Anti-breast cancer activity of the essential oil from grapefruit mint (Mentha suaveolens × piperita).

Grapefruit mint (Mentha suaveolens × piperita) is a hybrid, perennial, and aromatic plant widely cultivated all over the world and used in the food, cosmetics, and pharmaceutical industries mostly for its valuable essential oil. Herein, we evaluated the anticancer activity of the grapefruit mint essential oil, cultivated in Iran. For the chemical composition analysis of essential oil, GC-MS was used. MTT assay was utilized for assessing the cytotoxic activity of the essential oil. The type of cell death was determined by annexin V/PI staining. Essential oil effect on the expression of maternally expressed gene 3 (MEG3), a regulatory lncRNA involved in cell growth, proliferation, and metastasis, was studied using qRT-PCR. Linalool (43.9%) and linalool acetate (40.1%) were identified as the dominant compounds of essential oil. Compared with MCF-7, the MDA-MB-231 cells were more sensitive to essential oil (IC50 = 7.6 µg/ml in MCF-7 and 5.9 µg/ml in MDA-MB-231 after 48 h). Essential oil induced cell death by apoptosis. Wound healing scratch assay confirmed the anti-invasive effect of essential oil. In addition, essential oil upregulated the tumor suppressor MEG3 in breast cancer cells. These results provide new insights into grapefruit mint essential oil potential application as an anticancer adjuvant in combination treatments for breast cancer patients.

Ex Vivo Anti-Leukemic Effect of Exosome-like Grapefruit-Derived Nanovesicles from Organic Farming-The Potential Role of Ascorbic Acid.

Citrus fruits are a natural source of ascorbic acid, and exosome-like nanovesicles obtained from these fruits contain measurable levels of ascorbic acid. We tested the ability of grapefruit-derived extracellular vesicles (EVs) to inhibit the growth of human leukemic cells and leukemic patient-derived bone marrow blasts. Transmission electron microscopy and nanoparticle tracking analysis (NTA) showed that the obtained EVs were homogeneous exosomes, defined as exosome-like plant-derived nanovesicles (ELPDNVs). The analysis of their content has shown measurable amounts of several molecules with potent antioxidant activity. ELPDNVs showed a time-dependent antiproliferative effect in both U937 and K562 leukemic cell lines, comparable with the effect of high-dosage ascorbic acid (2 mM). This result was confirmed by a clear decrease in the number of AML blasts induced by ELPDNVs, which did not affect the number of normal cells. ELPDNVs increased the ROS levels in both AML blast cells and U937 without affecting ROS storage in normal cells, and this effect was comparable to ascorbic acid (2 mM). With our study, we propose ELPDNVs from grapefruits as a combination/supporting therapy for human leukemias with the aim to improve the effectiveness of the current therapies.

Randomized Controlled Study in the Use of Aromatherapy for Pain Reduction and to Reduce Opioid Use in the Emergency Department.

INTRODUCTION: This study aimed to evaluate the effects of aromatherapy on emergency department patients' perception of pain and its ability to reduce the use of opioids in an emergency department. METHODS: This randomized, controlled, single-blinded study was conducted in a suburban/rural freestanding emergency department with a therapeutic group, sham group, and control group. RESULTS: A total of 230 patients, 171 females and 59 males, completed the study. Of those who received the therapeutic agent, an average reduction in pain of 1.04 points on the pain scale was reported, whereas the sham group averaged 0.38 and the control group 0.23. There was a statistically significant reduction of pain scores in the therapeutic group. A total of 13 received opioid pain medication during their visit. Of these, the therapeutic group averaged a total of 2.67 morphine milligram equivalents for their visit compared with 3.63 in the sham group and 4.36 in the control group; however, statistical significance was not achieved. DISCUSSION: This study supported what other studies have found, indicating that aromatherapy is effective in reducing pain. A difference between the placebo effect and a true therapeutic effect was seen by using a control group apart from the sham and therapeutic groups. Despite the small effect size (0.3), implementation of aromatherapy into standard practice may be practical considering the anxiolytic effects that have been shown in other studies. Aromatherapy with essential oils should be considered as another tool to use in a multimodal approach in the treatment of pain in the emergency department setting.

Examining the Naringin Content and Sensory Characteristics of Functional Chocolate Fortified with Grapefruit Peel Extract.

Grapefruit peel contains a high concentration of naringin- a potent antioxidant with strong bioactive properties. In this study, a new type of functional chocolate fortified with grapefruit peel extract and different concentrations of aqueous methanol and ethanol were evaluated as extraction solvents. A new high-performance liquid chromatography (HPLC) method to analyze the naringin content of the fortified chocolates was developed with a recovery of 107% ± 3.1% and repeatability below 3.5%. A sensory evaluation was conducted to assess the preference for the chocolates among individuals who self-described a preference for bitter flavors. No significant preference was observed in the cases of astringency and aftertaste while the increased bitterness proved to be favorable. However, taste, flavor and overall acceptability were regarded somewhat less favorably. While chocolate proved to be a satisfactory carrier for naringin and had several enjoyable characteristics, further research may focus on improving the organoleptic properties of chocolates fortified by naringin.

Chondroprotective Effects of Grapefruit (Citrus paradisi Macfad.) Juice in a Complete Freund's Adjuvant Rat Model of Knee Osteoarthritis.

Osteoarthritis (OA) is a common disorder that can affect any joint in the human body. This study aimed to examine the anti-arthritic properties of high and low doses of grapefruit juice (GFJ), as grapefruit appears to contain anti-inflammatory biochemicals. Forty male Sprague-Dawley rats weighing 170-180 g were divided into five groups. These groups comprised the untreated control group and osteoarthritic (Osteo) rats administered intra-articular injections of Freund's complete adjuvant (CFA; 0.5 mL; 1 mg/mL) as follows: OA rats administered low doses of GFJ (Osteo+GFJ (low); 5 mL/kg body weight (BW)); OA rats administered high doses of GFJ (Osteo+GFJ (high); 27 mL/kg BW); and OA rats administered diclofenac sodium (Osteo+Diclo) as a reference drug. Injections of CFA induced OA, as indicated by a significant increase in the serum levels of the inflammatory biomarkers C-reactive protein (CRP), interleukin-1ß (IL-1ß), and (prostaglandin (PGE2), as well as matrix metalloproteinases (MMP-1) and cathepsin K. The synovial levels of glycosaminoglycans (GAGs), tumor necrosis factor (TNF-α), and interleukin 6 (IL-6) also increased, with a concomitant reduction in osteocalcin levels. The administration of either high or low doses of GFJ reduced CRP, IL-1ß, PGE2, MMP-1, cathepsin K, and osteocalcin while increasing the synovial levels of GAGs, TNF-α, and IL-6, slowing cartilage degradation and boosting joint function. The results showed comparable histopathological and biochemical responses. A comparison of the treatments showed that high-dose GFJ had a greater chondroprotective effect than low-dose GFJ.

Gelatin/poly(vinyl alcohol)-based functional films integrated with spent coffee ground-derived carbon dots and grapefruit seed extract for active packaging application.

Nanoparticles are attractive, functional additives with great potential to be applied in biomaterial and food packaging. However, these particles are not soluble in water, thus limiting their widespread application. Here, we report a facile fabrication of carbon dots (CDs) using the spent coffee ground as the carbon source through a hydrothermal method. The CD was added to the gelatin/poly(vinyl alcohol) (Gel/PVA) film and grapefruit seed extract (GSE) to prepare multifunctional packaging films. The functional films' physiochemical and functional properties and packaging application were investigated. The composite film showed good UV protection properties with a slight decrease in transparency. The composite film containing CD/GSE showed strong antioxidant activity, scavenging >38 % DPPH and 100 % ABTS radicals. The film also exhibited significant antibacterial activity against the foodborne pathogens Listeria monocytogenes and Escherichia coli, completely eradicating the growth of these bacteria within 9 h of exposure. The CD/GSE-incorporated Gel/PVA films were used for pork packaging. The films were able to enhance the pork shelf life by reducing the L. monocytogenes bacterial growth in meat by 2 Log CFU/mL lower than the control wrapping film. The multifunctional Gel/PVA films are expected to be used for the active packaging of meat products.

Antimicrobial, antioxidant, and pH-sensitive polyvinyl alcohol/chitosan-based composite films with aronia extract, cellulose nanocrystals, and grapefruit seed extract.

Aronia or black chokeberry (Aronia melanocarpa), cellulose nanocrystals (CNCs), and grapefruit seed extract (GSE) were used for the preparation of multifunctional polyvinyl alcohol/chitosan (PVA/CS) composite films with pH-sensitivity, antimicrobial, antioxidant, and UV-barrier properties. Aronia extract showed total phenolic content of 297 ± 0.5 µg GAE/mg aronia extract, potent antioxidant activity, and high color-response efficiency. Isolated CNCs showed a needle-like structure with a length of 470 nm and a width of 35 nm. The tensile strength of the PVA/CS composite film increased by 74% after the incorporation of CNCs, whereas the film flexibility was enhanced by 75% after adding GSE. The PVA/CS-A (aronia extract) composite film showed a significant color change at different pHs and potent antioxidant activity. At the same time, the PVA/CS-G (GSE) showed the highest antimicrobial activity against Escherichia coli (Gram-negative) and Listeria monocytogenes (Gram-positive) bacteria. The PVA/CS-CGA composite film, reinforced with CNCs/GSE/Aronia extract, showed the highest UV-barrier (95.5%), highest antioxidant activity (95%), potent antimicrobial activity, pH-sensitivity, lowest water vapor permeability (WVP), and desirable mechanical properties. The multifunctional properties of the produced composite films encourage their use as active and intelligent food packaging films to extend shelf life and monitor food quality.

Antifungal activity of Zinc nitrate derived nano Zno fungicide synthesized from Trachyspermum ammi to control fruit rot disease of grapefruit.

Grapefruit (Citrus paradisi) is a widely grown citrus and its fruit is affected by a variety of biotic and abiotic stress. Keeping in view the hazardous effects of synthetic fungicides, the recent trend is shifting towards safer and eco-friendly control of fruit diseases. The present study was aimed to diagnose the fruit rot disease of grapefruit and its control by using zinc oxide green nanoparticles (ZnO NPs). Fruit rot symptoms were observed in various grapefruit growing sites of Pakistan. Diseased samples were collected, and the disease-causing pathogen was isolated. Following Koch's postulates, the isolated pathogen was identified as Rhizoctonia solani. For eco-friendly control of this disease, ZnO NPs were prepared in the seed extract of Trachyspermum ammi and characterized. Fourier transform infrared spectroscopy (FTIR) of these NPs described the presence of stabilizing and reducing compounds such as phenols, aldehyde and vinyl ether, especially thymol (phenol). X-ray diffraction (XRD) analysis revealed their crystalline nature and size (48.52 nm). Energy dispersive X-ray (EDX) analysis elaborated the presence of major elements in the samples, while scanning electron microscopy (SEM) confirmed the morphology of bio fabricated NPs. ZnO NPs exhibited very good anti-fungal activity and the most significant fungal growth inhibition was observed at 1.0 mg/ml concentration of green NPs, in vitro and in vivo. These findings described that the bioactive constituents of T. ammi seed extract can effectively reduce and stabilize ZnO NPs. It is a cost-effective method to successfully control the fruit rot disease of grapefruit.

Effects of Citri Reticulatae Pericarpium and grapefruit juice on the pharmacokinetics of omeprazole in rats.

The effects of Citri Reticulatae Pericarpium (CRP) and grapefruit juice (GFJ) on the pharmacokinetics of omeprazole were investigated in this study. Sprague-Dawley rats were pretreated with CRP decoction or GFJ for 28 consecutive days. After a single intragastric administration of 6.0 mg/kg, the concentration of omeprazole in the plasma was determined by high-performance liquid chromatography (HPLC), and the pharmacokinetic parameters were calculated by Kinetica software 5.0. A high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (HPLC-Q-TOF-MS) method was established to identify the chemical components in CRP decoction and GFJ. The results showed that the AUCt-∞ was significantly increased when coadministrated with CRP. The AUC0-t and AUC0-∞ was remarkably increased; the Cl was decreased when coadministrated with GFJ. A total of 31 and 28 bioactive compounds were identified in the CRP decoction and GFJ, respectively. Flavonoids and furanocoumarins, including hesperidin, hesperetin, naringenin, sinensetin, tangeretin, nobiletin, and 6',7'-dihydroxybergamottin, were simultaneously identified in CRP decoction and GFJ. This study indicates that the increased bioavailability of omeprazole may be due to the inhibition of hepatic cytochrome P450 enzymes, and the systemic exposure should be monitored when concomitant administration with CRP and GFJ. PRACTICAL APPLICATIONS: Citri Reticulatae Pericarpium (CRP) has been widely consumed as a daily condiment, functional food, and a traditional Chinese medicine. Omeprazole, primary metabolized by CYP450 enzymes, was usually coadministered with CRP for the treatment of gastrointestinal disease. Studies have confirmed that much fruit juices, including grapefruit juice, may affect drug metabolism enzymes. CRP and grapefruit (Citrus paradisi Macf.) belong to the genus Citrus and family Rutaceae with different species. Therefore, the pharmacokinetic interaction of CRP decoction and grapefruit juice with omeprazole is worthy of attention. The results of this study can provide basic pharmacological data support for the safe and effective clinical use of omeprazole. It can also provide a theoretical basis for the development of new functional products and daily application of CRP.

Role of Citrus Fruit Juices in Prevention of Kidney Stone Disease (KSD): A Narrative Review.

To explore the relationship between citrus fruit juices (oranges, grapefruits, and lemonades) and kidney stone disease (KSD). METHODS: A systematic review was performed using the Medline, EMBASE, and Scopus databases, in concordance with the PRISMA checklist for all English, French, and Spanish language studies regarding the consumption of citrus fruit juices and the relationship to urinary stone disease. The main outcome of interest was the association of citrus fruit juices with KSD. RESULTS: Thirteen articles met the criteria for inclusion in the final review. Three large epidemiological studies found that grapefruit juice was a risk factor for stone formation, while orange juice did not increase the risk for KSD. Ten small prospective clinical studies found that orange, grapefruit, and lemon juices all increased urinary citrate levels. Only orange and grapefruit juices had an alkalinizing effect and while lemon juice has a protective effect by raising urinary citrate levels, it lacked a significant alkalinizing effect on urine pH. Orange juice and grapefruit juices significantly increased urinary oxalate levels, while orange juice also had a high carbohydrate content. CONCLUSION: While orange juice seems to play a protective role against stone formation, grapefruit was found to raise the risk of KSD in epidemiological studies but had a protective role in smaller clinical studies. Lemon juice had a smaller protective role than orange juice. Larger amounts of, as well as more accurate, data is needed before recommendations can be made and a high carbohydrate content in these juices needs to be taken into consideration.

Chemical Profiling, Toxicity and Anti-Inflammatory Activities of Essential Oils from Three Grapefruit Cultivars from KwaZulu-Natal in South Africa.

The medicinal potential and volatile composition of different parts of three cultivars of grapefruit (Citrus paradisi) were evaluated for their toxicity and anti-inflammatory activities. Fresh leaf and fruit peel were separately isolated by hydrodistillation for 4 h. The essential oils were subjected to GC/GC-MS analysis for chemical profile. Toxicity of the essential oils in mice were evaluated using Lorke's method, while an anti-inflammatory assay was performed in a rat model using egg albumin-induced oedema. The oils obtained were light yellow in colour, and odour varied from strong citrus smell to mild. Percentage yield of fresh peel oil (0.34-0.57%) was greater than the fresh leaf oil yield (0.21-0.34%). D-limonene (86.70-89.90%) was the major compound identified in the leaf oil, while ß-phellandrene (90.00-91.01%) dominated the peel oil. At a dosage level of 5000 mg/kg, none of the oils showed mortality in mice. An anti-inflammatory bioassay revealed that all the oils caused a significant (p < 0.05-0.01) reduction in oedema size when compared to the negative control group throughout the 5 h post induction assessment period. The study reveals that the oils are non-toxic and demonstrate significant anti-inflammatory activity. Our findings suggest that the leaf and peel oils obtained from waste parts of grapefruit plants can be useful as flavouring agents, as well as anti-inflammatory agents.

Using essential oils from Citrus paradisi as a fumigant for Solenopsis invicta workers and evaluating the oils' effect on worker behavior.

The red imported fire ant is one of the world's most devastating invasive species, adversely affecting humans, wildlife, crops, and livestock. To control infestations, chemical pesticides are deployed extensively around the world. However, their extensive use has led to negative effects on the environment and human health. Essential oils, which are safe and ecofriendly, can potentially be used as alternatives to chemical pesticides. In this study, grapefruit essential oils were used as fumigant agents to control red imported fire ants. The crude grapefruit oil (GO1) contained 28 compounds, and the concentrated grapefruit oil (GO2), which was refined from GO1 by vacuum distillation, contained 20 compounds. D-Limonene was the dominant constituent in both GO1 (70.1%) and GO2 (73.96%), and other important constituents included ß-pinene, α-pinene, ß-phellandrene, octanal, d-carvone, α-terpineol, and linalool. Both the essential oils and their individual constituents (α-pinene, α-terpineol, ß-phellandrene, octanal, and d-carvone) showed strong lethal fumigant effects against workers. Workers were more susceptible to GO2 than GO1, and octanal was more toxic to workers as compared with the other four constituents. When antennas of workers were treated with the two oils or the five constituents, their walking and gripping abilities were significantly suppressed, and there was an obvious bending or breaking phenomenon on the sensilla of the antennas. Fumigant activity by grapefruit essential oils and their main compounds were associated with their effects on the walking and gripping behavior of workers, and this confirmed that grapefruit essential oil is a promising, ecofriendly, and safe fumigant for the control of red imported fire ants.

Parallel evolution of UbiA superfamily proteins into aromatic O-prenyltransferases in plants.

Plants produce ∼300 aromatic compounds enzymatically linked to prenyl side chains via C-O bonds. These O-prenylated aromatic compounds have been found in taxonomically distant plant taxa, with some of them being beneficial or detrimental to human health. Although their O-prenyl moieties often play crucial roles in the biological activities of these compounds, no plant gene encoding an aromatic O-prenyltransferase (O-PT) has been isolated to date. This study describes the isolation of an aromatic O-PT gene, CpPT1, belonging to the UbiA superfamily, from grapefruit (Citrus × paradisi, Rutaceae). This gene was shown responsible for the biosynthesis of O-prenylated coumarin derivatives that alter drug pharmacokinetics in the human body. Another coumarin O-PT gene encoding a protein of the same family was identified in Angelica keiskei, an apiaceous medicinal plant containing pharmaceutically active O-prenylated coumarins. Phylogenetic analysis of these O-PTs suggested that aromatic O-prenylation activity evolved independently from the same ancestral gene in these distant plant taxa. These findings shed light on understanding the evolution of plant secondary (specialized) metabolites via the UbiA superfamily.

Citrus decoction by-product represents a rich source of carotenoid, phytosterol, extractable and non-extractable polyphenols.

This study aimed to carry out an exhaustive chemical characterization of citrus (orange, mandarin, and grapefruit) decoctions as well as the residues obtained during the decoction process (by-products). The citrus decoctions were rich in hesperidin, naringin, and narirutin, but carotenoids and phytosterols were not detected. Interestingly, these flavanones were found in a higher concentration in the extractable polyphenol fraction of the citrus decoction by-products. Moreover, the greatest content of hesperidin and naringin was found bound to the food matrix by ether/ester bonds. Violaxanthin and ß-cryptoxanthin were found as major carotenoids in the orange and mandarin decoction by-products, respectively, whereas the grapefruit decoction by-product showed a low content of carotenoids. All citrus by-products showed ß-sitosterol as the major phytosterol, followed by ß-campesterol. Therefore, the by-products obtained during the elaboration of citrus decoctions are rich sources of bioactive compounds that can be used for the development of functional foods or dietary supplements.

Grapefruit Seed Extract as a Natural Derived Antibacterial Substance against Multidrug-Resistant Bacteria.

Multidrug-resistant (MDR) bacteria are increasing due to the abuse and misuse of antibiotics, and nosocomial infections by MDR bacteria are also increasing. The aim of this study was to identify new substances that can target MDR bacteria among 12 plant extracts that are known to have antibacterial effects. The experiments were performed by the disk diffusion test and microdilution minimum inhibitory concentration (MIC) test, as described by the Clinical and Laboratory Standards Institute (CLSI). By screening against methicillin-sensitive Staphylococcus aureus (MSSA), grapefruit seed extract (GSE) was selected from 12 plant extracts for subsequent experiments. GSE showed antibacterial effects against methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) in the disk diffusion test. Even at the lowest concentration, GSE showed antibacterial activity in the microdilution MIC test. As a result, we can conclude that GSE is a naturally derived antibacterial substance that exhibits a favorable antibacterial effect even at a very low concentration, so it is a good candidate for a natural substance that can be used to prevent or reduce nosocomial infections as coating for materials used in medical contexts or by mixing a small amount with other materials.

A Biomimetic Drug Delivery System by Integrating Grapefruit Extracellular Vesicles and Doxorubicin-Loaded Heparin-Based Nanoparticles for Glioma Therapy.

Existing nanoparticle-mediated drug delivery systems for glioma systemic chemotherapy remain a great challenge due to poor delivery efficiency resulting from the blood brain barrier/blood-(brain tumor) barrier (BBB/BBTB) and insufficient tumor penetration. Here, we demonstrate a distinct design by patching doxorubicin-loaded heparin-based nanoparticles (DNs) onto the surface of natural grapefruit extracellular vesicles (EVs), to fabricate biomimetic EV-DNs, achieving efficient drug delivery and thus significantly enhancing antiglioma efficacy. The patching strategy allows the unprecedented 4-fold drug loading capacity compared to traditional encapsulation for EVs. The biomimetic EV-DNs are enabled to bypass BBB/BBTB and penetrate into glioma tissues by receptor-mediated transcytosis and membrane fusion, greatly promoting cellular internalization and antiproliferation ability as well as extending circulation time. We demonstrate that a high-abundance accumulation of EV-DNs can be detected at glioma tissues, enabling the maximal brain tumor uptake of EV-DNs and great antiglioma efficacy in vivo.

Preparation of nanofibrillated cellulose from grapefruit peel and its application as fat substitute in ice cream.

Grapefruit peel nanofibrillated cellulose (GNFC) was used as fat substitute in ice cream. GNFC was characterized by TEM, SEM, and XRD. The effects of GNFC on textural profiles, rheological properties, melting resistance, sensory properties, microstructure, and gross energy (GE) of ice cream were investigated. The results showed that GNFC was short rod-shaped crystal. Ice cream added with GNFC exhibited elastic-dominated behavior and better textural properties. The sensory evaluation score reached the highest level with desirable three-dimensional network structure at 0.4 % GNFC addition. GE of ice cream significantly decreased with reducing fat with maximal reduction rate of 17.90 %. Furthermore, the results of in vitro simulated digestion showed that GNFC addition and fat reduction significantly inhibited fat digestibility of ice cream due to coalescence of fat droplets on GNFC. This study provides new sustainable perspectives for the application of GNFC prepared from agricultural waste as fat substitute in food products.

Ultrasound-assisted development of stable grapefruit peel polyphenolic nano-emulsion: Optimization and application in improving oxidative stability of mustard oil.

Grapefruit (Citrus paradisi) peel (GP) is rich in flavonoids and phenolics which have several proven pharmacological effects. However, their chemical instability towards oxygen, light and heat limits its applications in food industries. In the present study, we evaluated the feasibility of fabricating grapefruit-peel-phenolic (GPP) nano-emulsion in mustard oil using ultrasonication. Response surface methodology (RSM) optimization revealed that sonication time of 9.5 min at 30% amplitude and 0.52% Span-80 produced the stable GPP nano-emulsion with a droplet size of 29.73 ± 1.62 nm. Results indicate that both ultrasonication and Span-80 can assist the fabrication of a stabilized nano-emulsion. This study is one of its kind where nano-encapsulation of GPP into W/O emulsion was done to stabilize the active compound inside mustard oil and then the nano-emulsion was used to extend oxidative stability of mustard oil. Findings provide a basic guideline to formulate stable nano-emulsions for their use in active food packaging, oils, and pharmaceuticals.

A New Water-Soluble Bactericidal Agent for the Treatment of Infections Caused by Gram-Positive and Gram-Negative Bacterial Strains.

Grapefruit and lemon pectin obtained from the respective waste citrus peels via hydrodynamic cavitation in water only are powerful, broad-scope antimicrobials against Gram-negative and -positive bacteria. Dubbed IntegroPectin, these pectic polymers functionalized with citrus flavonoids and terpenes show superior antimicrobial activity when compared to commercial citrus pectin. Similar to commercial pectin, lemon IntegroPectin determined ca. 3-log reduction in Staphylococcus aureus cells, while an enhanced activity of commercial citrus pectin was detected in the case of Pseudomonas aeruginosa cells with a minimal bactericidal concentration (MBC) of 15 mg mL-1. Although grapefruit and lemon IntegroPectin share equal MBC in the case of P. aeruginosa cells, grapefruit IntegroPectin shows boosted activity upon exposure of S. aureus cells with a 40 mg mL-1 biopolymer concentration affording complete killing of the bacterial cells. Insights into the mechanism of action of these biocompatible antimicrobials and their effect on bacterial cells, at the morphological level, were obtained indirectly through Fourier Transform Infrared spectroscopy and directly through scanning electron microscopy. In the era of antimicrobial resistance, these results are of great societal and sanitary relevance since citrus IntegroPectin biomaterials are also devoid of cytotoxic activity, as already shown for lemon IntegroPectin, opening the route to the development of new medical treatments of polymicrobial infections unlikely to develop drug resistance.

Effects of mung bean starch/guar gum-based edible emulsion coatings on the staling and safety of rice cakes.

Antimicrobial starch/gum-based edible emulsion coatings were developed to improve the storage stability of rice cakes by retarding starch retrogradation and inhibiting microbial growth. Rice cakes were coated with mung bean starch (MBS) and guar gum (GG) containing various concentrations of sunflower seed oil (SO). Among these, the (2 g MBS +0.75 g GG +1.5 g SO) / 100 g (optimum) decreased the hardness of rice cakes by 29 % and the crystallization rate (k) by 24 % compared with those of uncoated samples. The moisture loss in uncoated samples was markedly higher than that in the optimum blend-coated samples. Crystallinity analysis revealed the retarding effect of the developed coatings in starch retrogradation. Furthermore, adding 0.8 % (w/w) grapefruit seed extract to the optimum blend led to a distinct antimicrobial activity. Therefore, the newly developed edible coating was effective in maintaining the quality and safety of rice cakes.