The occurrence and bioactivity of polyphenols in Tunisian olive products and by-products: a review

Polyphenols have become a subject of intense research because of their perceived beneficial effects on health due to their anticarcinogenic, antiatherogenic, anti-inflammatory, and antimicrobial activities. It is well known that olives and their derivatives are rich in phenolic substances with pharmaceutical properties, some of which exert important antioxidant effects. The characterization and quantification of their polyphenol composition is one of the first steps to be taken in any evaluation of the putative contribution of the olive to human health. This review is concerned with polyphenols in Tunisian olive (Olea europaea L.) products (fruit and oil) and some by-products (leaves and olive-mill wastewater) with an emphasis on the analytical methods used, as well as the biological activities described in recent years.     

Nutraceutical potential of olive pomace: insights from cell-based and clinical studies

Olive oil production yields a substantial volume of by-products, constituting up to 80% of the processed fruits. The olive pomace by-product represents a residue of significant interest due to the diverse bioactive compounds identified in it. However, a thorough characterization and elucidation of the biological activities of olive pomace are imperative to redirect its application for functional food, nutraceutical, and pharmaceutical purposes both for animals and humans. In this review, we examine data from experimental models, including immortalized human vascular endothelial cells, human corneal and conjunctival epithelial cells, human colorectal adenocarcinoma cells, non-tumorigenic human hepatoma cells, and murine macrophages alongside clinical trials. These studies aim to validate the safety, nutritional value, and pharmacological effects of olive pomace. In vitro studies suggest that biophenols extracted from olive pomace possess antioxidant, anti-inflammatory, and antiproliferative properties that could be beneficial in mitigating cardiovascular disorders, particularly atherosclerosis, hepatosteatosis, and dry-eye disease. Protective effects against dry-eye disease were confirmed in a mouse model assay. Olive pomace used in the feed for fish and poultry has demonstrated the ability to enhance animals' immunity and improve nutritional quality of meat and eggs. Human clinical trials are scarce and have revealed minimal biological changes following the consumption of olive pomace-enriched foods. However, alterations in certain biomarkers tentatively suggest cardioprotective properties. The review underscores the value of olive pomace while addressing potential drawbacks and future perspectives, with a specific focus on the need for further investigation into the animal feed and human nutritional properties of olive pomace. © 2024 Society of Chemical Industry.     

The utilisation solutions of olive mill by-products in the terms of sustainable olive oil production: a review

Despite the high economic and nutritional value as major positive aspects, olive oil production has an unfavourable side, which is the negative environmental impact caused by the generation of significant amounts of liquid and solid wastes. Therefore, the implementation of sustainable technologies to add value to the olive oil production process is a matter of great interest. This study aimed to review novel solutions dealing with the utilisation of olive oil production by-products while taking into account sustainable waste management options. The most promising technologies for the production of high-added value products from olive oil production by-products have been described with a special attention to the sustainable nonthermal technologies for the extraction of bioactive phenolic compounds, and the key findings of such investigations were reviewed. All described technologies are environmentally friendly and show great potential. Nevertheless, further researches are required to optimise and increase their applicability.     

Pesticide residues in washing water of olive oil mills: effect on olive washing efficiency and decontamination proposal

BACKGROUND: Washing olives in the olive oil mill (a commonly used preliminary step to remove foreign materials and leaves) can help to remove pesticide residues, especially herbicides that are present in olives due to contamination either during application or as a consequence of contact with contaminated soil. The aim of the present work was the study of washing efficacy during washing cycles, i.e., from the beginning of the cycle until the water was changed. RESULTS: Four active ingredients, namely diuron, oxyfluorfen, terbuthylazine and endosulfan (α and β isomers) as well as the latter's degradation product endosulfan sulfate, were the most frequently found pesticides in raw olives after harvest. At the beginning of the washing cycle, diuron, terbuthylazine and oxyfluorfen residues were effectively removed from olives. However, progressive water contamination with pesticide residues decreased the efficiency of the washing step, specially for diuron and terbuthylazine residues. CONCLUSION: A decontamination method to enable water recycling in olive oil mills was proposed and optimized. It employed FeCl₃ as coagulant and active charcoal as adsorbent, and was effective in removing both suspended solids and pesticide residues. Copyright © 2008 Society of Chemical Industry     

Virgin olive oil (VOO) production in Tunisia: The commercial potential of the major olive varieties from the arid Tataouine zone

The commercial potential of olive oils from three consecutive crop years, derived from the main autochthonous olive varieties Chemlali Tataouine, Fakhari Douirat, Zarrazi Douirat and Dhokar Douirat grown in the arid region of Tataounine (Tunisia) was examined with regards to stability and nutrition aspects. Several characteristics such as fatty acid composition, the extremely high phenol-type antioxidant content, and the low levels of green pigments suggested that these oils, the only fat source for the local people, are of promising composition. Efforts to develop commercial products from these varieties could improve antioxidant intake of the local population. The introduction of Good Manufacturing Practices is a prerequisite so that the quality observed for oils obtained by an Abencor system to be achieved also in real life. This can be feasible through appropriate oleoculture, which is often the only viable agricultural activity in remote arid regions such as Tataouine.     

A critical review on the use of artificial neural networks in olive oil production,characterization and authentication

Artificial neural networks (ANN) are computationally based mathematical tools inspired by the fundamental cell of the nervous system, the neuron. ANN constitute a simplified artificial replica of the human brain consisting of parallel processing neural elements similar to neurons in living beings. ANN is able to store large amounts of experimental information to be used for generalization with the aid of an appropriate prediction model. ANN has proved useful for a variety of biological, medical, economic and meteorological purposes, and in agro-food science and technology. The olive oil industry has a substantial weight in Mediterranean's economy. The different steps of the olive oil production process, which include olive tree and fruit care, fruit harvest, mechanical and chemical processing, and oil packaging have been examined in depth with a view to their optimization, and so have the authenticity, sensory properties and other quality-related properties of olive oil. This paper reviews existing literature on the use of bioinformatics predictive methods based on ANN in connection with the production, processing and characterization of olive oil. It examines the state of the art in bioinformatics tools for optimizing or predicting its quality with a view to identifying potential deficiencies or aspects for improvement.     

Current technologies and new insights for the recovery of high valuable compounds from fruits by-products

The recovery of high valuable compounds from food waste is becoming a tighten issue in food processing. The large amount of non-edible residues produced by food industries causes pollution, difficulties in the management, and economic loss. The waste produced during the transformation of fruits includes a huge amount of materials such as peels, seeds, and bagasse, whose disposal usually represents a problem. Research over the past 20 years revealed that many food wastes could serve as a source of potentially valuable bioactive compounds, such as antioxidants and vitamins with increasing scientific interest thanks to their beneficial effects on human health. The challenge for the recovery of these compounds is to find the most appropriate and environment friendly extraction technique able to achieve the maximum extraction yield without compromising the stability of the extracted products. Based on this scenario, the aim of the current review is twofold. The first is to give a brief overview of the most important bioactive compounds occurring in fruit wastes. The second is to describe the pro and cons of the most up-to-dated innovative and environment friendly extraction technologies that can be an alternative to the classical solvent extraction procedures for the recovery of valuable compounds from fruit processing. Furthermore, a final section will take into account published findings on the combination of some of these technologies to increase the extracts yields of bioactives.     

Effect of extraction systems and cultivar on the quality of virgin olive oils

This research was carried out to compare the effects of two industrial scale processes (super press and triple phase systems) and a traditional Tunisian family-sized operation with laboratory milling for two varieties of olives: Chemlali and Chemchali. Analyses of the effect of the extraction system, on the oils' characteristics, revealed statistically significant differences in some parameters, mainly in antioxidant compounds ( P  < 0.05). Major fatty acids presented significant differences ( P  < 0.05) with respect to the cultivar kind (55.93% vs. 72.21%). Oxidative stability of Chemchali was nearly two times higher than Chemlali (94.58 vs. 50.37 day kg⁻¹). Results appear to confirm the general consensus that Chemchali oils are of much higher quality compared with the tolerable quality of Chemlali . The traditional method is a valid form of producing high quality oil with very high stability (48.87 and 109.07 day kg⁻¹ for Chemlali and Chemchali oil, respectively). However, industrial mills showed that triple-phase scale could cause considerable loss in polyphenols. Finally, olive oil quality is mainly dependant on the quality of the olives and on the extraction method.     

Advance technology in virgin olive oil production from traditional and de-stoned pastes: Influence of the introduction of a heat exchanger on oil quality

An experimental investigation was carried out to evaluate the quality of virgin olive oils obtained when a de-stoner were used for the olive paste preparation in comparison to the use of a traditional stone mill. In order to improve the slightly differences of oil yields due to the use of the de-stoner also a heat exchanger has been introduced in the processing line. The experimental data showed that resistance to the oxidation, total phenols and pleasant volatile compounds were higher in the de-stoned olive oils than in the oils obtained from the whole paste. Resistance to oxidation was assessed by Rancimat method and showed a positive correlation with the amount of total phenols.     

Agro-industrial potential of the mango peel based on its nutritional and functional properties

The mango peel represents from 15% to 20% of the total weight of the fruit. The aim of this review is to discuss the nutritional, functional, and nutraceutical properties of mango peel. It also shows several ways to add value to the mango peels, and their uses. Mango peel contains considerable content of antioxidants and dietary fiber. The mango peel offers a range of possibilities to develop value-added products. By-products from the agro-industrial processing of mangos can potentially make a significant contribution to the design of natural products rich in dietary fiber for widespread consumption. Additionally, food rich in soluble dietary fiber from mango peels could be designed for diabetic persons, since the mango peel reduces the speed with which glucose reaches the blood. Optimal extraction methods and drying technologies that do not impair the functional properties need to be further investigated. Economic, nutritional, and environmental benefits could be obtained with the proper use of this processing by-product.     

The influence of the malaxation temperature on the activity of polyphenoloxidase and peroxidase and on the phenolic composition of virgin olive oil

The effect of the malaxation temperature under sealed conditions on the qualitative and quantitative composition of the phenolic compounds in virgin olive oils produced from four Italian cultivars was assessed for two atmospheric conditions. In both cases, the results show a positive relationship between temperature and the concentration of the derivatives of the secoiridoid aglycones; the effect of the temperature on the oxidoreductases that promote oxidation (polyphenoloxidase and peroxidase) was investigated to determine their optimal temperatures and thermal stability. While olive peroxidase (POD) showed the highest activity at 37 °C and high stability in the temperature range tested, polyphenoloxidase (PPO) exhibited the optimum activity at approximately 50 °C, but showed low stability at 40 °C, with a large variation in stability according to the olive cultivar. These results may contribute to an understanding of the increase in the phenol concentration found in virgin olive oils obtained following higher temperatures of malaxation.     

Physicochemical characteristics,bioactive compounds and industrial applications of mango kernel and its products: A review

Mango (Mangifera indica L.) is a fruit plant of family Anacardiaceae, widely grown all over the world, and is a very popular fruit in the world market. Mango fruit is the second most traded tropical fruit and fifth in terms of production globally. Large quantities of mango processing coproducts are generated (peels and seeds), which usually are discarded as waste, yet are a potential source of fat, protein, carbohydrate, and certain bioactive compounds. Mango kernel is a remarkably rich source of macronutrients and micronutrients including calcium, potassium, magnesium, phosphorus, and vitamins A, E, K, and C. Phytochemicals with a notable therapeutic potential such as tocopherols, phytosterols, carotenoids, polyphenols (gallotannins, flavonols, benzophenone derivatives, mangiferin, homomangiferin, isomangiferin, anthocyanins, kaempferol, and quercetin), and phenolic acids (4‐caffeoylquinic acids, caffeic, coumaric, ellagic, gallic, and ferulic acid) are reported. The phytochemicals have high antioxidant, antimicrobial, anticancer, and, antiproliferation activities and could be used for food, cosmetic, and pharmaceutical applications. The nutritional composition of mango kernel constitutes 32.34% to 76.81% carbohydrate, 6% to 15.2% fat, 6.36% to 10.02% protein, 0.26% to 4.69% crude fiber, and 1.46% to 3.71% ash on a dry weight basis. The nutritional profile of the kernel suggests its usability as a food ingredient in the development of value‐added products such as mango kernel oil, mango kernel butter, mango kernel flour, and biofilms among other diverse products. This comprehensive systematic review explores mango kernel as a potential and novel food ingredient to meet the needs of a health‐conscious population. The review also provides a remedy to waste management and environmental pollution.     

The potential of different techniques for volatile compounds analysis coupled with PCA for the detection of the adulteration of olive oil with hazelnut oil

This paper investigates the effectiveness of three rapid methods of volatile compounds analysis with subsequent principal component analysis (PCA) treatment of data for differentiation between virgin olive oil samples adulterated with hazelnut oil. Tested methods included comparison of chromatograms of volatiles obtained using SPME-fast GC-FID, volatiles analysis by electronic nose based on MOS sensors (HS-Enose), and by direct coupling of SPME to MS (SPME-MS). Volatile compounds were analyzed also by SPME-GC/MS technique. Data obtained as a result of SPME-GC/MS was subjected to PCA. SPME-GC–MS analysis with subsequent PCA yielded good results, however being time consuming. The three methods of analysis of volatiles, with subsequent PCA treatment of data, allowed detection of olive oil adulteration with different contents of hazelnut oil ranging from 5 to 50% (v/v).     

Technological,nutritional and sensory properties of pasta fortified with agro-industrial by-products: a review

Reducing food waste is a priority to move towards more sustainable food systems. Since agro-food by-products are often rich in healthy compounds, such as fibre, phytochemicals, protein, fatty acids, vitamins and minerals, the waste valorisation could move through their transformation into ingredients useful for the formulation of functional foods. Pasta is a staple food widely consumed all over the world representing an optimal carrier for nutrients delivery. The incorporation of ingredients of a high added value obtained by agro-industrial by-products in pasta can improve its nutritional value and provides several health benefits. At the same time, the inclusion of new ingredients could modify the physical, chemical and textural properties determining the change of the organoleptic characteristics of fortified pasta, affecting its acceptability. Thus, the preparation of new pasta formulations with high nutritional properties, good technological and sensory characteristics represents a challenge for the food industry.     

Understanding the potential benefits of thyme and its derived products for food industry and consumer health: From extraction of value-added compounds to the evaluation of bioaccessibility,bioavailability, anti-inflammatory,and antimicrobial activities

ABSTRACT

Natural bioactive compounds isolated from several aromatic plants have been studied for centuries due to their unique characteristics that carry great importance in food, and pharmaceutical, and cosmetic industries. For instance, several beneficial activities have been attributed to some specific compounds found in Thymus such as anti-inflammatory, antioxidant, antimicrobial, and antiseptic properties. Moreover, these compounds are classified as Generally Recognized as Safe (GRAS) which means they can be used as an ingrident of may food producs. Conventional extraction processes of these compounds and their derived forms from thyme leaves are well established. Hoewever, they present some important drawbacks such as long extraction time, low yield, high solvent consumption and degradation thermolabile compounds. Therefore, innovative extraction techniques such as ultrasound, microwave, enzyme, ohmic and heat-assisted methods can be useful strategies to enhance the exytraction yield and to reduce processing temperature, extraction time, and energy and solvent consumption. Furthermore, bioaccessibility and bioavailability aspects of these bioactive compounds as well as their metabolic fates are crucial for developing novel functional foods. Additionally, immobilization methods to improve stability, solubility, and the overall bioavailability of these valuable compounds are necessary for their commercial applications. This review aims to give an overall perspective of innovative extraction techniques to extract the targeted compounds with anti-inflammatory and antimicrobial activities. Moreover, the bioaccessi-bility and bioavailability of these compounds before and after processing discussed. In addition, some of the most important characteristics of thyme and their derived products discussed in this paper.     

Microwave heating of different commercial categories of olive oil: Part I. Effect on chemical oxidative stability indices and phenolic compounds

The effect of microwave heating of extra virgin olive oil (EVOo), olive oil (Oo) and pomace olive oil (Po) in domestic appliances, was investigated in terms of chemical oxidative indices (peroxide, p-anisidine and Totox values), free acidity, water content, total phenol content and different classes of phenolic compounds.     

Effect of oxygen reduction during malaxation on the quality of extra virgin olive oil (Cv. Carboncella) extracted through “two-phase” and “three-phase” centrifugal decanters

Quality and composition of virgin olive oil (VOO) are strictly dependent on complex processes that take place during the olive fruit crushing and malaxation of the olive paste. In this work, modulation of O₂ levels within malaxation chambers (R1: unmodified atmosphere; R2: oxygen: 12.73–4.64 kPa from the beginning to the end of malaxation; R3: 10.46–2.27 kPa; R4: 9.87–0.69 kPa) in two continuous “two-phase” and “three-phase” oil extraction plants was performed. Combined effects on the biosynthesis of nutritionally bioactive molecules and aroma volatiles and on the resulting sensory properties of the produced oils were investigated. Results showed that the type of oil extraction plant markedly affected the level of the phenolic compounds in the oil (and the related sensory attributes of bitter, pungency, astringency and bitter and pungency persistence). Reduction of O₂ concentration in the malaxing chamber, while having a minor impact on the presence of phenolic compounds, significantly affected the formation of all the examined volatiles. Particularly, lowered levels of oxygen hindered the formation of lipoxygenase derived volatiles weakening odours and flavours of artichoke, fresh fruity, and fresh cut grass.     

Recent trends for the employment of jumbo squid (Dosidicus gigas) by-products as a source of bioactive compounds with nutritional,functional and preservative applications: a review

Only 50%–60% of total seafood catch is used for human consumption, seafood processing being considered as one of the main sources of by-products. Among marine species, jumbo squid (JS; Dosidicus gigas) represents the most important squid fishery, showing an increasing economic interest in many countries. As for any other marine species, the regular cleaning, dressing and processing produce high quantities of by-products (skin, head, fins, viscera, tentacles, unclaimed mantle, etc.) that are rich in many nutrients (proteins, lipids, minerals, vitamins, enzymes, biopolymers, etc.). This review compiles information about extraction and employment of JS by-products with the aim of enhancing their economic value and reduce environmental drawbacks. A special emphasis is given to the relevance in developing methods susceptible to transform by-products into useful and profitable products susceptible to be applied in several industries such as food, medicine, agrochemical or pharmaceutical. Future possible trends for widening this profitable use are mentioned.