A Quick, Green and Simple Ultrasound-Assisted Extraction for the Valorization of Antioxidant Phenolic Acids from Moroccan Almond Cold-Pressed Oil Residues

Ultrasonic Processing of Food Waste to Generate Value-Added Products

Ultrasonic processing has a great potential to transform waste from the food and agriculture industry into value-added products. In this review article, we discuss the use of ultrasound for the valorisation of food and agricultural waste. Ultrasonic processing is considered a green technology as compared to the conventional chemical extraction/processing methods. The influence of ultrasound pre-treatment on the soluble chemical oxygen demand (SCOD), particle size, and cell wall content of food waste is first discussed. The use of ultrasonic processing to produce/extract bioactives such as oil, polyphenolic, polysaccharides, fatty acids, organic acids, protein, lipids, and enzymes is highlighted. Moreover, ultrasonic processing in bioenergy production from food waste such as green methane, hydrogen, biodiesel, and ethanol through anaerobic digestion is also reviewed. The conversion of waste oils into biofuels with the use of ultrasound is presented. The latest developments and future prospective on the use of ultrasound in developing energy-efficient methods to convert food and agricultural waste into value-added products are summarised.

Differential Flavonoid and Other Phenolic Accumulations and Antioxidant Activities of Nymphaea lotus L. Populations throughout Thailand

Nymphaea lotus L. is a potential plant in the Nymphaeaceae family that is well-recognized as an economic and traditional medicinal plant in Thailand and other countries. Its pharmacological and medicinal effects have been confirmed. However, there is no study going deeper into the population level to examine the phytochemical variation and biological activity of each population that benefits phytopharmaceutical and medical applications using this plant as raw material. This study was intensely conducted to complete this important research gap to investigate the flavonoid profiles from its floral parts, the stamen and perianth, as well as the antioxidant potential of the 13 populations collected from every floristic region by (1) analyzing their flavonoid profiles, including the HPLC analysis, and (2) investigating the antioxidant capacity of these populations using three assays to observe different antioxidant mechanisms. The results indicated that the northeastern and northern regions are the most abundant floristic regions, and flavonoids are the main phytochemical class of both stamen and perianth extracts from N. lotus. The stamen offers higher flavonoids and richer antioxidant potential compared with the perianth. This finding is also the first completed report at the population level to describe the significant correlation between the phytochemical profiles in floral parts extracts and the main antioxidant activity, which is mediated by the electron transfer mechanism. The results from the Pearson correlation coefficients between several phytochemicals and different antioxidant assessments highlighted that the antioxidant capability of these extracts is the result of complex phytochemical combinations. The frontier knowledge from these current findings helps to open up doors for phytopharmaceutical industries to discover their preferred populations and floral parts that fit with their targeted products.

Flavonoid Profiles and Antioxidant Potential of Monochoria angustifolia (G. X. Wang) Boonkerd & Tungmunnithum, a New Species from the Genus Monochoria C. Presl

Plants of the genus Monochoria have long been utilized in food, cosmetics, and traditional herbal treatments. Thailand has the highest species diversity of this genus and a new member, Monochoria angustifolia (G. X. Wang) Boonkerd & Tungmunnithum has been recently described. This plant is called “Siam Violet Pearl” as a common name or “Khimuk Si Muang Haeng Siam” as its vernacular name with the same meaning in the Thai language. Despite their importance, little research on Monochoria species has been conducted. This study, thus, provides the results to fill in this gap by: (i) determining flavonoid phytochemical profiles of 25 natural populations of M. angustifolia covering the whole floristic regions in Thailand, and (ii) determining antioxidant activity using various antioxidant assays to investigate probable mechanisms. The results revealed that M. angustifolia presents a higher flavonoid content than the outgroup, M. hastata. Our results also revealed that flavonoids might be used to investigate Monochoria evolutionary connections and for botanical authentication. The various antioxidant assays revealed that M. angustifolia extracts preferentially act through a hydrogen atom transfer antioxidant mechanism. Pearson correlation analysis indicated significant correlations, emphasizing that the antioxidant capacity is most probably due to the complex action of several phytochemicals rather than that of a single molecule. Together, these results showed that this new species provide an attractive alternative starting material with phytochemical variety and antioxidant potential for the phytopharmaceutical industry.

Phytochemical Diversity and Antioxidant Potential of Natural Populations of Nelumbo nucifera Gaertn. throughout the Floristic Regions in Thailand

Asian lotus has long been consumed as a food and herbal drug that provides several health benefits. The number of studies on its biological activity is significant, but research at the population level to investigate the variation in phytochemicals and biological activity of each population which is useful for a more efficient phytopharmaceutical application strategy remains needed. This present study provided the frontier results to fill-in this necessary gap to investigating the phytopharmaceutical potential of perianth and stamen, which represent an important part for Asian traditional medicines, from 18 natural populations throughout Thailand by (1) determining their phytochemical profiles, such as total contents of phenolic, flavonoid, and anthocyanin, and (2) determining the antioxidant activity of these natural populations using various antioxidant assays to examine different mechanisms. The result showed that Central is the most abundant floristic region. The stamen was higher in total phenolic and flavonoid contents, whereas perianth was higher in monomeric anthocyanin content. This study provided the first description of the significant correlation between phytochemical contents in perianth compared with stamen extracts, and indicated that flavonoids are the main phytochemical class. This analysis indicated that the stamen is a richer source of flavonoids than perianth, and provided the first report to quantify different flavonoids accumulated in stamen and perianth extracts under their native glycosidic forms at the population level. Various antioxidant assays revealed that major flavonoids from N. nucifera prefer the hydrogen atom transfer mechanism when quenching free radicals. The significant correlations between various phytochemical classes and the different antioxidant tests were noted by Pearson correlation coefficients and emphasized that the antioxidant capability of an extract is generally the result of complex phytochemical combinations as opposed to a single molecule. These current findings offer the alternative starting materials to assess the phytochemical diversity and antioxidant potential of N. nucifera for phytopharmaceutical sectors.

Effect of Traditional Cooking and In Vitro Gastrointestinal Digestion of the Ten Most Consumed Beans from the Fabaceae Family in Thailand on Their Phytochemicals, Antioxidant and Anti-Diabetic Potentials

The edible beans in Fabaceae have been used for foods and medicines since the ancient time, and being used more and more. It is also appeared as a major ingredient in dairy cooking menu in many regions including Thailand, a rich biodiversity country. Many studies reported on health benefits of their flavonoids, but there is no report on the effect of cooking on phytochemical profile and pharmacological potentials. Thus, this present study aims to complete this knowledge, with the 10 most consumed Fabaceae beans in Thailand, by determining the impact of traditional cooking and gastrointestinal digestion on their phytochemicals, their antioxidant and anti-diabetic activities using different in vitro and in cellulo yeast models. The results showed that Vigna unguiculata subsp. sesquipedalis were the richest source of phytochemicals, whereas the population of V. mungo, Phaseolus vulgaris, V. angularis, and V. unguiculata subsp. sesquipedalis were richest in monomeric anthocyanin contents (MAC). Furthermore, the results clearly demonstrated the impact of the plant matrix effect on the preservation of a specific class of phytochemicals. In particular, after cooking and in vitro digestion, total flavonoid contents (TFC) in Glycine max extract was higher than in the uncooked sample. This study is the first report on the influence of cooking and in vitro gastrointestinal digestion on the inhibition capacity toward advanced glycation end products (AGEs). All samples showed a significant capacity to stimulate glucose uptake in yeast model, and V. angularis showed the highest capacity. Interestingly, the increase in glucose uptake after in vitro digestion was higher than in uncooked samples for both P. vulgaris and G. max samples. The current study is the first attempt to investigate at the effects of both processes not only on the natural bioactive compounds but also on antioxidant and anti-diabetic activities of Thailand's 10 most consumed beans that can be applied for agro-industrial and phytopharmaceutical sectors.

Characterization of Bioactive Phenolics and Antioxidant Capacity of Edible Bean Extracts of 50 Fabaceae Populations Grown in Thailand

Fabaceae is the third largest family containing great variation among populations. However, previous studies mainly focus on single species, and phytochemicals at population level have never been reported. This work aims to complete this knowledge with 50 populations from throughout Thailand by (1) determining total phenolic (TPC), flavonoid (TFC), and anthocyanin (TAC) contents; and (2) investigating in vitro and cellular antioxidant potentials. Phytochemicals of 50 populations from different localities are differed, illustrating high heterogeneity occurring in polyphenols accumulations. Vigna unguiculata subsp. sesquipedalis populations showed low variability in TPC ranging from 628.3 to 717.3 mg/100 g DW gallic acid equivalent, whereas the high variability found in TFC and TAC range from 786.9 to 1536.1 mg/100 g DW quercetin equivalent, and 13.4 to 41.6 mg/100 g DW cyanidin equivalent. Red cultivar population #16 had the greatest TAC, but surprisingly the cream cultivars were relatively high in anthocyanins. HPLC quantification of genistein and daidzein showed great variations among populations. In vitro antioxidant results indicated that antioxidant capacity mediated by electron transfer. Cellular antioxidants ranged from 59.7% to 87.9% of ROS/RNS in yeast model. This study investigated at the population level contributing to better and frontier knowledge for nutraceutical/phytopharmaceutical sectors to seek potential raw plant material.

Green Extraction of Antioxidant Flavonoids from Pigeon Pea (Cajanus cajan (L.) Millsp.) Seeds and Its Antioxidant Potentials Using Ultrasound-Assisted Methodology

Pigeon pea is an important pea species in the Fabaceae family that has long been used for food, cosmetic, and other phytopharmaceutical applications. Its seed is reported as a rich source of antioxidants and anti-inflammatory flavonoids, especially isoflavones, i.e., cajanin, cajanol, daidzein, and genistein. In today’s era of green chemistry and green cosmetic development, the development and optimization of extraction techniques is increasing employed by the industrial sectors to provide environmentally friendly products for their customers. Surprisingly, there is no research report on improving the extraction of these isoflavonoids from pigeon pea seeds. In this present study, ultrasound-assisted extraction (USAE) methodology, which is a green extraction that provides a shorter extraction time and consumes less solvent, was optimized and compared with the conventional methods. The multivariate strategy, the Behnken–Box design (BBD) combined with response surface methodology, was employed to determine the best extraction conditions for this USAE utilizing ethanol as green solvent. Not only in vitro but also cellular antioxidant activities were evaluated using different assays and approaches. The results indicated that USAE provided a substantial gain of ca 70% in the (iso)flavonoids extracted and the biological antioxidant activities were preserved, compared to the conventional method. The best extraction conditions were 39.19 min with a frequency of 29.96 kHz and 63.81% (v/v) aqueous ethanol. Both the antioxidant and anti-aging potentials of the extract were obtained under optimal USAE at a cellular level using yeast as a model, resulting in lower levels of malondialdehyde. These results demonstrated that the extract can act as an effective activator of the cell longevity protein (SIR2/SIRT1) and cell membrane protector against oxidative stress. This finding supports the potential of pigeon pea seeds and USAE methodology to gain potential antioxidant and anti-aging (iso)flavonoids-rich sources for the cosmetic and phytopharmaceutical sectors.

Study of Phenolic Compounds and Antioxidant Capacity of Spanish Almonds

Phenolic compounds have an important influence on fruit and nut quality. Almonds have been shown to be rich sources of phenolic compounds, which possess health-beneficial properties. The objectives of the study were to optimize an extraction method to determine the total amount of polyphenols, flavonoids and proanthocyanidins as well as the antioxidant capacity. In addition, the same extract was used for the identification and quantification of flavonoids by HPLC. The study was conducted on 11 Spanish almond genotypes. The results highlight the differences in the content of antioxidants, which add value to the quality of the fruit. It has been shown that genotype may strongly influence antioxidant capacity and total phenolic compounds. In this work, the almonds with higher results were (Belona, Guara and Vialfas) varieties.

Characterization of Sweet Almond Oil Content of Four European Cultivars (Ferragnes, Ferraduel, Fournat, and Marcona) Recently Introduced in Morocco

This study concerns the characterization of oil content and quality indices for almond cultivars (Marcona (Mr), Fournat (Fn), Ferragnes (Fg), and Ferraduel (Fd)) recently introduced into marginal agricultural areas in eastern Morocco. These verities are known for their rusticity and late flowering stage. The analyzed almond oils showed low acidity and peroxide values ranging, respectively, from 0.32 to 0.36% and 1.88 to 3.18 meq O₂/kg. Fatty acid (FA) profile revealed a predominance of the unsaturated FA represented essentially by the oleic (56.64-64.03%) and linoleic FA (24.57-29.80%). Triacylglycerol (TAG) analysis allowed the determination of eleven species with a remarkable dominance of trioleylglycerol (OOO: 30%) and dioleyllinoleoylglcerol (OOL: 27.25%). Regarding the minor compounds, the results showed that the total phenol content ranges between 85.33 and 141.66 mg/kg. Concerning the tocopherol content, the studied oils showed richness in these secondary metabolites (408.99-491.77 mg/kg) with a dominance of α-tocopherol. In comparison to their homologues in the Mediterranean area, the evaluated almond oils demonstrated a slight superiority in terms of quality, in particular, to those produced in Spain.

Revalorization of Almond By-Products for the Design of Novel Functional Foods: An Updated Review

The search for waste minimization and the valorization of by-products are key to good management and improved sustainability in the food industry. The great production of almonds, based on their high nutritional value as food, especially almond kernels, generates tons of waste yearly. The remaining parts (skin, shell, hulls, etc.) are still little explored, even though they have been used as fuel by burning or as livestock feed. The interest in these by-products has been increasing, as they possess beneficial properties, caused by the presence of different bioactive compounds, and can be used as promising sources of new ingredients for the food, cosmetic and pharmaceutical industry. Additionally, the use of almond by-products is being increasingly applied for the fortification of already-existing food products, but there are some limitations, including the presence of allergens and mycotoxins that harden their applicability. This review focuses on the extraction technologies applied to the valorization of almond by-products for the development of new value-added products that would contribute to the reduction of environmental impact and an improvement in the sustainability and competitiveness of the almond industry.

Almond By-Products: Valorization for Sustainability and Competitiveness of the Industry

The search for waste minimization and the valorization of by-products are key practices for good management and improved sustainability in the food industry. The production of almonds generates a large amount of waste, most of which is not used. Until now, almonds have been used for their high nutritional value as food, especially almond meat. The other remaining parts (skin, shell, hulls, etc.) are still little explored, even though they have been used as fuel by burning or as livestock feed. However, interest in these by-products has been increasing as they possess beneficial properties (caused mainly by polyphenols and unsaturated fatty acids) and can be used as new ingredients for the food, cosmetic, and pharmaceutical industries. Therefore, it is important to explore almond’s valorization of by-products for the development of new added-value products that would contribute to the reduction of environmental impact and an improvement in the sustainability and competitiveness of the almond industry.

Optimization of Microwave and Ultrasound Extraction Methods of Açai Berries in Terms of Highest Content of Phenolic Compounds and Antioxidant Activity

Rapid technological progress focuses on lowering costs, labor and time. Thus, in order to minimize the expenses of bioactive compound production, great effort is undertaken to optimize the extraction of these compounds. Green extraction is popular and relatively inexpensive. However, the same extraction method does not always work for all types of matrixes due to the biological diversity of the tissue. Therefore, the purpose of this study was to identify the optimal green extraction method of açai berries (ultrasound or microwaves) able to isolate extracts containing the highest possible number of phenolic compounds with the highest antioxidant activity. The results show that the highest content of total phenolic compounds in the extracts was obtained after the application of a temperature of 45 °C, using ultrasound for 25 min and 45 min, microwaves for 3.16 min and a water bath for 25 min. Ultrasound turned out to be the most effective method of flavonoid extraction. In turn, the highest anthocyanin content was obtained for microwave extraction. Additionally, the application of microwaves for 4.33 min (45 °C) guaranteed the highest ferric-reducing antioxidant activity (FRAP) among the extracts. The results show that the use of microwaves shortens the açai extraction time and ensures both a high content of total phenolic compounds and strong antioxidant activity in the extract.

The evaluation of extraction of some nut oils using screw pressing

Today's consumers prefer low-sugar, low-calorie, natural, and so-called safe products. These trends are also reflected in nuts products and groceries. Globally, the European Union is the largest importing market of edible nuts. Considering the increasing demand for new sources of food, the importance becomes the efficiency of production. This study evaluates the influence of rotation speed in the extraction of almond nut, walnut, hazelnut, cashew nut, and peanut oils using screw pressing. In tested samples, the oil content was on average between 69.14 ±0.79% (walnut) and 46.7 ±1.45% (peanut). From the pressing of oils, it is seen that the oil yield decreased when pressing speed increased (from 30 rpm to 90 rpm, for example in walnut from 0.36 kg to 0.16 kg.h-1) and that the oil sediment yield increased when speed increased (for example in hazelnut nut from 8.51% to 17.37%). The highest amount of oil yields had hazelnut with 3.03 ±0.05 kg.h-1, then walnut with 2.05 ±0.02 kg.h-1, almond nut with 2.34 ±0.05 kg.h-1, peanut with 2.15 ±0.01 kg.h-1, and finally cashew nut with 2.07 ±0.03 kg.h-1.

Extraction of Flavonoids From Natural Sources Using Modern Techniques

Flavonoids are one of the main groups of polyphenols found in natural products. Traditional flavonoid extraction techniques are being replaced by advanced techniques to reduce energy and solvent consumption, increase efficiency and selectivity, to meet increased market demand and environmental regulations. Advanced technologies, such as microwaves, ultrasound, pressurized liquids, supercritical fluids, and electric fields, are alternatives currently being used. These modern techniques are generally faster, more environmentally friendly, and with higher automation levels compared to conventional extraction techniques. This review will discuss the different methods available for flavonoid extraction from natural sources and the main parameters involved (temperature, solvent, sample quantity, extraction time, among others). Recent trends and their industrial importance are also discussed in detail, providing insight into their potential. Thus, this paper seeks to review the innovations of compound extraction techniques, presenting in each of them their advantages and disadvantages, trying to offer a broader scope in the understanding of flavonoid extraction from different plant matrices.

Enrichment in Antioxidant Flavonoids of Stamen Extracts from Nymphaea lotus L. Using Ultrasonic-Assisted Extraction and Macroporous Resin Adsorption

Nymphaea lotus L. is the medicinal plant that has long been used for food, cosmetics and traditional medicines in Africa and Asia since ancient times. Its flavonoids and other interesting phytochemical compounds from rhizome, leaf and the whole flowers have been reported in the previous published research. However, stamens, which are essential for reproductive functions, may also represent new alternative sources of potential antioxidant flavonoids, as investigated in this study. The innovative green chemistry methods, i.e., ultrasound-assisted extraction (UAE) as well as a macroporous resin (MPR) purification procedure, were employed in this current research. Using a full factorial design coupled to three-dimensional (3D) surface plot methodology, the influence of three variables, namely aqEtOH concentration (ranging from 50 to 100% (v/v), US frequency (ranging from 0 (no US applied) to 45 kHz), and the extraction duration (ranging from 20 to 60 min), were evaluated. Five MPRs with different surface areas, average pore diameters, matrix types and polarities were also investigated for the purification of total flavonoids. The optimal UAE condition is 90% (v/v) aqEtOH with 34.65 khz ultrasonic frequency and 46 min of extraction duration. Compared with the conventional heat reflux extraction (HRE) method, a significant 1.35-fold increase in total flavonoids content was obtained using optimized UAE conditions (169.64 for HRE vs. 235.45 mg/g dry weight for UAE), causing a 2.80-fold increase when this UAE associated with MPR purification (475.42 mg/g dry weight). In vitro cell free antioxidant activity of N. lotus stamen extracts and in cellulo antioxidant investigation using yeast model showed the same trend, indicating that the best antioxidant flavonoid can be found in UAE coupled with MPR purification. Moreover, in the yeast model, the expression of key antioxidant genes such as SIR2 and SOD2 were expressed at the highest level in yeast cells treated with the extract from UAE together with MPR purification. Consequently, it can be seen that the UAE combined with MPR purification can help enhance the flavonoid antioxidant potential of the stamens extract from this medicinal species.

Almond Skin Extracts and Chlorogenic Acid Delay Chronological Aging and Enhanced Oxidative Stress Response in Yeast

Almond (Prunus dulcis (Mill.) D.A.Webb) is one of the largest nut crops in the world. Recently, phenolic compounds, mostly stored in almond skin, have been associated with much of the health-promoting behavior associated with their intake. The almond skin enriched fraction obtained from cold-pressed oil residues of the endemic Moroccan Beldi ecotypes is particularly rich in chlorogenic acid. In this study, both almond skin extract (AE) and chlorogenic acid (CHL) supplements, similar to traditional positive control resveratrol, significantly increased the chronological life-span of yeast compared to the untreated group. Our results showed that AE and CHL significantly reduced the production of reactive oxygen and nitrogen species (ROS/RNS), most likely due to their ability to maintain mitochondrial function during aging, as indicated by the maintenance of normal mitochondrial membrane potential in treated groups. This may be associated with the observed activation of the anti-oxidative stress response in treated yeast, which results in activation at both gene expression and enzymatic activity levels for SOD2 and SIR2, the latter being an upstream inducer of SOD2 expression. Interestingly, the differential gene expression induction of mitochondrial SOD2 gene at the expense of the cytosolic SOD1 gene confirms the key role of mitochondrial function in this regulation. Furthermore, AE and CHL have contributed to the survival of yeast under UV-C-induced oxidative stress, by reducing the development of ROS/RNS, resulting in a significant reduction in cellular oxidative damage, as evidenced by decreased membrane lipid peroxidation, protein carbonyl content and 8-oxo-guanine formation in DNA. Together, these results demonstrate the interest of AE and CHL as new regulators in the chronological life-span and control of the oxidative stress response of yeast.