in lungs and a histological study of this tissue was performed. The obtained results showed that the sensitization of the ovalbumin (OVA) group induced lung inflammation and severe lipid peroxidation (LPO) revealed by a significant increase in malondialdehyde (MDA) levels and a decrease in the non-enzymatic and enzymatic antioxidant systems. However, the administration of AE and HT extracts significantly improved the antioxidant state in asthma disease and provided evidence for the relation between phenolic compounds and the high antioxidant activity of olive leaves extracts, especially HT more than AE.

Physico-Chemical, Microbiological and Sensory Evaluation of Ready-to-Use Vegetable Pâté Added with Olive Leaf Extract

The shelf-life extension implicates the reduction of food waste. Plant polyphenols can have a crucial role in the shelf-life extension of foods. Olive leaf extract (OLE) is rich in phenolic compounds such as oleuropein, which is well-known for its antioxidant properties. Physico-chemical, microbiological and sensory aspects of non-thermally stabilized olive-based pâté fortified with OLE at concentrations of 0.5 (EX0.5) and 1 mg kg⁻¹ (EX1) were investigated. These samples were compared with olive-based pâté fortified with the synthetic antioxidant BHT (butylated hydroxytoluene) and with a control sample (CTR) without antioxidants. No sensory defects were perceived in all samples, even if a more intense typical olive flavour was perceived in samples containing OLE compared to those containing BHT and CTR. This result was confirmed by significantly higher levels of 2-methylbutanal and 3-methylbutanal in samples containing OLE compared to CTR and BHT. Moreover, the main microbial groups registered a significant loss of 0.5–1 logarithmic cycles in samples containing OLE, especially in EX1. The results of the present study indicate the potentiality of using OLE as natural preservatives in non-thermally stabilized olive-based pâté, since some spoilage-related microbial groups were negatively affected by the addition of OLE at the highest concentration.

Olive Leaf Addition Increases Olive Oil Nutraceutical Properties

The aim of the present research was to study the effects of olive leaf addition (0 and 3%) on the major antioxidants and the antioxidant activity of Neb Jmel and Oueslati olive oils. Olives and leaves of the two Tunisian varieties were harvested during the 2016/2017 crop season. Both leaves and oils were characterised for their concentrations in phenolics, tocopherols and antioxidant power. Other parameters such as free acidity, peroxide value, chlorophyll and carotenoid concentrations were also taken into consideration. Compared to Oueslati, the Neb Jmel oil showed a lower free acidity (50%) and peroxide value (5.6-fold), and higher chlorophyll (1.6-fold), total phenolics (1.3-fold), flavonoid (3-fold) and oleuropein derivative (1.5-fold) concentrations, in addition to an increased antioxidant activity (1.6-fold). Leaf addition promoted a significant increment in total chlorophyll, α-tocopherol and phenolics in both varieties, above all in Oueslati oil, due to a higher abundance of bioactive constituents in the corresponding leaves. In particular, chlorophyll and carotenoid concentrations reached values twice higher than in Neb Jmel leaves, and flavonoids and oleouperin derivatives were three-fold higher. This prevented the oxidation and the formation of peroxides, reducing the peroxide value of the fortified oil to the half. The results provide evidence on the performance of the Tunisian Neb Jmel and Oueslati varieties, showing that their oils present a chemical profile corresponding to the extra virgin olive oil category and that, after leaf addition, their nutritional value was improved.

Olive Leaves Extract from Algerian Oleaster (Olea europaea var. sylvestris) on Microbiological Safety and Shelf-life Stability of Raw Halal Minced Beef during Display

Oleaster (wild olive tree) by-products represent a renewable and low-cost source of biopolyphenols. Leaf extracts (sylv.OLE) of Algerian oleaster, locally called a'hachad (Olea europaea subsp. europaea var. sylvestris), were applied at 1 and 5% (v/w) to raw Halal minced beef (HMB) in order to test its safety and shelf-life prolongation during retail/display. The total phenolic compound content in the extract was 198.7 ± 3.6 mg gallic acid equivalent. Ten compounds were identified in the sylv.OLE by High Performance Liquid Chromatography/Diode Array Detector (HPLC/DAD), of which oleuropein was the most abundant (43.25%). Samples treated with 5% sylv.OLE had significantly higher antimicrobial and antioxidant effects than those treated with 1% extract (p < 0.05). The addition of sylv.OLE reduced psychrotrophic counts as well as the level of pathogens (Salmonella enterica ser. Enteritidis and Shiga toxin-producing Escherichia coli O157:H7). A thiobarbituric acid reactive substance (TBARS) value of 2.42 ± 0.11 was reached throughout six days of retail/display in control samples, while the addition of 5% sylv.OLE reduced TBARS value by 58% (p < 0.05). The presence of sylv.OLE at the tested concentrations did not negatively influence the overall acceptability and bitterness of HMB.

Lipid Characterization of Chinese Wild Hazelnuts (Corylus mandshurica Maxim.)

To develop and use the hazelnut, the main composition, and the physicochemical characteristics, fatty acid compositions, triacylglycerol (TAG) distribution and tocol contents of Hazelnut (Corylus mandshurica Maxim.) which growing in Changbai mountain of Jilin province (HO1) and Anshan city of Liaoning province (HO2) in China were investigated, and the comparative study between the two hazelnut oils and American hazelnut / Turkish hazelnut were also explored. The content of crude lipid and protein in HO1 and HO2 were approximately 54% and 17%, 55% and 16%, respectively. The two hazelnut oils were abundant in unsaturated fatty acids, with the primary unsaturated fatty acids were oleic acid (78%-80%) and linoleic acid (14-16%), which accounted for above 90% of the oils. Therefore, both of the hazelnut oils were important sources of essential fatty acid. In addition, the main saturated fatty acid of the two hazelnut oils were palmitic acid (3%) and stearic acid (1-2%). The main triacylglycerols (TGA) profile were dioleolinolein (OOL), oleodilinolein (OLL) and triolein (OOO). The contents of tocol were 574.44 μg/g, 647.49 μg/g oil in HO1 and HO2, respectively, both of them were higher than that of grape seed oils (454 μg/g), olive oils (209 μg/g) and walnut oils (255 μg/g). The total phytosterol contents were over 2000μg/g and β-sitosterol was the most predominant sterol in two oils.

Olive leaf extracts for shelf life extension of salmon burgers

In this work, the effect of the addition of olive leaf extracts on the quality of vacuum-packed salmon burgers stored at 4 ℃ during 16 days has been studied. Olive leaf extract and its hydrolysate were initially characterized and then incorporated to salmon burgers. A shelf life study was conducted in three different batches (control, olive leaf extract, and hydrolyzed olive leaf extract burgers). Among the chemical indices determined, total volatile base nitrogen values were lower in hydrolyzed olive leaf extract and olive leaf extract burgers than in control samples. Lipid oxidation was lower in salmon burger with olive leaf extract. Salmon mince treated with hydrolyzed olive leaf extract showed lower microbial counts during the whole study, which extended the shelf life of the fish product. Therefore, the potential of olive leaf extracts to preserve salmon burgers during cold storage has been demonstrated.

Safety Assessment of Plant-Derived Fatty Acid Oils

The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of 244 plant-derived fatty acid oils as used in cosmetics. Oils are used in a wide variety of cosmetic products for their skin conditioning, occlusive, emollient, and moisturizing properties. Since many of these oils are edible, and their systemic toxicity potential is low, the review focused on potential dermal effects. The Panel concluded that the 244 plant-derived fatty acid oils are safe as used in cosmetics.