Effect of sequential pretreatment combinations on the composition and enzymatic hydrolysis of hazelnut shells.
Hazelnut shells, a high lignin containing biomass, were subjected to individual and sequential liquid hot water (LHW), alkaline (AP) and dilute acid pretreatments (DAP). Among the single pretreatments, LHW demonstrated the highest cellulose recovery of 98.1%, DAP resulted in the highest hemicellulose solubilization of 56.0%, and AP of the highest lignin removal of 49.6%. Employing two-step pretreatment on hazelnut shells, in general, demonstrated an enhanced action of the second pretreatment; therefore, the sequence of the pretreatment methods had a significant impact on both substrate characteristics and enzymatic hydrolysis efficiency of biomass. In terms of delignification, AP-LHW achieved 60.7% lignin removal, while LHW-DAP showed the highest hemicellulose removal of 93.8% and DAP-LHW resulted in the highest cellulose recovery of 94.0%. Structural properties of raw and pretreated hazelnut shells were observed by FTIR. The maximum glucose recovery of 54.9% was observed in DAP-LHW pretreated samples. For this pretreatment combination, almost 1.8 MJ total energy was required to recover 10.2 g glucose. The findings indicated that complete removal of the physical barrier of lignin and hemicellulose might not be essential; partial relocation of lignin and alteration of cellulose structure may also be efficient in increasing the sugar recovery from the lignocellulosic biomass.
Analysis and optimisation of a novel ‘almond-refinery’concept: Simultaneous production of biofuels and value-added chemicals by hydrothermal treatment of almond hulls.
For the first time, this work investigates the achievability of developing a biorefinery concept around almond hulls by hydrothermal treatment (HTT), thoroughly scrutinising the influence of the temperature (200-300 °C), pressure (100-180 bar), time (20-180 min) and solid loading (5-25 wt%). This process allowed the conversion of almond hulls into four main products: gas (2-13%), bio-oil (2-12%), aqueous (4-69%) and hydro-char (17-89%). The gas consisted of a mix of H2, CO2, CO and CH4 with a LHV fluctuating from 1 to 13 MJ/m3 STP. The bio-oil comprised a mixture of alkanes, aldehydes, ketones, phenols, furans, benzenes and nitrogen compounds with a HHV between 21 and 31 MJ/kg. The solid product resembled an energetic hydro-char material (HHV 21-31 MJ/kg), while the aqueous effluent comprised a mixture of value-added chemicals, including saccharides and small oxygenated compounds. The production of biofuels can be maximised at 256 °C and 100 bar, using a 5 wt% solid loading for 157 min, conditions at which 43% of the original feedstock can be converted into an elevated energy-filled bio-oil (11% yield, 30 MJ/kg), along with a high energetic hydro-char (32% yield, 29 MJ/kg). Regarding value-added chemicals, up to 10% of the almond hulls can be converted into a bio-oil with a high proportion (45%) of phenolic species at 250 °C and 144 bar with a solid loading of 5 wt% for 167 min. In comparison, a sugar-rich (81 C-wt%) solution can be produced in high yield (54%), by treating a 24 wt% suspension at 252 °C and 180 bar for 153 min. Therefore, the versatility, novelty and intrinsic green and holistic nature of this 'almond-refinery' concept exemplify a landmark achievement in future energy and chemicals production from biomass, which might help render the complete bio-refinery for almond hulls more cost-effectively and ecologically feasible.
Fe3O4 and Iminodiacetic acid modified peanut husk as a novel adsorbent for the uptake of Cu (II) and Pb (II) in aqueous solution: Characterization, equilibrium and kinetic study.
The presence of higher concentrations of heavy metals in water affects its quality with a concomitant adverse effect on its users thus their removal is paramount. A novel adsorbent, PN-Fe3O4-IDA derived from the chemical modification of peanut husk (a low-cost agricultural biomass produced in significant quantities globally) using magnetic nanoparticles (Fe3O4) and iminodiacetic acid was utilized for the remediation of heavy metals in aqueous solution. Analytical techniques vis-à-vis the Fourier-Transform Infrared, Scanning Electron Microscope, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy and X-ray Diffraction were applied for the characterization of PN-Fe3O4-IDA. Results from the characterization studies showed that PN-Fe3O4-IDA possessed a mesoporous structure, a heterogeneous surface and functional groups such as carboxylic acid and a tertiary nitrogen atom which enhanced its adsorption capacities as well as magnetic properties which ensured its easy removal from the solution using a magnet. The maximum uptake of Pb and Cu onto PN-Fe3O4-IDA was 0.36 and 0.75 mmol g-1 (at 318 K) respectively with the chemisorption process being the major reaction pathway for the processes. The synthesized adsorbent exhibits significant adsorption capacity for the selected pollutants as well as some unique features which promotes its use as an adsorbent for wastewater remediation processes.
Kinetics characteristics and microwave reduction behavior of walnut shell-pyrolusite blends.
Combining biomass pyrolysis with microwave heating technologies provides a novel and efficient approach for low-grade pyrolusite reduction. The microwave reduction behavior and pyrolysis kinetic characteristics of walnut shell-pyrolusite blends were explored. Results indicated the optimal reduction parameters were: reduction temperature of 650 °C, holding time of 30 min, Mbio/More of 1.8:10, and microwave power of 1200 W. The co-pyrolysis characteristics of the blends included four stages: dehydration, pre-pyrolysis, intense pyrolysis and reduction, and slow pyrolysis and reduction. Fitting analysis based on Coats-Redfern method revealed that chemical reaction was the control step of the process of reducing pyrolusite by biomass, which the finding matched to the isothermal kinetic analysis results determined through unreacted shrinking nuclear model. The activation energies and pre-exponential factors were determined at 5.62 kJ·mol-1-16.69 kJ·mol-1 and 0.0426 min-1-0.515 min-1. The work provides sound references for promoting the industrial application of the combined method on minerals reduction.
Recovery of Bioactive Compounds from Hazelnuts and Walnuts Shells: Quantitative–Qualitative Analysis and Chromatographic Purification.
Hazelnut (HS) and walnut (WS) shells, an abundant by-product of the processing industries of these edible nuts, are traditionally considered as a low-value waste. However, they are a source of valuable compounds with an interesting chemical profile for the chemical and pharmaceutical sectors. In this study, the lipophilic and hydrophilic extracts present in HS and WS were quantified and identified, then the polar fractions were chromatographically separated, and their antioxidant capacity was studied. The experimental work includes the isolation of crude lipophilic and hydrophilic extracts by an accelerated extraction process, chromatographic analysis (gas chromatography-flame ionization (GC-FID), GC-mass spectroscopy (GC-MS), high-performance size-exclusion chromatography (HPSEC), thin-layer chromatography (TLC)), and quantification of the components. In addition, a thorough compositional characterization of the subgroups obtained by flash chromatography and their antioxidant capacity was carried out. The gravimetric concentrations showed different lipophilic/hydrophilic ratios (0.70 for HS and 0.23 for WS), indicating a higher proportion of polar compounds in WS than in HS. Moreover, the lipophilic extracts were principally composed of short-chain fatty acids (stearic, palmitic, and oleic acid), triglycerides, and sterols. The polar fractions were screened by thin-layer chromatography and then separated by flash chromatography, obtaining fractions free of fatty acids and sugar derivatives (97:3 in HS and 95:5 in WS), and mixtures richer in phenolic compounds and flavonoids such as guaiacyl derivatives, quercetin, pinobanksin, and catechin. The most polar fractions presented a higher antioxidant capacity than that of the crude extracts.
Field efficacy of two atoxigenic biocontrol products for mitigation of aflatoxin contamination in maize and groundnut in Ghana.
Biological control is one of the recommended methods for aflatoxin mitigation. Biocontrol products must be developed, and their efficacy demonstrated before widespread use. Efficacy of two aflatoxin biocontrol products, Aflasafe GH01 and Aflasafe GH02, were evaluated in 800 maize and groundnut farmers’ fields during 2015 and 2016 in the Ashanti, Brong Ahafo, Northern, Upper East, and Upper West regions of Ghana. Both products were developed after an extensive examination of fungi associated with maize and groundnut in Ghana. Each product contains as active ingredient fungi four Aspergillus flavus isolates belonging to atoxigenic African Aspergillus Vegetative Compatibility Groups (AAVs) widely distributed across Ghana. An untreated field was maintained for each treated field to determine product efficacy. Proportions of atoxigenic AAVs composing each product were assessed in soils before product application, and soils and grains at harvest. Significant (P < 0.05) displacement of toxigenic fungi occurred in both crops during both years, in all five regions. Biocontrol-treated crops consistently had significantly (P < 0.05) less aflatoxins (range = 76% to 100% less; average = 99% less) than untreated crops. Results indicate that both biocontrol products are highly efficient, cost-effective, environmentally safe tools for aflatoxin mitigation. Most crops from treated fields could have been sold in both local and international food and feed premium markets. Adoption and use of biocontrol products have the potential to improve the health of Ghanaians, and both income and trade opportunities of farmers, aggregators, distributors, and traders.
Impact of climate change on navel Orangeworm, a Major Pest of tree nuts in California.
California's agricultural sector is the highest valued agricultural sector in the United States. It is also a global leader in the production of various specialty crops, including three major tree nuts - almond, walnut, and pistachio. These three nut crops accounted for approximately 16% of the state's total agricultural economy. Current and future changes in climate pose many challenges in agriculture and impacts related to increased pest pressure in agriculture due to elevated temperatures are significant. The navel orangeworm, Amyelois transitella (Walker), is the most challenging pest of tree nuts in California and often cause a significant economic loss despite the careful implementation of multiple pest control tactics. Temperature variations can directly affect the developmental rates, behavior, and overall population dynamics of this pest, and it is critically important to understand these dynamics with respect to climate change. The objective of this study was to quantify changes in the timing and number of navel orangeworm generations in almonds, walnuts, and pistachios for the entire Central Valley of California using projections from ten general circulation models (GCMs) under two emission scenarios. The results suggest that navel orangeworm is likely to complete its life cycle much faster under climate change due to projected temperature increases. The results also suggest that under future climate change, navel orangeworm can complete one additional generation within the growing season and likely going to pose significant risks to these major nut industries in the future. Quantifying navel orangeworm generations and assessing risks to tree nuts under climate change can help facilitate and strategize integrated pest management (IPM) practices to the sustainability of the production systems by minimizing risks.
Quantification of the aflatoxin biocontrol strain Aspergillus flavus AF36 in soil, and nuts and leaves of pistachio by real-time PCR.
The species Aspergillus flavus and A. parasiticus are commonly found in the soils of nut-growing areas in California. Several isolates can produce aflatoxins that occasionally contaminate nut kernels conditioning their sale. The strain AF36 of A. flavus, which does not produce aflatoxins, is registered as a biocontrol agent for use in almond, pistachio, and fig crops in California. After application in the orchards, AF36 displaces aflatoxin-producing Aspergillus spp. and thus reduces aflatoxin contamination. Vegetative compatibility assays (VCA) have traditionally been used to track AF36 in soils and crops where it has been applied. However, VCA is labor-intensive and time-consuming. Here, we developed a quantitative real-time PCR (qPCR) protocol to quantify proportions of AF36 accurately and efficiently in different substrates. Specific primers to target AF36 and toxigenic strains of A. flavus and A. parasiticus were designed based on sequence of aflC, a gene essential for aflatoxin biosynthesis. Standard curves were generated to calculate proportions of AF36 based on threshold values (Cq). Verification assays using pure DNA and conidial suspension mixtures demonstrated a significant relationship by regression analysis between known and qPCR-measured AF36 proportions in DNA (R2 = 0.974; P < 0.001) and conidia mixtures (R2 = 0.950; P < 0.001). The tests conducted by qPCR in pistachio leaves, nuts, and soil samples demonstrated the usefulness of the qPCR method to precisely quantify proportions of AF36 in diverse substrates, ensuring important time and cost savings. The outputs of the current study will serve to design better aflatoxin management strategies for pistachio and other crops.
Hyperspectral Shortwave Infrared Image Analysis for Detection of Adulterants in Almond Powder with One-Class Classification Method.
The widely used techniques for analyzing the quality of powdered food products focus on targeted detection with a low-throughput screening of samples. Owing to potentially significant health threats and large-scale adulterations, food regulatory agencies and industries require rapid and non-destructive analytical techniques for the detection of unexpected compounds present in products. Accordingly, shortwave-infrared hyperspectral imaging (SWIR-HSI) for high throughput authenticity analysis of almond powder was investigated in this study. Two different varieties of almond powder, adulterated with apricot and peanut powder at different concentrations, were imaged using the SWIR-HSI system. A one-class classifier technique, known as data-driven soft independent modeling of class analogy (DD-SIMCA), was used on collected data sets of pure and adulterated samples. A partial least square regression (PLSR) model was further developed to predict adulterant concentrations in almond powder. Classification results from DD-SIMCA yielded 100% sensitivity and 89-100% specificity for different validation sets of adulterated samples. The results obtained from the PLSR analysis yielded a high determination coefficient (R2) and low error values (<1%) for each variety of almond powder adulterated with apricot; however, a relatively higher error rates of 2.5% and 4.4% for the two varieties of almond powder adulterated with peanut powder, which indicates the performance of quantitative analysis model could vary with sample condition, such as variety, originality, etc. PLSR-based concentration mapped images visually characterized the adulterant (apricot) concentration in the almond powder. These results demonstrate that the SWIR-HSI technique combined with the one-class classifier DD-SIMCA can be used effectively for a high-throughput quality screening of almond powder regarding potential adulteration.
Characterization of peanut seed oil of selected varieties and its application in the cereal-based product.
Peanut (Arachis hypogaea) is an important oilseed crop of the world. Peanut seed oil (PSO) contains linolenic acid, oleic acid, also a good source of omega-6 fatty acids and omega-3 fatty acids. It contains an abundant amount of vitamin E which also act as an antioxidant. The research work was carried out to estimate the suitability of utilization of peanut oil from different available peanut varieties, i.e., Bari 2001, Bari 2011 in cereal-based products. The main objective of the study is the characterization of peanut seed oil acquired from Bari 2001 and 2011 variety, and explored its application in cookies and shelf life of the product. The purpose of the study is to determine the oil contents and characterization, its application in cookies and shelf life of the product. The data thus collected was analyzed by applying standard statistical procedures. Peroxide, saponification, and free fatty acids in Bari 2001 and Bari 2011 were 1.51 ± 0.09 meq O2/kg and 1.47 ± 0.07 meq O2/kg, 195.81 ± 2.47 mgKOH/g and 191.60 ± 2.66 mgKOH/g and 0.96 ± 0.07% and 0.91 ± 0.04% respectively. Cookies were prepared by incorporating PSO oil (Bari 2011) at concentrations of 5% (FC1), 10% (FC2), 15% (FC3), 20% (FC4), 25% (FC5) and along with control (FC0). Storage study (60 days) assessed the quality, sensory evaluation and oxidative stability of products in order of most suitable to least accepted as FC3 > FC4 > FC5 > FC1 > FC2 > FC0. The cookies produced by 15% replacement peanut seed oil resulted in an acceptable product.