Macadamia oil-based oleogels as cocoa butter alternatives: Physical properties, oxidative stability, lipolysis, and application.
In this study, macadamia oil-based oleogels were prepared using monoglyceride stearate (MG) as a gelator with a low critical gelation concentration (3.0 wt%). The physical properties of the oleogels were evaluated by polarized light microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, texture and rheological analysis. And the lipid digestion and oxidative stability of the macadamia oil were determined by pH titration and accelerated oxidation test, respectively. The results showed that the hardness, oil binding capacity, and thermal stability of the oleogels increased with increasing MG concentration, which was attributed to the formation of a network of MG crystals held together by van der Waals interactions and hydrogen bonds. Rheological analysis indicated that all the oleogels exhibited a thermally reversible solid-to-liquid transition and viscoelastic behavior at ambient temperatures. Moreover, the formation of oleogels increased fatty acid release during in vitro lipid digestion and improved the oxidative stability of the macadamia oil. In addition, the potential application of these oleogels as replacements for saturated fats in foods was demonstrated by creating a chocolate product where the cocoa butter was replaced with macadamia oil-based oleogels with a high degree of unsaturation. These results can provide guidance for the preparation of macadamia oil-based oleogels, which may increase their application in foods. https://doi.org/10.1016/j.foodres.2023.113098
The relative dominance of surface oxygen content over pore properties in controlling adsorption and retrograde behavior of gaseous toluene over microporous carbon.
The performance of activated carbon (AC) derived from macadamia nut shells (product code of Procarb-900: namely, AC-P) has been investigated using gaseous toluene as the target pollutant. The powder AC-P with high-microporosity (96 %) and oxygen content (5.62 %) exhibited very high adsorption capacity (214 mg·g-1) and partition coefficient (PC: 25 mol·kg-1·Pa-1) against 100 ppm (10 Pa) toluene at 99 % breakthrough levels (1 atm dry N2). The factors governing toluene adsorption were explored with respect to the key variables such as surface functional groups, pore size distribution, sorbent bed mass (50, 100, and 150 mg), and particle size (i.e., 0.212-0.6 mm (powder AC: PAC)) vs. 0.6-2.36 mm (granular AC: GAC)). Accordingly, the adsorption process was physical, mainly due to the non-polar interactions (i.e., π-π interactions) between the adsorbent and adsorbate molecules. The high affinity of AC-P at low breakthrough levels was obtained through a combination of smaller particle size (PAC) and larger adsorbent mass (i.e., 150 mg) with the appearance of a very pronounced retrograde phenomenon (e.g., at <1 % breakthrough level). As such, toluene adsorption appeared to be affected more sensitively by particle size and adsorbent mass (especially at low breakthrough levels) than by high microporosity. Most importantly, the oxygen content of AC emerges as one of the key factors governing the maximum capacity, as the changes in pore volume are not crucial to explain the observed adsorption patterns of toluene.
https://doi.org/10.1016/j.scitotenv.2023.167308
Aflatoxins and Ochratoxin A in dried fruits from Morocco: Monitoring, regulatory aspects, and exposure assessment.
The present study aims to investigate the presence of Aflatoxins (AF) in 180 samples dried fruits and Ochratoxin A (OTA) in 210 samples dried fruits and grape juices collected in Morocco. Mycotoxins were analyzed by high performance liquid chromatography (HPLC) coupled to fluorescence detection and immunoaffinity columns (IAC) cleanup. Contamination levels were compared with the maximum regulatory limits (MRL) recently adopted in the country, and mycotoxin exposure of adult consumers was assessed. Results showed that 13.8% of samples were contaminated with AF, with incidences of 23.3, 23.3, 20, 13.8, and 3.3%, in raisins, figs, nuts, peanuts and pistachio, respectively. There were 12 samples (6.6%) that exceeded the MRL of 2-12 ng/g set for aflatoxin B1 (AFB1). While OTA was detected in 17.1% of samples, with incidences of 3.3, 3.3, 30, 30, and 53.3% in walnuts, pistachios, peanuts, raisins and figs, respectively, and a maximum value of 99.1 in dried raisins, that exceeded the MRL (10 ng/g) set for OTA. The co-occurrence of OTA and AF was observed in 4.7% of total samples. Dietary intake showed that the OTA exposure level was lower than safety guidelines set by The Joint FAO/WHO Expert Committee on Food Additives (JECFA) at 100 ng/kg b.w./week. https://doi.org/10.1016/j.yrtph.2023.105503
Genetic diversity of Salmonella enterica isolated over 13 years from raw California almonds and from an almond orchard
A comparative genomic analysis was conducted for 171 Salmonella isolates recovered from raw inshell almonds and raw almond kernels between 2001 and 2013 and for 30 Salmonella Enteritidis phage type (PT) 30 isolates recovered between 2001 and 2006 from a 2001 salmonellosis outbreak-associated almond orchard. Whole genome sequencing was used to measure the genetic distance among isolates by single nucleotide polymorphism (SNP) analyses and to predict the presence of plasmid DNA and of antimicrobial resistance (AMR) and virulence genes. Isolates were classified by serovars with Parsnp, a fast core-genome multi aligner, before being analyzed with the CFSAN SNP Pipeline (U.S. Food and Drug Administration Center for Food Safety and Applied Nutrition). Genetically similar (≤18 SNPs) Salmonella isolates were identified among several serovars isolated years apart. Almond isolates of Salmonella Montevideo (2001 to 2013) and Salmonella Newport (2003 to 2010) differed by ≤9 SNPs. Salmonella Enteritidis PT 30 isolated between 2001 and 2013 from survey, orchard, outbreak, and clinical samples differed by ≤18 SNPs. One to seven plasmids were found in 106 (62%) of the Salmonella isolates. Of the 27 plasmid families that were identified, IncFII and IncFIB plasmids were the most predominant. AMR genes were identified in 16 (9%) of the survey isolates and were plasmid encoded in 11 of 16 cases; 12 isolates (7%) had putative resistance to at least one antibiotic in three or more drug classes. A total of 303 virulence genes were detected among the assembled genomes; a plasmid that harbored a combination of pef, rck, and spv virulence genes was identified in 23% of the isolates. These data provide evidence of long-term survival (years) of Salmonella in agricultural environments. https://doi.org/10.1371/journal.pone.0291109
Walnut Flour as an Ingredient for Producing Low-Carbohydrate Bread: Physicochemical, Sensory, and Spectroscopic Characteristics
Walnut flour (WF) is a nutrient-rich source that can be used as an alternative for individuals on a gluten-free diet. This study aimed to assess the physical, chemical, and sensory changes in low-carbohydrate bread when supplemented with WF. Molecular-level changes were also examined using ATR-FTIR spectra. The bread recipe, containing buckwheat and flaxseed, was enriched with WF at levels ranging from 5% to 20%. The addition of WF resulted in increased loaf volume and decreased baking loss. Enriched bread samples showed higher protein content, while fat and available carbohydrate content decreased. Additionally, WF incorporation led to a decrease in crumb brightness and an increase in redness (from 23.1 to 25.4) and yellowness (from 23.8 to 26.7). WF also increased crumb hardness and chewiness. Moreover, the tested additives primarily influenced the intensity of FTIR spectra, indicating changes in protein, carbohydrate, and fat content, with increased band intensity observed in the protein region. We particularly recommend bread with a WF content of 15%. This type of bread is characterized by high consumer acceptance. Furthermore, compared to bread without the addition of WF, it has a higher content of phenolic compounds, protein, and fat by approximately 40%, 8%, and 4%, respectively. The antioxidant activity of this bread, determined using the ABTS and DPPH methods, is also significantly higher compared to the control bread. https://doi.org/10.3390/foods12173320
Whole genome analysis of Bacillus amyloliquefaciens TA-1, a promising biocontrol agent against Cercospora arachidicola pathogen of early leaf spot in Arachis hypogaea L
Background: Early leaf spot disease, caused by Cercospora arachidicola, is a devastating peanut disease that has severely impacted peanut production and quality. Chemical fungicides pollute the environment; however, Bacillus bacteria can be used as an environmentally friendly alternative to chemical fungicides. To understand the novel bacterial strain and unravel its molecular mechanism, De novo whole-genome sequencing emerges as a rapid and efficient omics approach. Results: In the current study, we identified an antagonistic strain, Bacillus amyloliquefaciens TA-1. In-vitro assay showed that the TA-1 strain was a strong antagonist against C. arachidicola, with an inhibition zone of 88.9 mm. In a greenhouse assay, results showed that the TA-1 strain had a significant biocontrol effect of 95% on peanut early leaf spot disease. De novo whole-genome sequencing analysis, shows that strain TA-1 has a single circular chromosome with 4172 protein-coding genes and a 45.91% guanine and cytosine (GC) content. Gene function was annotated using non-redundant proteins from the National Center for Biotechnology Information (NCBI), Swiss-Prot, the Kyoto Encyclopedia of Genes and Genomes (KEGG), clusters of orthologous groups of proteins, gene ontology, pathogen-host interactions, and carbohydrate-active enZYmes. antiSMASH analysis predicted that strain TA-1 can produce the secondary metabolites siderophore, tailcyclized peptide, myxochelin, bacillibactin, paenibactin, myxochelin, griseobactin, benarthin, tailcyclized, and samylocyclicin. Conclusion: The strain TA-1 had a significant biological control effect against peanut early leaf spot disease in-vitro and in greenhouse assays. Whole genome analysis revealed that, TA-1 strain belongs to B. amyloliquefaciens and could produce the antifungal secondary metabolites. https://doi.org/10.1186/s12870-023-04423-4
Efficacy of the biocontrol agent Trichoderma hamatum against Lasiodiplodia theobromae on macadamia
Macadamia (Macadamia integrifolia) trees are an important source of revenue in rainforest ecosystems. Their nuts are rich in vitamins, minerals, fiber, antioxidants, and monounsaturated oils. The fungus Lasiodiplodia theobromae, however, is a major disease problem, causing kernel rot and other disease symptoms. In the present study, a dual confrontation assay was used to evaluate the inhibitory effect of an endophytic strain of Trichoderma hamatum C9 from macadamia root against L. theobromae. Volatiles and cell-free culture filtrate of T. hamatum were also used to assess their antifungal activity against L. theobromae. Results suggested that T. hamatum exhibited a significant inhibitory effect against L. theobromae in vitro. Further results of a biocontrol assay indicated that a spray treatment of T. hamatum conidial suspension significantly decreased the size of lesions caused by artificially inoculated L. theobromae on macadamia leaves, as well as the disease index in young trees inoculated with L. theobromae, relative to sterile water controls. Collectively, our findings indicate that T. hamatum C9 represents a potential biocontrol agent that can be used to manage L. theobromae on macadamia. https://doi.org/10.3389/fmicb.2022.994422
Computer vision-assisted smartphone microscope imaging digital immunosensor based on click chemistry-mediated microsphere counting technology for the detection of aflatoxin B1 in peanuts
Aflatoxin B1 is a carcinogenic contaminant in food or feed, and it poses a serious health risk to humans. Herein, a computer vision-assisted smartphone microscope imaging digital (SMID) immunosensor based on the click chemistry-mediated microsphere counting technology was designed for the detection of aflatoxin B1 in peanuts. In this SMID immunosensor, the modified polystyrene (PS) microspheres were used as the signal probes and were recorded by a smartphone microscopic imaging system after immunoreaction and click chemistry reaction. The number of PS probes is adjusted by aflatoxin B1. The customized computer vision procedure was used to efficiently identify and count the obtained PS probes. This SMID immunosensor enables sensitive detection of aflatoxin B1 with a linear range from 0.001 ng/mL to 500 ng/mL, providing a simple, sensitive, and portable tool for food safety supervision. https://doi.org/10.1016/j.aca.2023.341687
Clinically and industrially relevant incurred reference materials to improve analysis of food allergens, milk, egg, almond, hazelnut and walnut
Measurement of food allergen protein concentrations against thresholds can improve allergen risk management and precautionary allergen labelling. Such measurement suffers well known problems which could be ameliorated by well characterised reference materials (RMs) providing meaningful information for risk assessors. We investigated the preparation and characterisation of the first consensus informed industrially and clinically relevant multi-allergen matrix RM kit for five priority allergens. It is a medium analytical difficulty processed food chocolate paste matrix (a) devoid of allergens, and (b) incurred with five allergens at the clinically relevant concentration of 10 mg kg-1 expressed as protein. The allergen raw materials: hens' egg white powder, skimmed cows' milk powder, almond powder (full fat), hazelnut powder (partially defatted), and walnut powder (partially defatted), are also available as RMs. The preparation, gravimetric traceability to the SI, homogeneity, and stability were found to be fit-for-purpose and the RMs are now available to the analytical community. https://doi.org/10.1016/j.foodchem.2023.137391
Assessing the Impact of Roasting Temperatures on Biochemical and Sensory Quality of Macadamia Nuts (Macadamia integrifolia)
Depending on the temperature regime used during roasting, the biochemical and sensory characteristics of macadamia nuts can change. 'A4' and 'Beaumont' were used as model cultivars to examine how roasting temperatures affected the chemical and sensory quality of macadamia nuts. Using a hot air oven dryer, macadamia kernels were roasted at 50, 75, 100, 125, and 150 °C for 15 min. The quantity of phenols, flavonoids, and antioxidants in kernels roasted at 50, 75, and 100 °C was significant (p < 0.001); however, these kernels also had high levels of moisture content, oxidation-sensitive unsaturated fatty acids (UFAs), and peroxide value (PV), and poor sensory quality. Low moisture content, flavonoids, phenols, antioxidants, fatty acid (FA) compositions, high PV, and poor sensory quality-i.e., excessive browning, an exceptionally crunchy texture, and a bitter flavor-were all characteristics of kernels roasted at 150 °C. With a perfect crispy texture, a rich brown color, and a strong nutty flavor, kernels roasted at 125 °C had lower PV; higher oxidation-resistant UFA compositions; considerable concentrations of flavonoids, phenols, and antioxidants; and good sensory quality. Therefore, 'A4' and 'Beaumont' kernels could be roasted at 125 °C for use in the industry to improve kernel quality and palatability. https://doi.org/10.3390/foods12112116