Determination of nutrients in sugarcane juice using slurry sampling and detection by ICP OES

Removal of phenolic compounds from sugarcane syrup and impact on Saccharomyces cerevisiae fermentation for β-farnesene production

This work aimed to study for the first time the effects of phenolic compounds from sugarcane syrup on Saccharomyces cerevisiae β-farnesene fermentation by removing them from this feedstock. Syrup purification was optimized through a central composite design using five types of activated charcoal: three contact times (1-24 h) and three adsorbent concentrations (10-150 g L-1 ). The optimal purification condition-charcoal pellets at 115 g L-1 and contact time of 12.5 h-led to 96.7% of phenolic compounds removal and 43.7% of syrup recovery. The effects of reducing phenolic content from approximately 7.0-0.3 mg L-1 in sugarcane syrup on yeast fermentation varied with the scale. An increase in biomolecule productivity was only observed in shake-flasks (11%) and in biomass productivity only in the 2 L bioreactor (12%). Thus, phenolic compounds from sugarcane syrup do not influence β-farnesene production at a large scale under the conditions tested.

Biocontrol ability of Bacillus velezensis T9 against Apiospora arundinis causing Apiospora mold on sugarcane

Sugarcane (Saccharum officinarum L.) may be infected with Apiospora, which can produce the toxin 3-nitropropionic acid (3-NPA) during improper transportation and storage. The consumption of sugarcane that contains 3-NPA can lead to food poisoning. Therefore, this study sought to explore a novel biocontrol agent to prevent and control Apiospora mold. Bacteria were isolated from the soil of healthy sugarcane and identified as Bacillus velezensis T9 through colony morphological, physiological and biochemical characterization and molecular identification. The inhibitory effect of B. velezensis T9 on Apiospora mold on sugarcane was analyzed. Assays of the cell suspension of strain T9 and its cell-free supernatant showed that T9 had significant in vitro antifungal activities against Apiospora arundinis and thus, would be a likely antagonist. Scanning electron microscopy and transmission electron microscopy showed that treatment with T9 significantly distorted the A. arundinis mycelia, perforated the membrane, contracted the vesicles, and decomposed most organelles into irregular fragments. A re-isolation experiment demonstrates the ability of T9 to colonize the sugarcane stems and survive in them. This strain can produce volatile organic compounds (VOCs) that are remarkably strong inhibitors, and it can also form biofilms. Additionally, the cell-free supernatant significantly reduced the ability of A. arundinis to produce 3-NPA and completely inhibited its production at 10%. Therefore, strain T9 is effective at controlling A. arundinis and has the potential for further development as a fungal prevention agent for agricultural products.

In Situ Detection of Trace Heavy Metal Cu in Water by Atomic Emission Spectrometry of Nebulized Discharge Plasma at Atmospheric Pressure

The in situ detection of trace heavy metal is very important for human health and environmental protection. In this paper, a novel and stable nebulized discharge excited by an alternating current (AC) power supply at atmospheric pressure is employed to detect the trace metal copper by atomic emission spectrometry. Different from the previous experiments in which a conductive object was wrapped around a pneumatic nebulizer directly as a discharge electrode. Plasma is generated near needle electrodes and aerosol is introduced from above the electrode gap by a pneumatic nebulizer, which avoid damage to the fragile device. The effects of applied voltage, gas flow rate, pH value of liquid, and concentration of organic addition agents on the emission intensity of Cu I (3d104p-3d104s, 324.75 nm) are investigated for the purpose of optimizing the experiment conditions. For studying the discharge characteristics and understanding the mechanisms of metal atomic excitation, the waveforms of applied voltage and discharge current are measured, and the vibrational and rotational temperature are calculated by the spectra of N2 (C3∏u-B3∏g, Δυ = −2). In addition, gas temperature evolution of nebulized discharge is acquired and it is found that the emission intensity of Cu I (3d104p-3d104s, 324.75 nm) can be affected by applied voltage, gas flow rate, pH value of liquid, and concentration of organic addition agents. An optimized experimental condition of nebulized discharge for Cu detection is 3.59 of the pH, 5.6 kV of applied voltage, 1.68 L/min of Ar flow rate, and 2% of the ethanol. Under this condition, the limit of detection (LOD) of Cu can reach up to 0.083 mg/L.

Development of an Immunoassay for the Detection of Copper Residues in Pork Tissues

The presence of high concentrations of copper (Cu) residues in pork is highly concerning and therefore, this study was designed to develop a high-throughput immunoassay for the detection of such residues in edible pork tissues. The Cu content in the pork samples after digestion with HNO₃ and H₂O₂ was measured using a monoclonal antibody (mAb) against a Cu (II)–ethylenediaminetetraacetic acid (EDTA) complex. The resulting solution was neutralized using NaOH at pH 7 and the free metal ions in the solution were chelated with EDTA for the immunoassay detection. An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) method was developed for Cu ion analysis. The half maximal inhibitory concentration of the mAb against Cu (II)–EDTA was 5.36 ng/mL, the linear detection range varied between 1.30 and 27.0 ng/mL, the limit of detection (LOD) was 0.43 μg/kg, and the limit of quantification (LOQ) was 1.42 μg/kg. The performances of the immunoassay were evaluated using fortified pig serum, liver, and pork samples and had a recovery rate of 94.53–102.24%. Importantly, the proposed immunoassay was compared with inductively coupled plasma mass spectroscopy (ICP-MS) to measure its performance. The detection correlation coefficients of the three types of samples (serum, pork, and liver) were 0.967, 0.976, and 0.983, respectively. Thirty pork samples and six pig liver samples were collected from local markets and Cu was detected with the proposed ic-ELISA. The Cu content was found to be 37.31~85.36 μg/kg in pork samples and 1.04–1.9 mg/kg in liver samples. Furthermore, we detected the Cu content in pigs with feed supplemented with tribasic copper chloride (TBCC) and copper sulfate (CS) (60, 110, and 210 mg/kg in feed). There was no significant difference in Cu accumulation in pork tissues between the TBCC and CS groups, while a remarkable Cu accumulation was found for the CS group in liver at 210 mg/kg, representing more than a two-fold higher level than seen in the TBCC group. Therefore, the proposed immunoassay was found to be robust and sensitive for the detection of Cu, providing a cost effective and practical tool for its detection in food and other complicated samples.

Chemometric tools in the optimization of a microwave-assisted digestion procedure for guarana-based drink samples and data analysis from elemental, caffeine, and epicatechin contents

In this work, a method was developed for the determination of Na, K, Ca, Mg, P, S, Fe, Zn, Mn, and Cu by ICP OES and caffeine and epicatechin by HPLC-DAD in industrialized guarana-based beverages. The acid digestion in microwave oven was optimized by constrained mixture design. The optimum volumes found for the reagents were 2.60 mL (HNO₃), 1.80 mL (H₂O₂), and 0.60 mL (HCl) for a final volume of 10 mL, resulting in a final digestate with residual acidity of 0.8 mol L^-1 and 9% for residual carbon content. The detection limits found for the studied elements were between 0.0010 and 0.050 mg L^-1. Precision (%RSD) was always below 6%. Accuracy was assessed by analyzing a certified reference material and addition and recovery tests. PCA and HCA were applied to caffeine, epicatechin and elemental concentrations aiming to evidence latent information.

Evaluation of slurry sampling preparation of enteral nutrition formulations for multielement determination using inductively coupled plasma optical emission spectrometry

An analytical procedure for the multielement determination in enteral nutrition formulations employing slurry sampling and inductively coupled plasma optical emission spectrometry (ICP OES) is proposed. A two-level full-factorial design was applied to assess the influence of the presence of stabilizing agents (HNO₃, Triton X-100 and ethanol) on the composition of the slurry. Multiple response was established as a dependent variable. The experimental conditions for the preparation of the slurry were: 2.0 mL of sample and 8.0 mL of 10% (v/v) HNO₃. The limits of detection (LOD) were 5; 9; and 10 µg L^-1 for Cu, Fe, Zn, respectively. For P, and K, the LOD were 8 and 24 mg L^-1, respectively. The method was applied for the analysis of three enteral nutrition formulation samples and the obtained concentrations ranges were (in mg L^-1): 0.41-0.43 (Cu), 2.0-2.9 (Fe), 1.7-3.1 (Zn), 682-1409 (K), and 217-344 (P).

Doehlert design in the optimization of procedures aiming food analysis - A review

In the present paper is presented a review on the application of Doehlert design in the optimization of some of the steps of analytical procedures aimed the analysis of food samples. The theoretical principles and the main characteristics of this type of design are described. In addition, the main advantages and limitations of Doehlert design over other designs (Central Composite Design and Box-Behnken) and its application in the area of food analysis are discussed. Finally, to illustrate its potential, some examples of Doehlert design application in other areas of food chemistry without the purpose of analytical determination will be briefly presented.

Electrospun nanofibrous membrane for filtration of coconut neera

Coconut neera is a nutritious natural drink that is rich in amino acids, polyphenols, vitamins, and minerals. Nevertheless, the inherent presence of yeast activates natural fermentation. To prevent the fermentation process, it is necessary to reduce the yeast load in fresh neera, at the earliest possible. In this research, an electrospun polycaprolactone nanofibrous membrane was used for the removal of yeast from coconut neera. Randomly oriented non-woven nanofibers were fabricated using the electrospinning process. The process conditions were optimized at 15 kV applied voltage, 8 cm distance between the spinneret needle and the collector plate, and 1.6 ml/h feed flow rate for the best nanofiber characteristics and high filtration efficiency. The optimized nanofibrous membrane for neera filtration had an average fiber diameter of 942 nm, average porosity of 73.26%, and a mean thickness of 150 µm. Results confirmed that the porosity of the membrane had a significant effect on the flow rate of permeate. The biochemical characteristics of neera filtrate were investigated. In comparison with fresh neera, the filtered counterpart had significant changes in titratable acidity, pH, and color. While no significant changes were observed in total soluble solids content, slight reductions were noted in the total polyphenolic content and minerals. Importantly, the neera filtrate obtained through the optimized nanofibrous membrane showed a 2 log-reduction in yeast load. The effective reusability of the membrane and stability of the nanofiber morphology at repeated usage was confirmed. This approach shows prospects for neera filtration while retaining nutrient content and can be extended to other natural extract applications.

Recent Techniques in Nutrient Analysis for Food Composition Database

Food composition database (FCD) provides the nutritional composition of foods. Reliable and up-to date FCD is important in many aspects of nutrition, dietetics, health, food science, biodiversity, plant breeding, food industry, trade and food regulation. FCD has been used extensively in nutrition labelling, nutritional analysis, research, regulation, national food and nutrition policy. The choice of method for the analysis of samples for FCD often depends on detection capability, along with ease of use, speed of analysis and low cost. Sample preparation is the most critical stage in analytical method development. Samples can be prepared using numerous techniques; however it should be applicable for a wide range of analytes and sample matrices. There are quite a number of significant improvements on sample preparation techniques in various food matrices for specific analytes highlighted in the literatures. Improvements on the technology used for the analysis of samples by specific instrumentation could provide an alternative to the analyst to choose for their laboratory requirement. This review provides the reader with an overview of recent techniques that can be used for sample preparation and instrumentation for food analysis which can provide wide options to the analysts in providing data to their FCD.

Simple and fast ultrasound-assisted method for mineral content and bioaccessibility study in infant formula by ICP OES

Infant formula (IF) constitutes the sole source of mineral intake for infants who are only fed IF. The assurance of the amount of minerals declared on the label and the mineral levels and their chemical forms present a major concern related to providing a good amount of nutrients for absorption by these children. Thus, the objectives of this study were: (i) to evaluate several sample preparation methods for minerals in IF; (ii) to validate an analytical method using an ultrasonic bath for simultaneous determination of the Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn contents in IF by ICP OES and (ii) to establish the optimum analytical conditions of the in vitro method to study the dialyzability of these minerals from IF. The ultrasound-assisted method was shown to conform to 'green chemistry principles', being simple, fast and low cost compared with reference methods. The results were similar to those obtained with reference methods (microwave-assisted acid digestion and dry ashing) with regard to selectivity, sensitivity and linearity (r2 > 0.999). The accuracy and the precision were verified using certified reference materials, with recoveries and coefficients of variation ranging from 91 to 105% and from 1.1 to 5.2%, respectively. For in vitro dialyzability, the conditions established in this study allowed including an overnight step between the gastric and gastrointestinal stages (accuracy and precision ranging from 81 to 108% and 0.4 to 6.3%, respectively), contributing to establishing an in vitro digestion method suitable for infant gastrointestinal conditions.

Determination of Phosphorus in Soil by ICP-OES Using an Improved Standard Addition Method

In this study, an improved standard addition method (ISAM) was developed for the determination of phosphorus in soil by ICP-OES based on the conventional standard addition method (CSAM) and calibration curve method (CCM). Certified standard soils were analyzed by the proposed ISAM method. The values obtained by ISAM method agreed with the certified values. Additionally, the results obtained by ISAM method were compared with those determined by the other two methods (CSAM and CCM). All the values obtained by the ISAM agreed with those from the other two methods. The detection limit, quantification limit, and recovery rate of each method were calculated, and the recovery rates of soil samples and the blank were all within the range of 90%-110%. Finally, the proposed method was applied to determine phosphorous in soil samples from Guangnan County, Yunnan Province, China, and the meadow soil from Qinghai-Tibet Plateau, China. The relative errors between the results from ISAM and CCM were all within 10%, and t-test showed that the results between ISAM and CCM had no significant difference (P > 0.05). Therefore, the proposed method overcame the matrix effect in some extent and was an acceptable method for the rapid and accurate batch analysis of P content in soil sample, especially batch samples with obvious matrix effect.