Optimization of process variables of probe ultrasonic‐assisted extraction of phenolic compounds from the peel of Punica granatum Var. Bhagwa and it's chemical and bioactivity characterization

Optimizing extraction methods by a comprehensive experimental approach and characterizing polyphenol compositions of Ecklonia radiata

Brown seaweed Ecklonia radiata harbors valuable polyphenols, notably phlorotannins, prized for their health benefits. This study optimized phlorotannin extraction via conventional solvent extraction and ultrasound-assisted extraction methods, utilizing variable concentrations of ethanol. Employing fractional factorial designs, key variables were identified. Steepest ascent/descent method and central composite rotatable designs refined optimal conditions, enhancing phlorotannin and polyphenol yields, and antioxidant capacities. Under optimized conditions, phlorotannin contents reached 2.366 ± 0.01 and 2.596 ± 0.04 PGE mg/g, total polyphenol contents peaked at 10.223 ± 0.03 and 10.836 ± 0.02 GAE mg/g. Robust antioxidant activity was observed: DPPH and OH radical scavenging capacities measured 27.891 ± 0.06 and 17.441 ± 0.08 TE mg/g, and 37.498 ± 1.12 and 49.391 ± 0.82 TE mg/g, respectively. Reducing power capacities surged to 9.016 ± 0.02 and 28.110 ± 0.10 TE mg/g. Liquid chromatography-mass spectrometry (LC-MS) and high-performance liquid chromatography (HPLC) analyses revealed enriched antioxidant compounds. Variations in polyphenol profiles were noted, potentially influencing antioxidant capacity nuances. This study illuminated the potential of E. radiata potential as a polyphenol source and offers optimized extraction methods poised to benefit various industries.

Anthocyanins from pomegranate peel (Punica granatum), chili pepper fruit (Capsicum annuum), and bougainvillea flowers (Bougainvillea spectabilis) with multiple biofunctions: Antibacterial, antioxidant, and anticancer

Background

Natural colorants, including natural pigments, e.g., anthocyanins, carotenoids, and chlorophylls, in novel and attractive food matrixes have become a popular trend. They impart favorite colors to food products and provide significant therapeutic effects. This study is aimed at extracting and identifying some natural pigments from different plant sources and evaluating their ability as antibacterial, antioxidant, and anticancer activities.

Methods

The anthocyanin-rich extract (ARE) is derived from three natural plant sources: pomegranate peel (Punica granatum), chili pepper fruit (Capsicum annuum), and Bougainvillea flowers. Bougainvillea spectabilis are analyzed for biochemical composition, as well as antioxidant, antibacterial, and anticancer activity, HPLC, DPPH, FRAP, disc diffusion assay, MIC, MTT, VEGFR-2, and caspase-9 assays.

Results

All three extracts had varying total phenolic contents, ranging from 14 to 466 mg GAE/g extract, where Punica granatum was the highest (466 mg GAE/g extract), followed by Bougainvillea spectabilis (180 mg GAE/g extract), and then Capsicum annuum (14 mg GAE/g extract). The antioxidant activity rose steadily with raising concentration. The ARE of pomegranate peels recorded highest value, followed by Bougainvillea flowers and chili pepper fruit. The MTT assay revealed an inhibitory action of the tested extracts on the proliferation of HCT-116, MCF-7, and HepG2 in a concentration-based manner. Gene expression of caspase-9 transcripts was considerably multiplied by the application of ARE of pomegranate peels. All the tested extracts inhibited VEGFR-2, and the inhibition (%) expanded gradually with increasing concentrations, achieving the highest value (80 %) at 10 μg/mL. The ARE of pomegranate peels scored highest antibacterial activity, followed by ARE of chili pepper fruit and Bougainvillea flowers. The inhibition zone diameter escalated gradually with rising concentrations of the tested samples.

Conclusion

The AREs of the three studied plant sources can be used as multifunctional products with antioxidant, anticancer, and antibacterial activities that are natural, safe, and cheap.

Influence of intensity ultrasound on rheological properties and bioactive compounds of araticum (Annona crassiflora) juice

The use of extracts rich in bioactive compounds is becoming increasingly common in the food, cosmetics, and pharmaceutical industries for the production of functional products. Araticum is a potential fruit to be analyzed due to its content of phenolic compounds, carotenoids and vitamins, with antioxidant properties. Therefore, this study aimed to investigate the effect of ultrasound on total phenolic compounds, total carotenoids, ascorbic acid, color, turbidity and rheology in araticum juice. Response surface methodology based on a central composite design was applied. Araticum juice was subjected to sonication at amplitude levels ranging from 20 to 100 % of the total power (400 W) at a constant frequency of 20 kHz for different durations (2 to 10 min). Morphological analysis was conducted to observe microscopic particles, and viscosity and suitability to rheological models (Newtonian, Power Law, and Herschel-Bulkley) were assessed. The ultrasonic probe extraction method was compared to the control juice. According to the responses, using the desirability function, the optimal conditions for extraction were determined to be low power (low amplitude) applied in a short period of time or low power applied in a prolonged time. These conditions allowed an ultrasonic probe to act on releasing bioactive compounds without degrading them. All three rheological models were suitable, with the Power Law model being the most appropriate, exhibiting non-Newtonian pseudoplastic behavior.

Effects of natural waste on in vitro oxidative DNA damage

In this study, the effects of natural waste products such as extracts from C. coggygria leaves and Punica granatum L. peels were investigated against oxidative DNA damage induced by Fenton reaction. 8-OH-2'dG as a general marker of DNA damage on thymus DNA, and the bioactive compounds of extracts were measured by LC-MS/MS. Our results had shown that ethanol extracts of C. coggygria leaf and Punica granatum L. peel had a protective effect on oxidative damaged DNA. It was determined that the bioactive compounds of C. coggygria leaves (gallic acid, protocatechuic acid, myricetin, syringic acid and ethyl gallate as a major compounds) and Punica granatum L. peel (ellagic acid, abscisic acid, ethyl gallate, phlorizin, gallic acid, myricetin as major compounds) may have an important role in the protective effect against oxidative DNA damage. Therefore, Cotinus coggygria leaves and Punica granatum L. peel may have potential use in medicine or cosmetic fields.

Application of ultrasound technology for the effective management of waste from fruit and vegetable

Food waste presents a continuous challenge for the food industry, leading to environmental pollution and economic issues. A substantial amount of waste, including by-products from fruits and vegetables, non-edible food items, and other waste materials, is produced throughout the food supply chain, from production to consumption. Recycling and valorizing waste from perishable goods is emerging as a key multidisciplinary approach within the circular bio-economy framework. This waste, rich in raw by-products, can be repurposed as a natural source of ingredients. Researchers increasingly focus on biomass valorization to extract and use components that add significant value. Traditional methods for extracting these bio-compounds typically require the use of solvents and are time-consuming, underscoring the need for innovative techniques like ultrasound (US) extraction. Wastes from the processing of fruits and vegetables in the food industry can be used to develop functional foods and edible coatings, offering protection against various environmental factors. This comprehensive review paper discusses the valorization of waste from perishable items like fruits and vegetables using US technology, not only to extract valuable components from waste but also to treat wastewater in the beverage industry. It also covers the application of biomolecules recovered from this process in the development of functional foods and packaging.

Ultrasonication/dynamic maceration-assisted extraction method as a novel combined approach for recovery of phenolic compounds from pomegranate peel

According to recent studies, pomegranate peel (PP) has the potential to be inverted from environmental pollutant waste to wealth due to possessing valuable phenolic compounds at a higher amount compared to edible parts. So far, different types of biological activities such as antimutagenic, antiproliferative, anti-inflammatory, and chemo-preventive properties were stated for pomegranate peel extract (PPE) according to chemical composition. In the present research, the probable intensifying effects of two extraction methods and optimum conditions for novel combined method of ultrasonication and dynamic maceration-assisted extraction of PPE using response surface methodology (RSM) were determined. A Box-Behnken Design (BBD) was employed to optimize three extraction variables, including sonication time (X1), sonication temperature (X2), and stirring speed (X3) for the achievement of high extraction yield of the phenolic compounds and antioxidant activity. The optimized conditions to obtain maximum extraction efficiency were determined as X1 = 70 min, X2 = 61.8°C, and X3 = 1000 rpm. The experimental values were in line with the values anticipated by RSM models, which indicates the appropriateness of the applied quadratic model and the accomplishment of RSM in optimizing the extraction conditions. The results suggest that the extraction of PPE by mix of ultrasonication as a modern method and dynamic maceration as a conventional method could improve its bioactive extractability and the obtained values were higher than any of the methods used. In other words, these two methods together have intensifying effects in increasing extraction efficiency which could further be utilized in food and agricultural industry.

Pomegranate Peel Phytochemistry, Pharmacological Properties, Methods of Extraction, and Its Application: A Comprehensive Review

Pomegranate peel, derived from the processing of Punica granatum L. (pomegranate), has traditionally been considered agricultural waste. However, recent studies have revealed its potential as a rich source of bioactive compounds with diverse pharmacological effects. Pomegranate peel is a rich reservoir of antioxidants, polyphenols, dietary fiber, and vitamins, which contribute to its remarkable bioactivity. Studies have demonstrated the anti-inflammatory, cardioprotective, wound healing, anticancer, and antimicrobial properties of pomegranate peel owing to the presence of phytochemicals, such as gallic acid, ellagic acid, and punicalagin. The extraction of bioactive compounds from pomegranate peel requires a careful selection of techniques to maximize the yield and quality. Green extraction methods, including pressurized liquid extraction (PLE), ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and enzyme-assisted extraction (EAE), offer efficient and sustainable alternatives to traditional methods. Furthermore, pomegranate peel has been utilized in the food industry, where it can significantly enhance the nutritional value, organoleptic characteristics, and shelf life of food products. Pomegranate peel has the potential to be used to develop innovative functional foods, nutraceuticals, and other value-added products, providing new opportunities for the pharmaceutical, cosmetic, and food industries.

Butylene Glycol Used as a Sustainable Solvent for Extracting Bioactive Compounds from Camellia sinensis Flowers with Ultrasound-Assisted Extraction

The research aims to assess the yield of bioactive compounds and their antioxidant activities obtained from tea flowers using an ultrasound-assisted extraction method with butylene glycol (BG-UAE) through Box-Behnken design. It investigates the bioactive compounds including the total phenolic content (TPC), total flavonoid content (TFC), and total tannin content (TTC) and analyzes their antioxidant activities, bioactive compound composition by liquid chromatography triple quadrupole tandem mass spectrometry, and their cellular activities via UAE and maceration using BG or ethanol as the solvent. Under optimal conditions, the values of the TPC, TFC, TTC, 1,1-diphenyl-2-picrylhydrazil radical scavenging assay, 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid radical scavenging assay, and ferric reducing antioxidant power assay (FRAP) of the BG-UAE extract were 54.00 ± 1.19 mg GAE/g sample, 291.47 ± 3.34 mg QE/g sample, 65.37 ± 1.78 mg TAE/g sample, 106.45 ± 1.21 mg TEAC/g sample, 163.58 ± 2.76 mg TEAC/g sample, and 121.31 ± 4.75 mg FeSO₄/g sample, respectively. Except for FRAP, BG-UAE exhibited the highest values in all parameters compared to the other extraction methods. Catechins and caffeine were predominantly detected in tea flower extracts through UAE with BG and ethanol (EtOH-UAE). BG-UAE exhibited greater cell viability and cellular antioxidant activity than EtOH-UAE. The researcher expects that this research will contribute to the emergence of a green extraction technique that will offer larger functional components with economic and environmental benefits and minimal chemicals and energy use.

Optimization of Ultrasound- and Microwave-Assisted Extraction for the Determination of Phenolic Compounds in Peach Byproducts Using Experimental Design and Liquid Chromatography-Tandem Mass Spectrometry

The conversion of plant byproducts, which are phenolic-rich substrates, to valuable co-products by implementing non-conventional extraction techniques is the need of the hour. In the current study, ultrasound- (UAE) and microwave-assisted extraction (MAE) were applied for the recovery of polyphenols from peach byproducts. Two-level screening and Box-Behnken design were adopted to optimize extraction efficiency in terms of total phenolic content (TPC). Methanol:water 4:1% v/v was the extraction solvent. The optimal conditions of UAE were 15 min, 8 s ON-5 s OFF, and 35 mL g^-1, while MAE was maximized at 20 min, 58 °C, and 16 mL g^-1. Regarding the extracts' TPC and antioxidant activity, MAE emerged as the method of choice, whilst their antiradical activity was similar in both techniques. Furthermore, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine chlorogenic acid and naringenin in byproducts' extracts. 4-Chloro-4'-hydroxybenzophenone is proposed as a new internal standard in LC-MS/MS analysis in foods and byproducts. Chlorogenic acid was extracted in higher yields when UAE was used, while MAE favored the extraction of the flavonoid compound, naringenin. To conclude, non-conventional extraction could be considered as an efficient and fast alternative for the recovery of bioactive compounds from plant matrices.

Optimization of ultrasound-assisted extraction of bioactive compounds from coffee pulp using propylene glycol as a solvent and their antioxidant activities

In the cosmetic and pharmaceutical industries, it has been increasingly popular to use alternative solvents in the extraction of bioactive compounds from plants. Coffee pulp, a by-product of coffee production, contains different phenolic compounds with antioxidant properties. The effects of polyols, amplitude, extraction time, solvent concentration, and liquid-solid ratio on total phenolic content (TPC) using ultrasound-assisted extraction (UAE) were examined by single-factor studies. Three main factors that impact TPC were selected to optimize the extraction conditions for total phenolic content (TPC), total flavonoid content (TFC), total tannin content (TTC), and their antioxidant activities using the Box-Behnken design. Different extraction methods were compared, the bioactive compounds were identified and quantified by liquid chromatography triple quadrupole mass spectrometer (LC-QQQ), and the cytotoxicity and cellular antioxidant activities of the extract were studied. According to the response model, the optimal conditions for the extraction of antioxidants from coffee pulp were as follows: extraction time of 7.65 min, liquid-solid ratio of 22.22 mL/g, and solvent concentration of 46.71 %. Under optimized conditions, the values of TPC, TFC, TTC, 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging assay, 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging assay, and Ferric reducing antioxidant power assay (FRAP) were 9.29 ± 0.02 mg GAE/g sample, 58.82 ± 1.38 mg QE/g sample, 8.69 ± 0.25 mg TAE/g sample, 7.56 ± 0.27 mg TEAC/g sample, 13.59 ± 0.25 mg TEAC/g sample, and 10.90 ± 0.24 mg FeSO₄/g sample, respectively. Compared with other extraction conditions, UAE with propylene glycol extract (PG-UAE) was significantlyhigher in TPC, TFC, TTC, DPPH, ABTS, and FRAP response values than UAE with ethanol (EtOH-UAE), maceration with propylene glycol (PG-maceration), and maceration with ethanol (EtOH -maceration) (p < 0.05). Major bioactive compounds detected by LC-QQQ included chlorogenic acid, caffeine, and trigonelline. At higher concentrations starting from 5 mg/ml, PG-UAE extract showed higher cell viability than EtOH-UAE in both cytotoxicity and cellular antioxidant assays. The researcher expects that this new extraction technique developed in this work could produce a higher yield of bioactive compounds with higher biological activity. Therefore, they can be used as active ingredients in cosmetics (anti-aging products) and pharmaceutical applications (food supplements, treatment for oxidative stress-related diseases) with minimal use of chemicals and energy.

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.

Antioxidant, Antimicrobial, and Metabolomic Characterization of Blanched Pomegranate Peel Extracts: Effect of Cultivar

Hot water blanching at 80 °C for 3 min can be used as a novel pre-treatment step in pomegranate peel to preserve the integrity of the phytochemical content within the peel extracts by lowering or inactivating enzymes such as polyphenol (PPO) oxidase and peroxidase (POD) that are responsible for the break-down of phytochemicals within the peel. The aim of this study was to investigate the effect of hot water blanching pre-treatment on yield, bioactive compounds, antioxidants, enzyme inactivation, and antibacterial activity of ‘Wonderful’, ‘Acco’, and ‘Herskawitz’ pomegranate peel extracts. We used a variety of spectrophotometric-based assays and liquid chromatography mass spectrometry (LC-MS)-based approach to characterize and quantify metabolites within the peel extracts. Blanching significantly (p < 0.05) reduced PPO activity in all peel extracts, with the highest PPO reduction in ‘Herskawitz’ peel extracts at 0.25 U/mL. Furthermore, higher antioxidant activity in ‘Herskawitz’ blanched peel extracts using 2,2-diphenyl-1-picryl hydrazyl (DPPH) antioxidant activity, ferric ion reducing antioxidant power (FRAP), and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity at 567.78 ± 9.47 µmol Trolox/g DM, 800.05 ± 1.60 µmol Trolox/g DM, and 915.27 ± 0.61 µmol Trolox/g DM, respectively, was noted. ‘Herskawitz’ blanched peel extracts were recorded with the lowest minimum inhibitory concentration (MIC) value of 80 µg/mL for Gram-positive Bacillus subtilis and Gram-negative Klebsiella pneumoniae bacteria strains. A total of 30 metabolites were present in ‘Acco’ and ‘Herskawitz’ peel extracts and were tentatively identified after LC-MS profiling. This study demonstrates that blanched peel extracts from ‘Herskawitz’ cultivar have great potential for commercial use in value-added products in the nutraceutical, cosmeceutical, and pharmacological industries.

Integrating diverse plant bioactive ingredients with cyclodextrins to fabricate functional films for food application: a critical review

The popularity of plant bioactive ingredients has become increasingly apparent in the food industry. However, these plant bioactive ingredients have many deficiencies, including low water solubility, poor stability, and unacceptable odor. Cyclodextrins (CDs), as cyclic molecules, have been extensively studied as superb vehicles of plant bioactive ingredients. These CD inclusion compounds could be added into various film matrices to fabricate bioactive food packaging materials. Therefore, in the present review, we summarized the extraction methods of plant bioactive ingredients, the addition of these CD inclusion compounds into thin-film materials, and their applications in food packaging. Furthermore, the release model and mechanism of active film materials based on various plant bioactive ingredients with CDs were highlighted. Finally, the current challenges and new opportunities based on these film materials have been discussed.

Optimization of calcium pectinate gel production from high methoxyl pectin

BACKGROUND

Calcium pectinate (CaP) gel is traditionally prepared by de-esterifying high methoxyl pectin (HMP) to low methoxyl pectin (LMP), followed by gelation with calcium. To save both time and cost in the production of CaP gel, an alternative method was developed by the addition of CaCl₂ to HMP at alkaline pH. To optimize the production, response surface methodology (RSM) was used to investigate the effects of temperature (30-50 °C), time (20-40 min) and pH (8-10) on yield, calcium content of the CaP gel and the degree of esterification (DE) of pectin following decalcification of CaP (DC-pectin).

RESULTS

The linear term for pH had a significant effect (P < 0.01) on all three responses, whereas interaction effects were not significant (P > 0.01), except on the calcium content (P < 0.01). The optimized process conditions (temperature, time and pH) to obtain maximum CaP-HMP gel yield (88.83%) were 50 °C, 40 min and pH 9.6, and for the highest calcium content (97.23 mg g^-1 ) they were 40 °C, 30 min and pH 9.7. DC-pectin was a typical LMP with DE varying from 26.92% to 50.33%. The DE of DC-pectin could be predicted by a model that proved significant (R²  = 0.9888).

CONCLUSION

The optimum conditions were established to produce CaP gels from HMP with high yield and calcium content. Also, LMP with predictable DE can be produced following a significant model. This study provides new insights into the production and application of CaP gel. © 2021 Society of Chemical Industry.

Influence of ultrasonic waves and conventional extraction methods on phenolic compound yield and phytochemical composition from Punica granatum L. peel

The objective of this work is to extract phenolic compounds from Punica granatum L. peel and to optimize the process variables. In this study, extraction was carried out using soxhlet, solvent and ultrasound-assisted extraction. Soxhlet extraction of phenolic compounds were reported as 87.31 mg GAE/g dW TPC, 70.30 mg RUE/g dW TFC and 98.68 mg CE/g dW TAC. Solvent extraction found 56.99 mg GAE/g dW, 42.93 mg RUE/g dW and 64.13 mg CE/g dW, while for ultrasonic-assisted extraction it was 77.23 mg GAE/g dW, 62.55 mg RUE/g dW and 91.40 mg CE/g dW of total phenolic content, total flavonoid content and total amount of anthocyanin content, respectively. The presence of phytochemicals was identified using GC-MS and it was found that the extracts contained high amount of trans-13-Octadecenoic acid which is a cancer preventive compound. Scanning electron microscope analysis was used to study the effect of ultrasound on the surface of the sample and understand the morphological changes.

Sonication, a Potential Technique for Extraction of Phytoconstituents: A Systematic Review

Traditional extraction techniques have lost their optimum performance because of rising consumer demand and novel technologies. In this regard, several techniques were developed by humans for the extraction of plant materials from various indigenous sources, which are no longer in use. Many of the techniques are not efficient enough to extract maximum plant material. By this time, evolution in extraction has led to development of various techniques including microfiltration, pulsed electric fields, high pressure, microwave assistance, enzyme assistance, supercritical fluid, subcritical fluid and ultrasonication. These innovations in food processing/extraction are known as “Green Food Processing”. These technologies were basically developed by focusing on three universal parameters: simplicity, energy efficiency and economy. These green technologies are practical in a number of different food sectors, mostly for preservation, inhibition of microorganisms, inactivation of enzymes and extraction of plant material. Like the others, ultrasonication could also be used for the said purposes. The primary objective of this review is to confine the potential use of ultrasonication for extraction of oils, pectin and phytochemicals by reviewing the literature systematically.

A Comprehensive Study of the Antibacterial Activity of Bioactive Juice and Extracts from Pomegranate (Punica granatum L.) Peels and Seeds

Due to the growing awareness of Punica granatum fruit’s health-promoting properties, the pomegranate is increasingly used for food purposes. This results in the formation of biological waste products such as peels. A biowaste circular bioeconomy strategy holds great prospective for a sustainable economy. Therefore, a sustainable and environmentally friendly way of disposing of waste (e.g., use of biowaste to obtain high-value components (e.g., punicalagins, enzymes)) is crucial for the protection of the environment and human health. In the presented study, the content of total phenols and proanthocyanidins in ten samples of Punica granatum fruit (juice, aqueous (H₂O) and ethanolic (EtOH) extracts of peels and seeds) was determined. Peel extracts were found to be the richest in the content of secondary metabolites and showed extremely high antioxidant potential (approximately 90% inhibition: DPPH radical scavenging activity). To the best of our knowledge, this is the first comparative study to determine the enzymatic activity of α-amylase, lipase, peroxidase, protease, and transglutaminase in different P. granatum samples. Furthermore, the antibacterial efficacy of all P. granatum samples was qualitatively determined against three strains of Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas fluorescens) and three strains of Gram-positive (Bacillus cereus, Staphylococcus aureus, and Streptococcus pyogenes) bacteria, susceptible to gaining antibiotic resistance. Moreover, the most promising peel extracts were quantified for antibacterial efficacy against tested bacteria at five different concentrations. All samples slowed down and inhibited the growth of all tested bacteria. MIC₉₀ values (2.7 or 0.3 mg/mL) were determined in 18 out of 24 experiments (four samples, six bacteria tested). There is no research in the reviewed literature that is current with such detailed and comprehensive determination of P. granatum peel extracts antibacterial activity. The results of the research showed great potential for the use of P. granatum in the field of antibacterial activity in biomedicine applications and in the cosmetic, food, and pharmaceutical industries.

Blanching Pre-Treatment Promotes High Yields, Bioactive Compounds, Antioxidants, Enzyme Inactivation and Antibacterial Activity of 'Wonderful' Pomegranate Peel Extracts at Three Different Harvest Maturities

'Wonderful' pomegranate (Punica granatum L.) peel contains a wide range of phytochemicals including vitamins, dietary fibre, phenolic compounds, and antioxidant properties. Yet, it is often used as animal feed or discarded in landfills, which is not the best eco-friendly way to utilize this phenolic-rich bioresource. Finding novel ways of utilizing pomegranate peel waste could prove a more profitable and eco-friendlier alternative that is far more beneficial to the economy. Adding a blanching pre-treatment step at optimal conditions prior to processing of pomegranate peel aids in the inactivation of quality changing enzymes such as polyphenol oxidase (PPO) and peroxidase (POD), which are accountable for the degradation reactions that cause breakdown of nutrients and phytochemicals. This study aimed to determine the effect of blanching at 80 °C for 3 min on the yield, polyphenol content, antioxidant properties, enzyme inactivation, and antibacterial activity of 'Wonderful' pomegranate peel ethanolic extracts from three different harvest maturities (unripe, ripe, and over ripe), including a comprehensive characterization and quantification using liquid chromatography-mass spectrometry (LC-MS). The blanched unripe peel extracts exhibited the highest total phenolic content, total tannin content, 2,2-diphenyl-1-picryl hydrazyl (DPPH) antioxidant activity, 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity and ferric ion reducing antioxidant power (FRAP) at 14.0 mg gallic acid equivalent (GAE)/g dry mass (DM), 1.0 mg GAE/g DM, 359.1 µmol Trolox/g DM, 912.2 µmol Trolox/g DM and 802.5 µmol Trolox/g DM, respectively. There was significant (p < 0.05) decrease in PPO and POD activity of all blanched pomegranate peel extracts. The blanched unripe peel extracts had the lowest PPO activity at 0.2 U/g fresh weight (FW), with a 70% PPO inactivation compared to ripe and over ripe harvest, whereas the highest POD inactivation was recorded at 67% in over ripe peel extracts. All blanched peel extracts, irrespective of harvest maturity, had minimum inhibitory concentration (MIC) values at 160 µg/mL against all four bacteria strains tested, which included two Gram-positive bacterial strains (Bacillus subtilis ATCC 6051 and Staphylococcus aureus ATCC 12600) and two Gram-negative bacteria (Escherichia coli 11775 and Klebsiella pneumonia ATCC 13883). A total of 25 metabolites including phenolic acids (4), organic acids (1), flavonoids (4), ellagitannins (13), and other polyphenols (3) in all three pomegranate peel samples were tentatively identified after LC-MS profiling. The blanched unripe peel extracts showed significantly higher punicalin α and β, β punicalagin, catechin, epicatechin content at 414 mg/g, and 678 mg/g, 151 mg/g, 229 mg/g, respectively, compared to peel extracts from other harvest maturities. This study provides supportive information for the commercial utilization of pomegranate fruit peel as source of value-added ingredients for the development of novel food, cosmetics, and pharmacological products.

Novel trends in extraction and optimization methods of bioactives recovery from pomegranate fruit biowastes: Valorization purposes for industrial applications

Pomegranate biowastes present potential economic value worldwide owing to their several health benefits mediated by a complex mixture of unique bioactives. The exploitation of these bioactives has motivated the exploration of eco-friendly, efficient, and cost-effective extraction techniques to maximize their recovery. The current review aims to provide updated technical information about bioactives extraction mechanisms from pomegranate wastes (seeds and peel), their advantages and disadvantages, and factors towards optimization. A comparative overview of the modern green extraction techniques viz., supercritical fluid extraction, ultrasound-assisted extraction, microwave-assisted extraction, pressurized liquid extraction, and eutectic solvent mixture as alternatives to conventional extraction methods for seeds and peel is presented. Approaches focused on biowastes modification for properties improvement are also discussed. Such comprehensive review shall provide the best valorization practices of pomegranate biowastes and its application in food and non-food areas focusing on original methods, innovation, protocols, and development to be considered for other fruit biowastes.

Effect of Solvent Extraction and Blanching Pre-Treatment on Phytochemical, Antioxidant Properties, Enzyme Inactivation and Antibacterial Activities of ‘Wonderful’ Pomegranate Peel Extracts

‘Wonderful’ pomegranate (Punica granatum L.) peel is rich in phytochemicals which are responsible for its strong antioxidant and antimicrobial activities, but it has low economic value as it is mainly discarded, causing an environmental waste management problem. To examine the best processing regime for pomegranate peel wastes, different solvents (ethanol, methanol and acetone) at various concentrations (50%, 70% and 100%) and blanching at 60, 80 and 100 °C for 1, 3 and 5 min, for each temperature, were tested. Ethanol at 70% (v/v) provided the highest extract yield, total phenolic and total tannin content at 29.46%, 10.61 ± 0.15, and 0.76 ± 0.02 mg GAE/g DM, respectively. Antioxidant activity using the 2,2 diphenyl-1-picryl hydrazyl assay (DPPH), ferric-reducing antioxidant power assay (FRAP) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid assay (ABTS) were reported at 243.97 ± 2.43, 478.04 ± 73.98 and 718.79 ± 2.42 µmol Trolox/g DM, respectively. A blanching temperature of 80 °C for 3 min led to the highest extract that had a total phenolic content of 12.22 ± 0.08 mg GAE/g DM and total tannin content of 1.06 ± 0.06 mg GAE/g DM. This extract also exhibited the best antioxidant activity for the DPPH, FRAP and ABTS assays. Two blanching temperatures, 80 or 100 °C, significantly reduced polyphenol oxidase and peroxidase activities (p < 0.05). Although blanched peel extracts showed a broad-spectrum activity against test bacteria, blanching at 80 °C for 3 or 5 min was most effective. Hot water blanching is thus a suitable environmentally friendly post-harvesting processing method for pomegranate peels that are intended for use as extracts in value-added products with good antioxidant and antibacterial effects.

Intensification of bio-actives extraction from pomegranate peel using pulsed ultrasound: Effect of factors, correlation, optimization and antioxidant bioactivities

Pomegranate peel (PP) is one of the interesting agri-food by-products because of its abundant bioactive phytochemicals. However, the bioactivity of valuable compounds is affected due to the extraction method used. A pulsed ultrasound-assisted extraction (PUAE) was carried out to intensify the extraction efficacy with reduced power and time. Influence of several process variables viz. peel solids/ solvent ratio, sonication power, duty cycle, and extraction time was studied using empirical quadratic models followed by multicriterial numerical optimization with respect to face-centered composite design. Power-duty cycle combination was found to be most significant (p < 0.05) for process intensification. The optimal process conditions of 2.17 g/100 mL S/S ratio at 116 W power with 80% duty cycle for 6 min resulted into 0.48 g/g yield, 177.54 mg GAE/g total phenolics content, 35.71 mg QE/g total flavonoids, 160.54 mg GAE/g antioxidant capacity, 21.65 mg cyn-3-glc/100 g anthocyanin content with 54.92 browning index in dry pomegranate peel. Significant Pearson correlation analysis was established in all responses with potent phenols and flavonoid relation with highest coefficient (r) 0.931. All response models were significantly validated with regression coefficient (R2) above 0.965. Remarkable antioxidant bioactivities were recorded for the resultant peel extract. Hence, it is strongly recommended that PUAE could be successfully applied for the intensification of the extraction process of bioactive from any peel and or plant systems with minimal process time and power consumption with a green label.

Nanotechnologies: An Innovative Tool to Release Natural Extracts with Antimicrobial Properties

Site-Specific release of active molecules with antimicrobial activity spurred the interest in the development of innovative polymeric nanocarriers. In the preparation of polymeric devices, nanotechnologies usually overcome the inconvenience frequently related to other synthetic strategies. High performing nanocarriers were synthesized using a wide range of starting polymer structures, with tailored features and great chemical versatility. Over the last decade, many antimicrobial substances originating from plants, herbs, and agro-food waste by-products were deeply investigated, significantly catching the interest of the scientific community. In this review, the most innovative strategies to synthesize nanodevices able to release antimicrobial natural extracts were discussed. In this regard, the properties and structure of the starting polymers, either synthetic or natural, as well as the antimicrobial activity of the biomolecules were deeply investigated, outlining the right combination able to inhibit pathogens in specific biological compartments.

Processing Factors Affecting the Phytochemical and Nutritional Properties of Pomegranate (Punica granatum L.) Peel Waste: A Review

Pomegranate peel has substantial amounts of phenolic compounds, such as hydrolysable tannins (punicalin, punicalagin, ellagic acid, and gallic acid), flavonoids (anthocyanins and catechins), and nutrients, which are responsible for its biological activity. However, during processing, the level of peel compounds can be significantly altered depending on the peel processing technique used, for example, ranging from 38.6 to 50.3 mg/g for punicalagins. This review focuses on the influence of postharvest processing factors on the pharmacological, phytochemical, and nutritional properties of pomegranate (Punica granatum L.) peel. Various peel drying strategies (sun drying, microwave drying, vacuum drying, and oven drying) and different extraction protocols (solvent, super-critical fluid, ultrasound-assisted, microwave-assisted, and pressurized liquid extractions) that are used to recover phytochemical compounds of the pomegranate peel are described. A total phenolic content of 40.8 mg gallic acid equivalent (GAE)/g DM was recorded when sun drying was used, but the recovery of the total phenolic content was higher at 264.3 mg TAE/g when pressurised liquid extraction was performed. However, pressurised liquid extraction is costly due to the high initial investment costs and the limited possibility of carrying out selective extractions of organic compounds from complex peel samples. The effects of these methods on the phytochemical profiles of pomegranate peel extracts are also influenced by the cultivar and conditions used, making it difficult to determine best practice. For example, oven drying at 60 °C resulted in higher levels of punicalin of 888.04 mg CE/kg DM compared to those obtained 40 °C of 768.11 mg CE/kg DM for the Wonderful cultivar. Processes that are easy to set up, cost-effective, and do not compromise the quality and safety aspects of the peel are, thus, more desirable. From the literature survey, we identified a lack of studies testing pretreatment protocols that may result in a lower loss of the valuable biological compounds of pomegranate peels to allow for full exploitation of their health-promoting properties in potentially new value-added products.

Chemical and physical attributes of fruit juice and peel of pomegranate genotypes grown in Florida, USA

The global demand for pomegranate has led to increasing research and improvement of cultivars that produce higher antioxidant compounds. The current study was carried out to evaluate the bioactive constituents and physical properties of fourteen pomegranate genotypes grown in the subtropical region of Florida. There were differences in aril color among genotypes. The highest total anthocyanin content was found in 'Ariana', 'Molla Nepes', and 'Parfianka' genotypes. Furthermore, total anthocyanin content in peel ranged from 2.14 to 10.86 mg/100 g dry weight. Total phenolic content in the pomegranate fruit juice differed significantly among genotypes, varying from 365.71 to 1167.40 mg/L. Moreover, total phenolic content in the fruit peel ranged from 1313.08 to 1700.07 mg/L. Total phenolic compounds and reducing power activity in peel tissues were greater than in pomegranate juice. Reducing power activity and titratable acidity were positively and significantly correlated with total anthocyanin content.

Novel Antioxidant Packaging Films Based on Poly(ε-Caprolactone) and Almond Skin Extract: Development and Effect on the Oxidative Stability of Fried Almonds

Antioxidant films based on poly(ε-caprolactone) (PCL) containing almond skin extract (ASE) were developed for food packaging applications. The effect of ASE incorporation on the morphological, structural, colour, mechanical, thermal, barrier and antioxidant properties of the prepared films were evaluated. The structural, tensile and thermal properties of the films were not altered due to ASE addition. Although no significant differences were observed for the oxygen permeability of samples, some increase in water absorption and water vapour permeability was observed for active films due to the hydrophilic character of ASE phenolic compounds, suggesting the suitability of this novel packaging for fatty foods conservation. ASE conferred antioxidant properties to PCL films as determined by the DPPH radical scavenging activity. The efficiency of the developed films was evaluated by the real packaging application of fried almonds at different ASE contents (0, 3, 6 wt.%) up to 56 days at 40 °C. The evolution of peroxide and p-anisidine values, hexanal content, fatty acid profile and characteristic spectroscopy bands showed that active films improved fried almonds stability. The results suggested the potential of PCL/ASE films as sustainable and antioxidant food packaging systems to offer protection against lipid oxidation in foods.