Optimization of Vacuum Microwave-Assisted Extraction of Pomegranate Fruits Peels by the Evaluation of Extracts' Phenolic Content and Antioxidant Activity

Optimization of ultrasonic-assisted extraction of total flavonoids from Oxalis corniculata by a hybrid response surface methodology-artificial neural network-genetic algorithm (RSM-ANN-GA) approach, coupled with an assessment of antioxidant activities

The objective of this research endeavor is to refine the ultrasonic-assisted extraction technique for total flavonoids from Oxalis corniculata (TFO), utilizing a synergistic approach combining response surface methodology (RSM) and artificial neural network integrated with genetic algorithm (RSM-ANN-GA). The optimized extraction parameters determined through RSM yielded a TFO concentration of 13.538 mg g-1 under the following conditions: an ethanol concentration of 61.95%, a liquid-solid ratio of 41.06 mL g-1, an ultrasonic power setting of 351.57 W, and an ultrasonic exposure duration of 58.95 minutes. Conversely, the RSM-ANN-GA approach identified an even more refined set of conditions, achieving a TFO concentration of 13.7844 mg g-1, with an ethanol concentration of 58.93%, a liquid-solid ratio of 41.16 mL g-1, an ultrasonic power of 350.22 W, and an ultrasonic exposure time of 58.18 minutes. These findings underscore the superior predictive accuracy and enhanced extraction efficiency offered by the RSM-ANN-GA model over the conventional RSM method. Furthermore, the study demonstrated that TFO possesses a potent antioxidant effect, as evidenced by its ability to scavenge DPPH, hydroxyl, and superoxide anion free radicals in vitro, highlighting its potential as a valuable source of natural antioxidants.

Assessing physicochemical characteristics of a shear-thinning polysaccharide mucilage extracted from marshmallow root (Althaea officinalis L.) by an ohmic heating system

Althaea officinalis L. root mucilage holds promise for food industries due to its functional properties. Despite various extraction techniques, ohmic systems remain underexplored for mucilage extraction. This study aimed to compare the efficacy of mucilage extraction using ohmic systems with maceration and investigate their physicochemical properties. The mucilage extraction was carried out utilizing maceration (M), ohmic-assisted extraction (OAE), and ohmic-assisted vacuum extraction (OAVE). Various parameters were evaluated, such as densities and specific energy consumption. The mucilage obtained by OAE had the highest yield (8.9 %). The highest solubility corresponded to the mucilage obtained by the OAE system (85.18 % at 65 °C). OAVE mucilage had 76.16 % swelling and 82.5 g water/g dry sample binding capacity, while OAE mucilage had 19.6 g water/g dry sample binding capacity. The OAVE mucilage oil absorption (12.3 g oil/g dry sample) was almost twice that of the OAE system. Rheological analysis characterized them as a pseudoplastic behavior. DSC thermogram of mucilage samples exhibited a singular endothermic peak (92.05 to 108.3 °C). FTIR analysis highlighted that the primary constituents of mucilage samples predominantly consisted of polysaccharides. This study concluded that ohmic-assisted extraction was the most efficient method for obtaining mucilage. Further research could explore the potential applications of this mucilage.

Exploring antioxidant potential of agricultural by-products: a systematic review

Background

Agricultural waste sourced from various activities that occur along the agricultural supply chain including post-harvest, processing, and consumption processes, can pose a threat to ecosystem balance and community welfare. Data shows that agricultural by-products have the potential to be utilized because they contain antioxidant compounds. This systematic review study aims to identify and assess the antioxidant activity of agricultural by-products through various extraction methods.

Methods

This systematic review collected literature in the last 10 years (2013-2023) from Google Scholar, Semantic, and Scopus-indexed articles with the help of Publish or Perish. Using the help of boolean operators (AND) and (OR) in searching using keywords. The steps applied adapt the PRISMA method (Preferred Reporting Items for Systematic Reviews and Meta-Analyses), including identification, screening, eligibility, and inclusion.

Results

Literature collection data shows that the dominant processing method used is the solvent extraction method to determine the antioxidant value of various agricultural waste by-products. Followed by microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) methods. A wide range of antioxidant activity values were found depending on the type of agricultural waste and processing technique. One potential utilization of agricultural wastes rich in antioxidant content is as additives in formulations in the cosmetic industry.

Conclusion

Agricultural waste by-products have high potential of antioxidant content, depending on the type of waste and extraction method. The dominant agricultural waste used is by-products from the fruit group. The utilization of agricultural waste that is rich in antioxidants has the potential to be utilized in the cosmetic industry.

Sustainable Extraction Protocols for the Recovery of Bioactive Compounds from By-Products of Pomegranate Fruit Processing

This study investigates sustainable extraction protocols for the recovery of bioactive compounds from by-products of various pomegranate (Punica granatum L.) cultivars, including Acco, Hicaz, Jolly Red, Parfianka, Valenciana, and Wonderful, generated during the industrial processing of the fruits. Advanced extraction technologies, including ultrasounds, microwaves, and hydrodynamic cavitation, have been compared to conventional extraction procedures and utilized to enhance extraction efficiency while also minimizing environmental impact. Water-based extraction methods have been utilized to promote the development of sustainable and eco-friendly processes. The comparison between conventional extractions and ultrasound-assisted extractions (UAEs) and microwave-assisted extractions (MAEs) demonstrated notable improvements in extraction yields, particularly for ellagitannins (punicalins, punicalagins, and ellagic acid) and total polyphenols, with increases ranging from about 45 to 200%. However, the increases directly comparing UAEs to MAEs ranged from about 4 to 6%. This indicates that while both UAEs and MAEs offer notable improvements over conventional extractions, the differences in extraction efficiency between the two advanced methods were relatively modest. These advancements were observed across various pomegranate cultivars, highlighting the versatility and effectiveness of these methods. Notably, hydrodynamic cavitation-based extractions (HC) emerged as particularly promising, consistently yielding the highest levels of bioactive compounds (ellagitannins and total polyphenols), especially when operated at higher frequencies. Compared to conventional extractions, HC exhibited substantial increases in extraction yields for Wonderful pomegranate by-products, surpassing the efficiency of both UAEs and MAEs (approximately 45 and 57% for UAE and MAE, respectively, versus about 80% for HC). Among these advanced techniques, HC has emerged as particularly promising, yielding the most favorable results and leading to significant improvements in the yield of bioactive compounds. When directly compared to UAEs and MAEs, HC increased extraction yields by over 20%. Furthermore, HC allowed for shorter extraction times. The Wonderful cultivar consistently exhibited the highest levels of ellagitannins and the highest total polyphenol content among all types of extraction procedures used, whether conventional or advanced. This highlights the great potential of the Wonderful cultivar in terms of bioactive compound extraction and underscores its significance in research and applications related to pomegranate processing and utilization. This study suggests that the implementation of these advanced technologies into extraction processes represents a significant advancement in the field, offering a promising avenue for the development of efficient and environmentally friendly extraction methods for obtaining valuable bioactive compounds from pomegranate processing by-products.

Advances in the novel and green-assisted techniques for extraction of bioactive compounds from millets: A comprehensive review

Millets are rich in nutritional and bioactive compounds, including polyphenols and flavonoids, and have the potential to combat malnutrition and various diseases. However, extracting these bioactive compounds can be challenging, as conventional methods are energy-intensive and can lead to thermal degradation. Green-assisted techniques have emerged as promising methods for sustainable and efficient extraction. This review explores recent trends in employing green-assisted techniques for extracting bioactive compounds from millets, and potential applications in the food and pharmaceutical industries. The objective is to evaluate and comprehend the parameters involved in different extraction methods, including energy efficiency, extraction yield, and the preservation of compound quality. The potential synergies achieved by integrating multiple extraction methods, and optimizing extraction efficiency for millet applications are also discussed. Among several, Ultrasound and Microwave-assisted extraction stand out for their rapidity, although there is a need for further research in the context of minor millets. Enzyme-assisted extraction, with its low energy input and ability to handle complex matrices, holds significant potential. Pulsed electric field-assisted extraction, despite being a non-thermal approach, requires further optimization for millet-specific applications, are few highlights. The review emphasizes the importance of considering specific compound characteristics, extraction efficiency, purity requirements, and operational costs when selecting an ideal technique. Ongoing research aims to optimize novel extraction processes for millets and their byproducts, offering promising applications in the development of millet-based nutraceutical food products. Therefore, the current study benefits researchers and industries to advance extraction research and develop efficient, sustainable, and scalable techniques to extract bioactive compounds from millets.

Sustainable utilization of apple pomace and its emerging potential for development of functional foods

Apple pomace, a byproduct of apple processing industry, possesses nutritional components which are of great interests for health aspects. Apple pomace is a good source of dietary fiber, minerals, carbohydrates, phenolic, and antioxidant compounds. These bioactive compounds can be extracted by different extraction techniques which have been comprehensively described in this review article. Furthermore, the incorporation of apple pomace as functional ingredients in different food products like bakery items, extrusion-based snacks, meat, dairy, and confectionary products to improve the commercial value and health benefits has been discussed briefly. This review article can be a helpful tool for industrialists, innovative researchers, and waste management authorities to manage the apple waste in an appropriate and sustainable way.

Enhancement of the bioavailability of phenolic compounds from fruit and vegetable waste by liposomal nanocarriers

Fruits and vegetables are one of the most consumed and processed commodities globally and comprise abundant phenolic compounds, one of the main nutraceuticals in the food industry. Comparably elevated rates of these compounds are found in waste (peel, seeds, leaf, stem, etc.) in the food processing industry. They are being investigated for their potential use in functional foods. However, phenolic compounds' low bioavailability limits their application, which can be approached by loading the phenolic compounds into an encapsulation system such as liposomal carriers. This review aims to elucidate the recent trend in extracting phenolic compounds from the waste stream and the means to load them in stable liposomes. Furthermore, the application of these liposomes with only natural extracts in food matrices is also presented. Many studies have indicated that liposomes can be a proper candidate for encapsulating and delivering phenolic compounds and as a means to increase their bioavailability.

Recent advances incombined Avant-garde technologies (thermal-thermal, non-thermal-non-thermal, and thermal-non-thermal matrix) to extract polyphenols from agro byproducts

Because food byproducts (waste) are rich in phytoconstituents, valorizing them is crucial for global food security. However, conventional extraction (CE), including decoction, maceration, Soxhlet, etc., for agro byproducts' polyphenol extraction are time-consuming and rely significantly on vast volumes of potentially aggressive solvents. Hence, Avantgarde extraction technologies, including non-thermal (high hydrostatic pressure (HHPE), pulsed-electric field (PEF), high voltage electrical discharges (HVED), etc.) and thermal extraction (supercritical fluid (SCF), subcritical water extraction (SWE), microwave-assisted extraction (MAE), etc.), as well as their thermal combinations (SCF-PLE, SCCO2-SWE, SCCO2-MAE, etc.), non-thermal combinations (HHPE + UAE, PEF + UAE, HVED + UAE, etc.) and combined thermalnon-thermal (MAE-UAE, etc.) are increasingly replacing CE. However, a review of combined Avant-garde extraction escalation technologies (non-thermal/thermal extraction matrix) for extracting polyphenols from agro-byproducts is limited. Hence, this manuscript reviewed Avant-garde extraction technologies (non-thermal/thermal extraction matrix) for extracting phenolics from agro-byproducts in the last 5 years. The key factors affecting polyphenols' extraction from the byproduct, the recent applications of Avant-garde technologies, and their principle were reviewed using databases from Web of Science and Lens.org. The results demonstrated that combined Avant-garde extraction escalation technologies increase extractability, resulting in polyphenols with higher extraction rates, fewer contaminants, and preservation of thermosensitive components. Therefore, combined Avant-garde extraction technologies should be explored over the next five years. Implementing an integrated process and the strategic sequencing of diverse Avant-garde extraction technologies are important. Thus, further investigation is required to explore the sequencing process and its potential impact on the extraction of phenolics from agro-byproducts.

Optimization studies on batch extraction of phenolic compounds from Azadirachta indica using genetic algorithm and machine learning techniques

Phenolic compounds play a crucial role as secondary metabolites due to their substantial biological activity and medicinal value. These compounds are present in various parts of plant species. This study focused on solid-liquid batch extraction to recover total phenolic compounds from Azadirachta indica leaves. The experimental design was based on the Taguchi L16 array, considering four independent factors: extraction time, temperature, particle size, and solid-to-solvent ratio. Among these factors, the particle size exerted the maximum influence. Particle size inversely affects the yield of total phenolic content (TPC), while temperature, time, and solid-to-liquid ratio have a direct impact. The process factors concerned were investigated both experimentally and through machine learning techniques. Support vector regression (SVR) and random forest method (RFM) algorithms were utilized for predicting TPC, while a genetic algorithm (GA) was employed to derive optimal process parameters. The GA predicts the optimal extraction factors, yielding the maximum TPC. During this study, these factors were the following: particle size of 0.15 mm, extraction time of 40 min, solid-to-liquid ratio of 1:25 g/mL, and a temperature of 55 °C, with a predicted value of 23.039 mg GAE/g of plant material. Notably, in this study, the SVR values of TPC yield closely matched the experimental values for the training and test data set when compared with the random forest method values.

Optimization of Microwave-assisted Extraction Technique for Flavonoids and Phenolics from the Leaves of Oroxylum indicum (L.) Kurtz Using Taguchi L9 Orthogonal Design

Background

An experimental design to obtain bioactive ingredients from Oroxylum indicum (L.) Kurtz was performed applying microwave-assisted extraction (MAE). Recently, tremendous research interest and benefits have been observed for extracting active constituents from plant materials using the microwave.

Objectives

This work aimed to develop an optimized, green, efficient, alternative procedure for extracting flavonoid and phenolic (total flavonoid content [TFC] and total phenolic content [TPC]) from leaves of Oroxylum indicum (L.) Kurtz.

Materials and Methods

A total of 1 g of the powdered sample was extracted using classical Soxhlet apparatus for 48 hr to ensure exhaustive extraction; simultaneously, maceration and ultrasound-assisted extraction were also carried out using 1 g of the plant sample for 12 hr and 60 min at 25˚C, respectively. The optimization of MAE was done using Taguchi L9 orthogonal design. The optimum operating conditions were microwave power (160 W), soaking time (4 min), irradiation time (4 min), and temperature (57˚C).

Results

The microwave method has shown 70% higher yield than other conventional techniques in a shorter time, along with increased TFC and TPC.

Conclusion

The TPC, TFC, and total antioxidant capacity (TAC) values are higher in the extract obtained by MAE extracts in comparison to other techniques. The extraction technique will be an ideal tool to safeguard the thermolabile plant constituents that will be more environmentally friendly.

From Pomegranate Byproducts Waste to Worth: A Review of Extraction Techniques and Potential Applications for Their Revalorization

The food industry is quite interested in the use of (techno)-functional bioactive compounds from byproducts to develop ‘clean label’ foods in a circular economy. The aim of this review is to evaluate the state of the knowledge and scientific evidence on the use of green extraction technologies (ultrasound-, microwave-, and enzymatic-assisted) of bioactive compounds from pomegranate peel byproducts, and their potential application via the supplementation/fortification of vegetal matrixes to improve their quality, functional properties, and safety. Most studies are mainly focused on ultrasound extraction, which has been widely developed compared to microwave or enzymatic extractions, which should be studied in depth, including their combinations. After extraction, pomegranate peel byproducts (in the form of powders, liquid extracts, and/or encapsulated, among others) have been incorporated into several food matrixes, as a good tool to preserve ‘clean label’ foods without altering their composition and improving their functional properties. Future studies must clearly evaluate the energy efficiency/consumption, the cost, and the environmental impact leading to the sustainable extraction of the key bio-compounds. Moreover, predictive models are needed to optimize the phytochemical extraction and to help in decision-making along the supply chain.

Preliminary Studies on Suppression of Important Plant Pathogens by Using Pomegranate and Avocado Residual Peel and Seed Extracts

Potential synergistic action of aqueous extracts of pomegranate peel (PP), avocado peel (AP), and avocado seed (AS) wastes isolated by microwave-assisted extraction were assessed in in vitro and in vivo assays as biocontrol agents against several plant pathogenic fungi. The study findings contribute to the utilization of a value-added industrial byproduct and provide significant value in advancing the development of new plant protecting compositions that benefit from the synergistic effects between two important plant species that contain several natural bioactive compounds. More specifically, the in vitro results proved that the use of 100%-pure (PP) extracted waste affected the mycelium growth of Penicillium expansum. Furthermore, mycelium growth of Aspergillus niger was decreased by 10.21% compared to control after 7 days of growth in medium agar containing 100% AP and extracted waste. Moreover, mycelium growth of Botrytis cinerea was affected by equal volume of avocado extraction wastes (50% peel and 50% seed) only at the first 3 days of the inoculation, while at the seventh day of the inoculation there was no effect on the mycelium growth. Equal volumes of the examined wastes showed decreased mycelium growth of Fusarium oxysporum f.sp. lycopersici by 6%, while Rhizoctonia solani mycelium growth was found to be the most sensitive in PP application. In addition, the in vivo assay shown that PP extract suppresses damage of tomato plants caused by R. solani followed by extracted wastes from AP. Based on the research findings, it can be argued that PP and AP extracts can be used as natural antifungals instead of dangerous synthetic antifungals to effectively treat phytopathogens that cause fruit and vegetable losses during cultivation.

Polyphenol Extracts From Germinated Mung Beans Can Improve Type 2 Diabetes in Mice by Regulating Intestinal Microflora and Inhibiting Inflammation

Studies have shown that inhibiting inflammation and regulating intestinal microflora imbalance is a significant factor in controlling the development of type 2 diabetes mellitus (T2DM). This experiment studied the protective effect of polyphenol extract from germinated mung beans on diabetic C57BL/6 mice.

Results

Fasting blood glucose (FBG) was decreased, glucose tolerance was increased, insulin resistance was decreased, serum lipid indexes in T2DM mice were improved, and the enzyme activities of alanine aminotransferase (ALT) and aspartate transaminase (AST) in serum were reduced. Meanwhile, the levels of interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and C-reactive protein (CRP) in serum were decreased, the concentration of interleukin 10 (IL-10) in serum was increased, inhibiting the inflammatory reaction induced by diabetes and repairing the morphology of mice liver tissue. At the same time, germinated mung bean polyphenol (GMP) can regulate the main intestinal flora, Firmicutes, Bacteroidetes, and Proteobacteria in diabetic mice and can also regulate species diversity and improve intestinal flora imbalance. Taken together, the experimental conclusion is a certain dose of polyphenol extract from germinated mung beans that can improve mouse T2DM by inhibiting inflammatory reaction and regulating intestinal microflora.

The bioactivity and applications of pomegranate peel extract: A review

Pomegranate peel (PP) is a by-product in the processing of pomegranate products, which is usually discarded as a waste. However, a large number of researches have shown that pomegranate peel extract (PPE) is rich in a variety of phenolic substances, among which ellagic acid (EA), as one of the main active components, has significant biological activities, such as anti-oxidation, anti-tumor, anti-inflammatory, neuroprotection, anti-viral, and anti-bacterial. We analyzed the mechanism of EA's biological activity, and discussed its application in the food industry, for instance, food preservation, food additives, and functional foods. Combined with the research status of PPE, we discussed the limitations and development potential of PPE, in order to provide theoretical reference and scientific basis for the development and utilization of pomegranate by-products. PRACTICAL APPLICATIONS: Pomegranate peel (PP), the inedible part of the fruit, is usually treated as waste. In recent years, researchers have been committed to exploring various bioactive ingredients in PP and exploring its potential benefits to human health, which has far-reaching significance. In this paper, the chemical constituents of polyphenols in PP were reviewed, mainly focusing on the biological activity and mechanism of ellagic acid (EA). We reviewed the applications and invention patents of pomegranate peel extract (PPE) in food field, including food preservation, food additive, and functional foods, providing reference for the recycling and reuse of PP.

Influence of the extraction method on the recovery of bioactive phenolic compounds from food industry by-products

Agro-foodindustries generate colossal amounts of non-edible waste and by-products, easily accessible as raw materials for up-cycling active phytochemicals. Phenolic compounds are particularly relevant in this field given their abundance in plant residues and the market interest of their functionalities (e.g. natural antioxidant activity) as part of nutraceutical, cosmetological and biomedical formulations. In "bench-to-bedside" achievements, sample extraction is essential because valorization benefits from matrix desorption and solubilization of targeted phytocompounds. Specifically, the composition and polarity of the extractant, the optimal sample particle size and sample:solvent ratio, as well as pH, pressure and temperature are strategic for the release and stability of mobilized species. On the other hand, current green chemistry environmental rules require extraction approaches that eliminate polluting consumables and reduce energy needs. Thus, the following pages provide an update on advanced technologies for the sustainable and efficient recovery of phenolics from plant matrices.

Antimicrobial Properties of Lyophilized Extracts of Olive Fruit, Pomegranate and Orange Peel Extracts against Foodborne Pathogenic and Spoilage Bacteria and Fungi In Vitro and in Food Matrices

Several novel antimicrobials with different concentrations of olive, pomegranate, and orange fruit pulp extracts were produced from agricultural byproducts and, after lyophilization, their antimicrobial activity and potential synergistic effects were evaluated in vitro and in food samples against foodborne pathogenic and spoilage bacteria and fungi. The Minimum Inhibitory of the tested bacteria was 7.5% or 10%, while fungi were inhibited at a concentration of 10% or above. The optical density of bacterial and yeast cultures was reduced to a different extent with all tested antimicrobial powders, compared to a control without antimicrobials, and mycelium growth of fungi was also restricted with extracts containing at least 90% olive extract. In food samples with inoculated pathogens and spoilage bacteria and fungi, the 100% olive extract was most inhibitory against E. coli, S. typhimurium, and L. monocytogenes in fresh burger and cheese spread samples (by 0.6 to 1.8 log cfu/g), except that S. typhimurium was better inhibited by a 90% olive and 10% pomegranate extract in burgers. The latter extract was also the most effective in controlling the growth of inoculated fungi (Aspergillus niger, Penicillium italicum, Rhodotorula mucilaginosa) in both yogurt and tomato juice samples, where it reduced fungal growth by 1–2.2 log cfu/g at the end of storage period. The results demonstrate that these novel encapsulated extracts could serve as natural antimicrobials of wide spectrum, in order to replace synthetic preservatives in foods and cosmetics.

Corn Silage Supplemented with Pomegranate (Punica granatum) and Avocado (Persea americana) Pulp and Seed Wastes for Improvement of Meat Characteristics in Poultry Production

In the present study, pomegranate peels, avocado peels, and seed vacuum microwave extraction solid by-products were supplemented in corn silage in order to investigate the effects on meat quality and growth rate in broiler chicken. There were 50 broilers, divided in two groups, treated with experimental or usual feed for 43 days (group A: 25 broilers fed with avocado and pomegranate by-products and group B: 25 broilers fed with corn-silage used as control). The results showed that broiler chickens fed with a diet supplemented with a mixture of pomegranate avocado by-products (group A) showed significant differences in chicken leg meat quality, significantly improving the level of proteins and fatty acids content in breast and leg meat, respectively. More specific ω3 and ω6 fatty acids content were three times higher than in group B. Moreover, a protective effect on the decomposition of polyunsaturated fatty acids, induced by free radicals and presented in chicken meat, is based on the evaluation of lipid peroxidation by measuring thiobarbituric acid reactive substances. Pomegranate peels, avocado peels, and seed by-products appeared to have a slight reduction on meat production, while it was found to improve the qualitative chicken meat characteristics. Regarding the production costs, it was calculated that the corn-silage supplementation, used in this study, lead to a 50% lower cost than the commercial corn-silage used for the breeding of broilers.

The In Vitro and In Vivo Synergistic Antimicrobial Activity Assessment of Vacuum Microwave Assisted Aqueous Extracts from Pomegranate and Avocado Fruit Peels and Avocado Seeds Based on a Mixtures Design Model

The present study aimed to assess the antimicrobial properties of encapsulated lyophilized powdered extracts of pomegranate peels (PP), avocado peels (AP) and avocado seeds (AS) in vitro and in vivo. Minimum Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) methods, optical density measurement, and well diffusion assay were used to determine antimicrobial activity against food borne bacteria (Gram− Escherichia coli, Salmonella typhimurium, Campylobacter jejuni, Pseudomonas putida), (Gram+ Staphylococcus aureus, Listeria monocytogenes, Clostridium perfringens, Lactobacillus plantarum), and fungi (Penicillium expansum and Aspergillus niger) based on a mixture design model. Additionally, the most effective powder was studied in vivo in yogurt, cream cheese, and minced meat burger. The samples that contained high polyphenol content also exhibited higher antioxidant, antimicrobial, and antifungal activity. From the results of the well diffusion, the MIC/MBC, and the cell optical density assays, the antimicrobial activity of the extracts was found to be correlated to the total phenolic content (TPC) of the samples and the type of the microorganism. The pomegranate peels extract presented the higher TPC and antioxidant activity and constitute the highest percentage in the most active antimicrobial mixture. The powders that were tested in vitro showed microbial type-dependent effects in each food model. The results presented here can be further studied in the large-scale industrial production of natural food preservatives.

Vacuum Microwave-Assisted Aqueous Extraction of Polyphenolic Compounds from Avocado (Persea Americana) Solid Waste

The extraction efficacy of avocado fruit peels (AP) and seeds (AS) with the use of vacuum microwave-assisted aqueous extraction (VMAAE) was optimized in this study, with regard to extract’s total phenolic content (TPC), maximum antioxidant activity and minimal operational cost. Temperature (79.64 and 78.11 °C for AP and 43.90 and 45.26 °C for AS), time (11.89 and 11.75 min for AP, 10.18 and 10.28 min for AS), ratio of water to raw material (16.45% and 10.02% for AP, 38.73% and 37.65% for AS) and microwave power (5708.04 and 5699.10 W for AP, 5549.08 and 4797.29 W for AS) were estimated statistically as the optimal conditions in order to achieve high rates of extracts with high TPC and antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH●) scavenging radical methods, respectively. VMAAE performed under these conditions resulted in received extracts with TPC (0.352 gallic acid equivalent-GAE/g fresh AP/min and 0.124 GAE/g fresh AS/min). Furthermore, it was calculated the DPPH● radical scavenging activity was equal to 100 mg/L expressed in L of 0.104 L/min for AP and 0.045 L/min for AS. The results of our study may give a promising solution to avocado processing companies for further utilization of their waste.

Optimization of the Vacuum Microwave Assisted Extraction of the Natural Polyphenols and Flavonoids from the Raw Solid Waste of the Pomegranate Juice Producing Industry at Industrial Scale

Pomegranate pomace (PP) is the solid waste produced in bulk by the pomegranate juice industry which is rich in polyphenols and flavonoids that can replace the hazardous chemical antioxidants/antimicrobials currently used in the agro-food and cosmetics sectors. In the present work, the vacuum microwave assisted extraction (VMAE) of natural antioxidants from raw pomegranate pomace was investigated and successfully optimized at an industrial scale. For the optimization of PP VMAE a novel, highly accurate response surface methodology (RSM) based on a comprehensive multi-point historical design was employed. The optimization showed that the maximum recovery of PP total polyphenols as well as total PP flavonoids were obtained at microwave power = 4961.07 W, water to pomace ratio = 29.9, extraction time = 119.53 min and microwave power = 4147.76 W, water to pomace ratio = 19.32, extraction time = 63.32 min respectively. Moreover, the optimal VMAE conditions on economic grounds were determined to be: microwave power = 2048.62 W, water to pomace ratio = 23.11, extraction time = 15.04 min and microwave power = 4008.62 W, water to pomace ratio = 18.08, extraction time = 15.29 min for PP total polyphenols and PP total flavonoids respectively. The main conclusion of this study is that the VMAE extraction can be successfully used at industrial scale to produce, in economic manner, high added value natural extracts from PP pomace.

Technologies and Extraction Methods of Polyphenolic Compounds Derived from Pomegranate (Punica granatum) Peels. A Mini Review

The interest in using plant by-product extracts as functional ingredients is continuously rising due to environmental and financial prospects. The development of new technologies has led to the achievement of aqueous extracts with high bioactivity that is preferable due to organic solvents nonuse. Recently, widely applied and emerging technologies, such as Simple Stirring, Pressure-Applied Extraction, Enzymatic Extraction, Ultrasound-Assisted Extraction, Pulsed Electric Fields, High Hydrostatic Pressure, Ohmic Heating, Microwave Assistant Extraction and the use of “green” solvents such as the deep eutectic solvents, have been investigated in order to contribute to the minimization of disadvantages on the extraction of bioactive compounds. This review is focused on bioactive compounds derived from pomegranate (Punica granatum) peels and highlighted the most attractive extraction methods. It is believed that these findings could be a useful tool for the pomegranate juices industry to apply an effective and economically viable extraction process, transforming a by-product to a high added value functional product.