Antimicrobial potential of pomegranate peel: a review

Application of Pomegranate by-Products in Muscle Foods: Oxidative Indices, Colour Stability, Shelf Life and Health Benefits

In recent years, considerable importance is given to the use of agrifood wastes as they contain several groups of substances that are useful for development of functional foods. As muscle foods are prone to lipid and protein oxidation and perishable in nature, the industry is in constant search of synthetic free additives that help in retarding the oxidation process, leading to the development of healthier and shelf stable products. The by-products or residues of pomegranate fruit (seeds, pomace, and peel) are reported to contain bioactive compounds, including phenolic and polyphenolic compounds, dietary fibre, complex polysaccharides, minerals, vitamins, etc. Such compounds extracted from the by-products of pomegranate can be used as functional ingredients or food additives to harness the antioxidant, antimicrobial potential, or as substitutes for fat, and protein in various muscle food products. Besides, these natural additives are reported to improve the quality, safety, and extend the shelf life of different types of food products, including meat and fish. Although studies on application of pomegranate by-products on various foods are available, their effect on the physicochemical, oxidative changes, microbial, colour stabilizing, sensory acceptability, and shelf life of muscle foods are not comprehensively discussed previously. In this review, we vividly discuss these issues, and highlight the benefits of pomegranate by-products and their phenolic composition on human health.

A Review of Plant Extracts and Plant-Derived Natural Compounds in the Prevention/Treatment of Neonatal Hypoxic-Ischemic Brain Injury

Neonatal hypoxic-ischemic (HI) brain injury is one of the major drawbacks of mortality and causes significant short/long-term neurological dysfunction in newborn infants worldwide. To date, due to multifunctional complex mechanisms of brain injury, there is no well-established effective strategy to completely provide neuroprotection. Although therapeutic hypothermia is the proven treatment for hypoxic-ischemic encephalopathy (HIE), it does not completely chang outcomes in severe forms of HIE. Therefore, there is a critical need for reviewing the effective therapeutic strategies to explore the protective agents and methods. In recent years, it is widely believed that there are neuroprotective possibilities of natural compounds extracted from plants against HIE. These natural agents with the anti-inflammatory, anti-oxidative, anti-apoptotic, and neurofunctional regulatory properties exhibit preventive or therapeutic effects against experimental neonatal HI brain damage. In this study, it was aimed to review the literature in scientific databases that investigate the neuroprotective effects of plant extracts/plant-derived compounds in experimental animal models of neonatal HI brain damage and their possible underlying molecular mechanisms of action.

Screening for Bioactive Compound Rich Pomegranate Peel Extracts and Their Antimicrobial Activities

In this work, seven different extracts from pomegranate (Punica granatum L., cv. Hicaz nar) peel were prepared by using different solvents (ethanol, methanol, either alone or in combination with acid, acetone and water). The phenolics (punicalagins and ellagic acid), organic acids (citric acid and malic acid) and sugars of pomegranate peel extracts were determined. The highest amounts of punicalagins and ellagic acid were detected by ethanol-acid extract as 13.86% and 17.19% (w/v) respectively, whereas the lowest levels were obtained with acetone and water extracts. Moreover, the methanol-acid (3.19% malic acid) and ethanol-acid (1.13% citric acid) extracts contained the highest levels of organic acids. The antimicrobial activities of extracts were investigated by agar well diffusion method. Methanol-acid and ethanol-acid extracts exhibited the highest antimicrobial effects on all tested microorganisms, giving inhibition zones ranging in size from 17 to 36 mm. Although similar antimicrobial activities were observed by ethanol, methanol, and acetone extracts (up to 24 mm), the lowest antimicrobial activities were attained by water extract (0-15 mm). All extracts were generally more effective against Gram-positive bacteria: Enterococcus facealis, Bacillus subtilis, Bacillus cereus than Gram-negative ones: Escherichia coli and Enterobacter aerogenes. It was shown that extracts from pomegranate peels represent a good source of bioactive compounds.

Pomegranate Fruit Growth and Skin Characteristics in Hot and Dry Climate

Pomegranate (Punica granatum L.) fruit is well known for its health-beneficial metabolites. The pomegranate peel consists of an inner thick spongy white tissue, and an outer smooth skin layer that accumulates anthocyanins in red cultivars when ripe. The skin is made up of epidermis cells covered by a cuticle, the latter being the first target of cracking and russeting. The present study focuses on the effect of Israel's hot and dry climate on pomegranate growth, to elucidate the derived effects on fruit skin characteristics and its putative resistance to the building pressure from fruit expansion. Experiments were conducted for four years, in four orchards located in different regions of the country, each with a different typical microclimate. Fruit-growth parameters were followed using remote-sensing tools, microscopic study, and mineral analysis of the skin, followed by determination of the peel's elastic modulus. Fruit expanded in two phases: a short rapid phase followed by a gradual phase with a sigmoidal growth-rate pattern. Extreme hot and dry climate during the period of maximal growth rate was associated with restricted growth and a high proportion of small-size fruit. Anatomical study indicated that the skin of mature pomegranate fruit is made up of epidermal cells that are relatively flat and spaced apart, and is expected to be less durable against internal pressure. In contrast, skin of early immature fruit has two layers of dense and rounded epidermis, and is expected to be more resistant to cracking. Tensile strength studies confirmed this trend-skin of mature fruit had a lower elastic modulus than young fruit. However, restrained growth due to extreme environmental cues may result in better resistance of the mature pomegranate fruit to cracking, and in better skin quality and appearance, albeit small fruits. On the other hand, temperate climate at the beginning of the growth period, which allows high growth rate and high daily shrinkage, leads to pomegranate skin disorders.

Innovative Skin Product Emulsions with Enhanced Antioxidant, Antimicrobial and UV Protection Properties Containing Nanoparticles of Pure and Modified Chitosan with Encapsulated Fresh Pomegranate Juice

In the present study, a chitosan (CS) derivative with the 2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SDAEM) zwitterionic monomer was prepared through chemical modification. The successful synthesis of CS-SDAEM was confirmed by Fourier-transform Infrared (FTIR) and Nuclear Magnetic Resonance (¹H-NMR) spectroscopies. Its crystallinity was studied by X-ray Diffraction (XRD), while in vitro cytotoxicity and cell viability assays established its biocompatibility. Filtered fresh pomegranate juice (PJ) was loaded in nanoparticles of neat CS and its derivative via ionic gelation method. Dynamic Light Scattering (DLS) revealed nanoparticles sizes varying between 426 nm and 4.5 μm, indicating a size-dependence on the polymer concentration used during encapsulation. High-performance liquid chromatography coupled with photodiode array and electrospray ionization mass spectrometry detection (LC-PDA-ESI/MS) revealed that PJ active compounds were successfully and in sufficient amounts encapsulated in the nanoparticles interior, whereas XRD indicated a crystalline structure alteration after nanoencapsulation. The resulted PJ-loaded nanoparticles were further utilized for the preparation of innovative O/W cosmetic emulsions. All produced emulsions exhibited good pH and viscosity stability for up to 90 days, while the sun protection factor (SPF) was enhanced due to the presence of the PJ. Enhanced antioxidant and antimicrobial properties due to the phenolic compounds of PJ were also observed.

Combined Effect of Spirulina Platensis and Punica Granatum Peel Extacts: Phytochemical Content and Antiphytophatogenic Activity

Biological control is one of the effective methods for managing plant diseases in food production and quality. In fact, there is a growing trend to find new bio-sources, such as marine algae and vegetal by-products. In this study, pomegranate (Punica granatum) peel (S1) and Spirulina platensis (S2) alone and in combinations, pomegranate peel/Spirulina: 25%/75% (S3) and 50%/50% (S4) were evaluated for antimycotoxigenic and antiphytopathogenic fungal properties. The chemical composition (moisture, dry matter, protein, lipid and ash) as well as total polyphenols, flavonoids and anthocyanins content were evaluated in the four extracts. Using agar diffusion and broth microdilution methods, the anti Fusarium oxysporum, Fusarium culmorum, Fusarium graminearum, Aspergillus niger and Alternaria alternata activities were measured and their correlations with phytochemical content were evaluated. Interestingly, combinations between Spirulina at 75% and pomegranate peel at 25% (S3) have a significant impact (p < 0.05) on the antifungal activity compared to S1, S2 and S4. These findings underlie the effectiveness of biocontrols over standard fungicides and imply that existing methods can be further improved by synergistic effects while maintaining food safety in an eco-friendly manner.

Multiresponse Optimization of Pomegranate Peel Extraction by Statistical versus Artificial Intelligence: Predictive Approach for Foodborne Bacterial Pathogen Inactivation

Pomegranate (Punica granatum L.) peel is a potential source of polyphenols known for their activity against foodborne pathogen bacteria. In this study, the effects of pomegranate peel extraction time (10–60 min), agitation speed (120–180 rpm), and solvent/solid ratio (10–30) on phytochemical content and antibacterial activity were determined. Response surface methodology (RSM) and artificial neural network (ANN) methods were used, respectively, for multiresponse optimization and predictive modelling. Compared with the original conditions, the total phenolic content (TPC), the total flavonoid content (TFC), and the total anthocyanin content (TAC) increased by 56.22, 63.47, and 64.6%, respectively. Defined by minimal inhibitory concentration (MIC), the maximum of antibacterial activity was higher than that from preoptimized conditions. With an extraction time of 11 min, an agitation speed 125 rpm, and a solvent/solid ratio of 12, anti-S. aureus activity remarkably decreased from 1.56 to 0.171 mg/mL. Model comparisons through the coefficient of determination (R²) and mean square error (MSE) showed that ANN models were better than the RSM model in predicting the photochemical content and antibacterial activity. To explore the mode of action of the pomegranate peel extract (PPE) at optimal conditions against S. aureus and S. enterica, Chapman and Xylose Lysine Deoxycholate broth media were artificially contaminated at 10⁴ CFU/mL. By using statistical approach, linear (ANOVA), and general (ANCOVA) models, PPE was demonstrated to control the two dominant foodborne pathogens by suppressing bacterial growth.

The Odyssey of Bioactive Compounds in Avocado (Persea americana) and Their Health Benefits

Persea americana, commonly known as avocado, has recently gained substantial popularity and is often marketed as a "superfood" because of its unique nutritional composition, antioxidant content, and biochemical profile. However, the term "superfood" can be vague and misleading, as it is often associated with unrealistic health claims. This review draws a comprehensive summary and assessment of research performed in the last few decades to understand the nutritional and therapeutic properties of avocado and its bioactive compounds. In particular, studies reporting the major metabolites of avocado, their antioxidant as well as bioavailability and pharmacokinetic properties, are summarized and assessed. Furthermore, the potential of avocado in novel drug discovery for the prevention and treatment of cancer, microbial, inflammatory, diabetes, and cardiovascular diseases is highlighted. This review also proposes several interesting future directions for avocado research.

Pomegranate peel as phenolic compounds source: Advanced analytical strategies and practical use in meat products

The growing demand for natural food preservatives has promoted investigations on their application for preserving perishable foods. Consequently, the meat market is demanding natural antioxidants, free of synthetic additives and able to diminish the oxidation processes in high-fat meat and meat products. In this context, the present review discuss the development of healthier and shelf stable meat products by the successful use of pomegranate peel extracts containing phenolics as natural preservative agent in meat and meat products. This paper carries out an exhaustive review of the scientific literature on the main active phenolic compounds of pomegranate peel identified and quantified by advances in the separation sciences and spectrometry, and its biological activities evaluation. Moreover, the impact of pomegranate peel use on the quality and oxidative stability of meat products is also evaluated. As natural preservative, pomegranate peel phenolics could improve stored meat products quality, namely instrumental color retaining, limitaion of microflora growth, retardation of lipid and protein oxidation.

Shelf life and biochemical changes of ready-to-eat arils among nineteen Iranian pomegranate cultivars (Punica granatum L.) during storage

The objective of this study was to investigate the shelf life of arils and the changes in their biochemical compounds in nineteen Iranian pomegranate cultivars during storage. Fruits were harvested when commercially mature and the arils were removed, packaged and stored at 5 ± 1 °C, at 85-90% relative humidity in a cold room. Samples of the stored arils were examined for biochemical features in temporal checkpoints throughout a storage period that lasted for 35 days. By using the onset of decay as an index, the shelf life of arils varied among cultivars, ranging from 7 days to approximately 21 days. Considering the quality attributes of ready-to-eat arils at the beginning of the experiment, substantial variations were observed among the cultivars with regard to their titratable acidity (0.50-8.47%), total soluble solids (13-18.66 °Brix), DPPH radical scavenging activity (63-87.44%), Gallic-acid-equivalent (2.64-6.95 mg/ml) and ascorbic acid (12.21-75.09 mg/l). In general, the decay of arils gradually increased during storage, but several cultivars-which exhibited a very slow process of decay-contained the highest content of titratable acidity, Gallic-acid-equivalent and total soluble solids (since the signs of decay appeared on around the twenty-first day of storage). In addition, titratable acidity increased slightly by the end of storage, whereas the ascorbic acid content, total soluble solids and Gallic-acid-equivalent were cultivar-dependent and did not show consistent patterns of change during storage.

Physicochemical evaluation of corn extrudates containing varying buckwheat flour levels prepared at various extrusion temperatures

This study analyzed the characteristics (physicochemical properties as well as antioxidant activity) of corn grit extrudates containing buckwheat flour at various levels (0, 10, 20 and 30% w/w) extruded at various temperatures (130, 150 and 170 °C). Effect of roasting (92 °C for 15 min) on the extrudates was also studied. Buckwheat incorporation at different levels mainly increased the diameter, a* value (indicating redness), phenolic content and antioxidant capacity, while decreased bulk density and water absorption index of the extruded products. On the other hand, increment in extrusion temperature primarily increased the L* values (lightness), a* values and antioxidant activity but decreased the phenolic content of extrudates. Roasting improved the flavor and texture of the extrudates which was desirable. Extrudates prepared from corn grit with incorporation of buckwheat up to 20% level and extrusion cooking at 150 °C showed best sensory scores.