Valorisation of Three Underutilised Native Australian Plants: Phenolic and Organic Acid Profiles and In Vitro Antimicrobial Activity.

Tasmannia lanceolata, Diploglottis bracteata and Syzygium aqueum are understudied native Australian plants. This study aimed to characterise the non-anthocyanin phenolic and organic acid profiles of the aqueous extracts obtained from the leaves of T. lanceolata and fruits of D. bracteata and S. aqueum by UHPLC-Q-Orbitrap-MS/MS and UHPLC-TQ-MS/MS. A total of 39, 22, and 27 non-anthocyanin polyphenols were tentatively identified in T. lanceolata, D. bracteata, and S. aqueum extracts, respectively. Furthermore, sugars and ascorbic acid contents as well as in vitro antioxidant and antimicrobial activities of the extracts were determined. Response surface methodology was applied to achieve an extract blend with a strong inhibitory effect against Pseudomonas viridiflava, the main cause of soft rot in vegetables, Bacillus subtilis, Rhodotorula diobovata and Alternaria alternata. The identified compounds including organic acids (e.g., quinic, citric and malic acids) and polyphenols (e.g., catechin, procyanidins, and ellagitannins) might contribute to the observed antimicrobial activity. Furthermore, this study provides the most comprehensive phenolic profiles of these three underutilised native Australian plants to date.

Investigating the Efficacy of Tasmannia lanceolata Extract in Inactivating Fungi and Prolonging the Shelf Life of Date Fruit.

Date palm (Phoenix dactylifera L.) is one of the world's oldest cultivated plants. Post-harvest losses of date palm due to fungal contamination reached up to 50% of the total production. This study aimed to investigate the potential of the extract of Tasmanian pepper leaf (TPL) and the non-thermal treatment of photosensitization mediated by curcumin in reducing the fungal contamination and enhancing the shelf life of date palm. In the in vivo storage study, the dates were treated with three different concentrations of TPL extract 12.5, 25, and 50 µg/mL and stored at 30 °C. The findings obtained for the treatment with TPL extract exhibited potent antifungal activity against most of the tested fungi, where minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) were < 25 µg/mL for polygodial, the bioactive compound in TPL. The shelf life of date palm treated by 50 µg/mL polygodial was extended up to 21 days, thrice as much as the untreated controls. In contrast, a lower concentration of TPL extract (25 µg/mL polygodial) revealed up to a 15-day shelf life extension compared to untreated dates (7 days). The results obtained from the study suggested that using TPL extracts against pathogenic and spoilage fungi occurring in fresh date fruits is a promising treatment for the shelf life extension of fresh date fruits at room temperature.

Recent developments in emerging technologies for beetroot pigment extraction and its food applications.

Beetroot is well known for its deep red-purple colouring pigments called betalains. Betalains also found its application in the preparation of functional foods and drinks. Therefore, extraction of pigments with higher recovery and stability is the prime need for the industry. Conventional extraction techniques such as maceration, grinding or pressing have reported low yield of betalains and required large volume of solvent and energy. On the other hand, emerging technologies such as ultrasound, microwave and pulse electric field techniques are highly efficient processes and can achieve higher recovery. In this regard, this review provides an in-depth discussion on the various extraction methods and factors affecting the stability of betalains using conventional and emerging technologies. The recent applications of pigments in various food systems are also presented. Finally, challenges and future prospects of extraction and application of beetroot pigment have been identified and discussed.

Biochemical, antioxidant and sensory evaluation of Davidsonia pruriens and Davidsoina jerseyana fruit infusion.

Davidsonia pruriens (DP) and Davidsonia jerseyana (DJ) are a gourmet bushfood with a sweet and sour taste. This study investigated the biochemical content, antioxidant activities, and sensory attributes of DP and DJ fruit infusions in comparison with commercial forest fruits (FF) infusion. Total phenolic and anthocyanin content was higher in FF infusion compared to DP or DJ fruit infusions (P < 0.05). An abundant amount of gallic acid was found in DP and DJ fruit infusions (P < 0.05). Quercetin, kaempferol-3-O-rutinoside, and peonidin-3-sambubioside was detected only in DP and DJ fruit infusions (P < 0.05). However, a high level of oxalic acid, minerals and soluble sugars were observed in FF infusions (P < 0.05). The antioxidant capacities and overall likeness score of DP or DJ infusion were comparable with the commercial FF infusion. Therefore, bioactive compounds, antioxidant activities and sensory properties suggested that DP and DJ fruit infusion have the potential to become a commercial health promoting drink.

An insight into curcumin-based photosensitization as a promising and green food preservation technology.

Consumer awareness on the side effects of chemical preservatives has increased the demand for natural preservation technologies. An efficient and sustainable alternative to current conventional preservation techniques should guarantee food safety and retain its quality with minimal side effects. Photosensitization, utilizing light and a natural photosensitizer, has been postulated as a viable and green alternative to the current conventional preservation techniques. The potential of curcumin as a natural photosensitizer is reviewed in this paper as a practical guide to develop a safe and effective decontamination tool for industrial use. The fundamentals of the photosensitization mechanism are discussed, with the main emphasis on the natural photosensitizer, curcumin, and its application to inactivate microorganisms as well as to enhance the shelf life of foods. Photosensitization has shown promising results in inactivating a wide spectrum of microorganisms with no reported microbial resistance due to its particular lethal mode of targeting nucleic acids. Curcumin as a natural photosensitizer has recently been investigated and demonstrated efficacy in decontamination and delaying spoilage. Moreover, studies have shown the beneficial impact of an appropriate encapsulation technique to enhance the cellular uptake of photosensitizers, and therefore, the phototoxicity. Further studies relating to improved delivery of natural photosensitizers with inherent poor solubility should be conducted. Also, detailed studies on various food products are warranted to better understand the impact of encapsulation on curcumin photophysical properties, photo-driven release mechanism, and nutritional and organoleptic properties of treated foods.

Effect of solid-state fermentation on proximate composition, anti-nutritional factor, microbiological and functional properties of lupin flour.

The effects of solid-state fermentation (SSF) with Aspergillus sojae, Aspergillus ficuum and their co-cultures on proximate composition, anti-nutritional factor, microbiological and functional properties of lupin flour (LF) were investigated. Fibre fractions, in vitro enzyme protein digestion (IVPD), total phenolic contents, protein molecular distribution and colour attributes were also evaluated. Samples differed in their proximate composition except ash and fibre contents. The microbiological counts of the fermented LFs were generally higher (p < 0.05) than that of the unfermented LF. Phytic acid content and IVPD decreased (p < 0.05) in the fermented LFs. Also, the fermented LFs showed decreased (p < 0.05) water absorption capacity but increased swelling capacity. In addition, fermented LFs demonstrated reduction in colour attributes. Thus, the study indicated that SSF using Aspergillus sojae and Aspergillus ficuum can influence the physical, chemical and functional properties of LF. LF has great potentials in developing new nutritious food products and feed formulations when subjected to SSF.

Solid-state fermented plant protein sources in the diets of broiler chickens: A review.

Protein sources are the second most important component in poultry diets. Due to the fluctuation in price of soybean meal (SBM) and persistent increase in feed prices, nutritionists have been exploring alternative protein sources. Replacement of SBM with alternative protein sources in poultry diets could reduce human-livestock competition for soybean and support the production of more animal protein. However, the use of alternative protein sources is limited to low inclusion due to the presence of anti-nutritional factors (ANF) such as glucosinolates (rapeseed meal), gossypol (cottonseed meal), non-starch polysaccharides (NSP) in lupin flour, high fibre (palm kernel cake), total phenolic contents and phytic acid (canola meal) known to impair animal performance, nutrient digestibility and feed utilization. As a processing technique, solid-state fermentation (SSF) has been researched for a long time in the food industry. An important objective of SSF is the production of enzymes, organic acids and other metabolites of economic importance. In recent times, SSF has been employed to enhance nutrient bioavailability, inhibit gut pathogenic bacteria and reduce ANF in plant protein sources resulting in improved nutrient digestibility, thereby improving performance and gut health of broiler chickens. Unlike pigs, there is still a dearth of information on feeding solid-state fermented feed ingredients to broiler chickens. This review aims to describe the nutritional value of the solid-state fermented products of rapeseed meal, canola meal, cottonseed meal, palm kernel cake and lupin flour on performance and intestinal health of broiler chickens.

Mechanism of Action against Food Spoilage Yeasts and Bioactivity of Tasmannia lanceolata, Backhousia citriodora and Syzygium anisatum Plant Solvent Extracts.

Bioactive properties of solvent extracts of Tasmannia lanceolata, Backhousia citriodora and Syzygium anisatum investigated. The antimicrobial activities evaluated using agar disc diffusion method against two bacteria (Escherichia coli and Staphylococcus aureus) and six weak-acid resistant yeasts (Candida albicans, Candida krusei, Dekkera anomala, Rhodotorula mucilaginosa, Saccharomyces cerevisiae and Schizosaccharomyces pombe). The antioxidant activities determined using DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging and reducing power assays. Quantification of major active compounds using ultra-high performance liquid chromatography. Extracts showed broad-spectrum antifungal activity against weak-acid resistant yeasts in comparison to the standard antifungal agents, fluconazole and amphotericin B. Dekkera anomala being the most sensitive and strongly inhibited by all extracts, while Escherichia coli the least sensitive. Polygodial, citral and anethole are the major bioactive compounds identified in Tasmannia lanceolata, Backhousia citriodora and Syzygium anisatum, respectively. Hexane extracts contain the highest amount of bioactive compounds and demonstrate the strongest antimicrobial activities. Methanol and ethanol extracts reveal the highest phenolic content and antioxidant properties. Fluorescence microscopic results indicate the mechanism of action of Backhousia citriodora against yeast is due to damage of the yeast cell membrane through penetration causing swelling and lysis leading to cell death.

Formulation, characterisation and antibacterial activity of lemon myrtle and anise myrtle essential oil in water nanoemulsion.

This study focussed on the formulation, characterisation of lemon myrtle (LM) and anise myrtle (AM) essential oil (EO) in water nanoemulsion and their antibacterial activity. The required hydrophilic lipophilic balance (rHLB) value of LM EO and AM EO was 14 and 12, respectively. The Central Composite Rotatable Design (CCRD) model produces the smallest droplet size and polydispersity index (PDI) for LMEO (d ≈ 16.07 nm; PDI ≈ 0.209) and AMEO (d ≈ 30.23 nm; PDI ≈ 0.216) at 1% EO and 10% surfactant mixture (Smix) ratio using ultrasonication for 5 min. Whereas, increased in EO, decrease in Smix concentrations and ultrasonication time produces higher droplet size of nanoemulsions. LMEO (LM-15, LM-17) nanoemulsions was clear and transparent compared to AMEO (AM-15, AM-17). All the selected nanoemulsions showed good stability at 4, 25 and 40 °C during storage, except LM-15 at 40 °C. LMEO nanoemulsion showed enhanced antibacterial activity compared to LMEO alone (P < 0.05).

A novel photosensitization treatment for the inactivation of fungal spores and cells mediated by curcumin.

The global concerns regarding the emergence of fungicide-resistant strains and the impact of the excessive use of fungicidal practises on our health, food, and environment have increased, leading to a demand for alternative clean green technologies as treatments. Photosensitization is a treatment that utilises a photosensitiser, light and oxygen to cause cell damage to microorganisms. The effect of photosensitization mediated by curcumin on Aspergillus niger, Aspergillus flavus, Penicillium griseofulvum, Penicillium chrysogenum, Fusarium oxysporum, Candida albicans and Zygosaccharomyces bailii was investigated using three methods. The viability of spores/cells suspended in aqueous buffer using different concentrations of curcumin solution (100-1000µM) and light dose (0, 24, 48, 72 and 96J/cm2) were determined. Spraying curcumin solution on inoculated surfaces of agar plates followed by irradiation and soaking spores/cells in curcumin solution prior to irradiation was also investigated. In aqueous mixtures, photosensitised spores/cells of F. oxysporum and C. albicans were inhibited at all light doses and curcumin concentrations, while inactivation of A. niger, A. flavus P. griseofulvum, P. chrysogenum and Z. bailii were highly significant (P<0.001) reduced by 99%, 88.9%, 78%, 99.7% and 99.2% respectively. On the surface of agar plates, spores/cells exposed to a light dose of 360J/cm2 sprayed with curcumin at 800µM showed complete inhibition for A. niger, F. oxysporum, C. albicans and Z. bailii, while A. flavus P. griseofulvum, and P. chrysogenum reduced by 75%, 80.4% and 88.5% respectively. Soaking spores/cells with curcumin solution prior to irradiation did not have a significant effect on the percentage reduction. These observations suggest that a novel photosensitization mediated curcumin treatment is effective against fungal spores/cells and the variation of percentage reduction was dependent on curcumin concentration, light dosage and fungal species.

Optimizing Prednisolone Loading into Distiller's Dried Grain Kafirin Microparticles, and In vitro Release for Oral Delivery.

Kafirin microparticles have potential as colon-targeted delivery systems because of their ability to protect encapsulated material from digestive processes of the upper gastrointestinal tract (GIT). The aim was to optimize prednisolone loading into kafirin microparticles, and investigate their potential as an oral delivery system. Response surface methodology (RSM) was used to predict the optimal formulation of prednisolone loaded microparticles. Prednisolone release from the microparticles was measured in simulated conditions of the GIT. The RSM models were inadequate for predicting the relationship between starting quantities of kafirin and prednisolone, and prednisolone loading into microparticles. Compared to prednisolone released in the simulated gastric and small intestinal conditions, no additional drug release was observed in simulated colonic conditions. Hence, more insight into factors affecting drug loading into kafirin microparticles is required to improve the robustness of the RSM model. This present method of formulating prednisolone-loaded kafirin microparticles is unlikely to offer clinical benefits over commercially available dosage forms. Nevertheless, the overall amount of prednisolone released from the kafirin microparticles in conditions simulating the human GIT demonstrates their ability to prevent the release of entrapped core material. Further work developing the formulation methods may result in a delivery system that targets the lower GIT.

Physico-chemical characteristics and fungal profile of four Saudi fresh date (Phoenix dactylifera L.) cultivars.

Physico-chemical and microbial analyses of four commercial fresh date cultivars (Sukari, Barhi, Khalas and Rothana) grown in Saudi Arabia were evaluated. Colorimetric assay indicated that Sukari had the highest total sugar content of 13.21g/100gFW while the lowest was in Rothana with 7.96g/100gFW. Total phenolic content (TPC) ranged from 76.74 to 122.20mgGAE/100gFW in Barhi and Rothana respectively, whereas antioxidant activity was highest in Sukari (105.99µgGAE/gFW) and lowest in Khalas (90.81µgGAE/gFW). The dominant fungal genera were Aspergillus sp., Rhizopus sp., Penicillium sp. and Sarocladium sp., occurring at 37, 18, 13 and 12% respectively. The highest fungal occurrence was in Barhi (30%) followed by Sukari (29%), Khalas (26%) and Rothana (15%). The TPC had a negative correlation with fungal occurrence whilst the total sugars had a positive correlation.

Betalain rich functional extract with reduced salts and nitrate content from red beetroot (Beta vulgaris L.) using membrane separation technology.

An initial laboratory-scale evaluation of separation characteristics of membranes with nominal molecular weight cut-offs (NMWCO) ranging from 30kD down to 0.5kD indicated effective separation of betalains in the 0.5kD region. Subsequent pilot-level trials using 1kD, loose reverse osmosis (LRO) and reverse osmosis (RO) spiral-wound membranes showed LRO membrane to be very efficient with up to 96% salt and 47% other dissolved solids removed while retaining majority of the pigment (∼98%) in the betalain rich extract (BRE). The total betalain content in the BRE increased up to 46%, the highest recovery reported so far at pilot scale level. Interestingly, more than 95% of the nitrates were removed from the BRE after the three diafiltrations. These studies indicate that membrane technology is the most efficient technique to produce BRE with highly reduced amounts of salts and nitrate content.