Artificial Neural Network-Based Microwave Satellite Soil Moisture Reconstruction over the Qinghai–Tibet Plateau, China

Soil moisture is a key parameter for land-atmosphere interaction system; however, fewer existing spatial-temporally continuous and high-quality observation records impose great limitations on the application of soil moisture on long term climate change monitoring and predicting. Therefore, this study selected the Qinghai–Tibet Plateau (QTP) of China as research region, and explored the feasibility of using Artificial Neural Network (ANN) to reconstruct soil moisture product based on AMSR-2/AMSR-E brightness temperature and SMAP satellite data by introducing auxiliary variables, specifically considering the sensitivity of different combination of input variables, number of neurons in hidden layer, sample ratio, and precipitation threshold in model building. The results showed that the ANN model had the highest accuracy when all variables were used as inputs, it had a network containing 12 neurons in a hidden layer, it had a sample ratio 80%-10%-10% (training-validation-testing), and had a precipitation threshold of 8.75 mm, respectively. Furthermore, validation of the reconstructed soil moisture product (named ANN-SM) in other period were conducted by comparing with SMAP (April 2019 to July 2021) for all grid cells and in situ soil moisture sites (August 2010 to March 2015) of QTP, which achieved an ideal accuracy. In general, the proposed method is capable of rebuilding soil moisture products by adopting different satellite data and our soil moisture product is promising for serving the studies of long-term global and regional dynamics in water cycle and climate.

Phenolic Content, Main Flavonoids, and Antioxidant Capacity of Instant Sweet Tea (Lithocarpus litseifolius [Hance] Chun) Prepared with Different Raw Materials and Drying Methods

This study aims to investigate the effects of raw materials and drying methods on the phytochemical and antioxidant capacities of instant sweet tea powder. Four raw materials of sweet tea leave powders (STUT) were extracted and dried with two methods (freeze-drying and spray-drying). The antioxidant capacity, total phenolic content (TPC), total flavonoid content (TFC), and phlorizin and trilobatin contents of obtained instant sweet tea powders were compared. In addition, the single-factor experiments coupled with response surface methodology were used to study the influences of solvent-to-sample ratio, extraction temperature, extraction time, and their interactions on instant sweet tea yield. Results showed that the optimal conditions for extraction were the solvent-to-sample ratio of 19:1 mL/g, extraction temperature of 88 °C, and extraction time of 30 min. The TPC, TFC, antioxidant capacities, and phloridzin and trilobatin contents of instant sweet teas were higher than those of STUT, and the TPC and TFC of freeze-dried instant sweet teas were higher than those of spray-dried instant sweet teas. Significant correlations were found among TPC, TFC, and antioxidant capacities (p < 0.01). The freeze-dried instant sweet tea produced by young leaves (prepared by oven-drying) showed the highest TPC, TFC, and antioxidant capacities, compared with other raw materials and drying methods.

Optimization and assessment of a sequential extraction procedure for calcium carbonate rocks

Sequential extraction analyses are widely used for the determination of element speciation in sediments and soils. Typical sequential extraction protocols were developed to extract from low-carbonate samples and therefore are not necessarily suitable for high-carbonate samples. In this study, we tested increased reagent to sample ratios to adjust an existing sequential extraction procedure to analyze high-CaCO3 samples with concentrations ranging from 70 to above 90 %. Complete dissolution of the CaCO3 phase, and a higher extraction efficiency of manganese associated with the carbonate phase, was achieved when using four times the original reagent to sample ratio in the 2nd extraction step. This increase of reagent did not compromise the extraction of subsequent phases as shown by unaffected Fe concentrations in a low-carbonate sample. Hence, an essential outcome was that increasing the solution to sample ratio did not lead to the dissolution of other sedimentary phases, such as hydrous and crystalline iron oxides or sulfides. Thus, compared to other extraction protocols that use a lower reagent to sample ratio in the carbonate dissolution step, the new protocol allowed the complete extraction of oxide and sulfide phases in the following extraction steps. Furthermore, the study demonstrated the benefit of replacing Na-acetate with NH4-acetate to extract exchangeable ions and carbonates. We observed increased intensities for several analytes, i.e., trace metals such as Mo and As, due to less suppression of the analyte signal by NH4-acetate than by Na-acetate during analysis by inductively coupled plasma optical emission spectrometry (ICP-OES).

Isolation of Prebiotics from Artocarpus integer’s Seed

There has been a high amount of attention given to prebiotics due to their significant physiological function and health benefits. Prebiotics contain nondigestible compounds that allow specific changes, both in the growth and in the activity of bacteria in the host gastrointestinal tract, that provide benefits upon the host by promoting a healthy digestive system and preventing disease. This study aims at investigating the potential prebiotic activity of bioactive compounds extracted from the seeds of an underutilized indigenous plant Artocarpus integer (A. integer). The optimum microwave-assisted extraction conditions were a microwave power of 1500 W, extraction time of 180 s, and solvent-to-sample ratio of 1000 : 1. The maximum amount of the total carbohydrate content extracted from A. integer was 787 mg/L. The percentage hydrolysis levels of A. integer extract in gastric juice at pH 1, 2, 3, and 4 were 6.14%, 7.12%, 8.98%, and 10.23%, respectively. For enzymatic digestion, the percentage of hydrolysis was 0.16% at pH 7. A. integer extract was found to support the growth of probiotics such as L. acidophilus and L. casei. After 72 hours of incubation, L. acidophilus achieved 6.96 log 10 CFU, whereas L. casei reached 8.33 log 10 CFU. The study makes an important contribution to the development of the use of Sarawakian underutilized plants and to the identification of new sources of prebiotic materials to be used in food.

Statistical Optimization of Flavonoid and Antioxidant Recovery from Macerated Chinese and Malaysian Lotus Root (Nelumbo nucifera) Using Response Surface Methodology

In this study, the combination of parameters required for optimal extraction of anti-oxidative components from the Chinese lotus (CLR) and Malaysian lotus (MLR) roots were carefully investigated. Box–Behnken design was employed to optimize the pH (X1: 2–3), extraction time (X2: 0.5–1.5 h) and solvent-to-sample ratio (X3: 20–40 mL/g) to obtain a high flavonoid yield with high % DPPHsc free radical scavenging and Ferric-reducing power assay (FRAP). The analysis of variance clearly showed the significant contribution of quadratic model for all responses. The optimal conditions for both Chinese lotus (CLR) and Malaysian lotus (MLR) roots were obtained as: CLR: X1 = 2.5; X2 = 0.5 h; X3 = 40 mL/g; MLR: X1 = 2.4; X2 = 0.5 h; X3 = 40 mL/g. These optimum conditions gave (a) Total flavonoid content (TFC) of 0.599 mg PCE/g sample and 0.549 mg PCE/g sample, respectively; (b) % DPPHsc of 48.36% and 29.11%, respectively; (c) FRAP value of 2.07 mM FeSO4 and 1.89 mM FeSO4, respectively. A close agreement between predicted and experimental values was found. The result obtained succinctly revealed that the Chinese lotus exhibited higher antioxidant and total flavonoid content when compared with the Malaysia lotus root at optimum extraction condition.

Process Optimization for Ultrasound-Assisted Starch Production from Cassava (Manihot esculenta Crantz) Using Response Surface Methodology

Ultrasound-assisted extraction (UAE) has been optimized to improve the current cassava starch production by conventional maceration for the extraction method. Evaluation of several extraction parameters disclosed significant effects (p < 0.05) by three studied factors (ultrasound power, x1; pulse duty-cycle, x2; and solvent to sample ratio, x3). Subsequently, a Box-Behnken design (BBD) in conjunction with response surface methodology (RSM) was employed to optimise the three factors at three levels: x1 (30, 60, 90%), x2 (0.3, 0.6, 0.9 s−1), and x3 (10:1, 20:1, 30:1). The model built for the RSM was validated through the coefficient of determination (R2 > 0.95), prediction error (2.12%), and lack-of-fit (0.71) values. The model validation suggested that the RSM was adequate for the observed data at the 95.0% confidence level. The optimum yield of cassava starch extraction was achieved by applying 90% for ultrasound power, pulse duty-cycle of 1.0 s−1, and solvent to sample ratio of 30:1 with 10 min extraction time. Finally, the UAE produced starch with a purity of 88.36% and a lower viscosity than the commercial sample due to the granules’ size alteration. Hence, apart from speeding up the extraction process, UAE was worthwhile for the starch modification that could maintain the viscosity at a lower value (1920 cP) than the commercial starch (1996 cP) at the highest studied temperature treatment of 70 °C.

Optimization and Comparison of Ultrasound and Microwave-Assisted Extraction of Phenolic Compounds from Cotton-Lavender (Santolina chamaecyparissus L.)

The interest in natural phenolic compounds has increased because of their attractive use especially as antioxidant and antimicrobial agents in foods. The large content in phenolic compounds of interest in Santolina chamaecyparissus L. (S. chamaecyparissus) makes this plant a target source that is worthy of note. In this work, new extraction technologies comprising ultrasound (UAE) and microwave (MAE) assisted extraction of the phenolic compounds in S. chamaecyparissus have been developed, optimized, and compared. Several extraction factors have been optimized based on a Box-Behnken design. Such optimized factors include the percentage of methanol in water (25–75%), the temperature (10–70 °C), the ultrasound amplitude (20–80%), the ultrasound cycle (0.2–1 s), the solvent pH (2–7) and the solvent-sample ratio (5/0.2–15/0.2 mL/g) with regard to UAE, while the percentage of methanol in water (50–100%), the temperature (50–100 °C), the pH (2–7) and the solvent-sample ratio (5/0.2–15/0.2 mL/g) were optimized for MAE. The solvent composition was the most influential parameter both on MAEs (64%) and UAEs (74%). The extraction optimum time was established as 15 min for MAE and 25 min for UAE. Five major phenolic compounds were detected and identified by Ultra-High-Performance Liquid Chromatography—Quadrupole Time of Flight—Mass Spectrometry (UHPLC-QToF-MS) in the extracts: chlorogenic acid, quercetin 3-O-galactoside, quercetin 3-O-glucoside, isoorientin, and cynarin. With the exception of chlorogenic acid, the other four compounds have been identified for the first time in S. chamaecyparissus. The findings have confirmed that MAE is a significantly more efficient extraction method than UAE to extract phenolic compounds from S. chamaecyparissus.

Optimization of the extraction of phenolic compounds and antioxidant activity from the roots of Waltheria ovata using the response surface methodology

Waltheria ovata is a medicinal plant belonging to the Sterculiaceae genus. Natural products of Waltheria ovata could be used in the food industry as natural antioxidants due to its high content of polyphenols according to the literature. The main objective in this research was to optimize the extraction of phenolic compounds and the antioxidant activity from Waltheria ovata roots using response surface methodology (RSM). The total phenolic content in different extracts was determined by spectrophotometric method (Folin-Ciocalteu reagent) and the antioxidant activity by using DPPH assay. To optimize the conditions for total phenolic content and antioxidant activity were used three independent variables: solvent/sample ratio (1:10, 1:20 and 1:30 g/mL), temperature (40, 50, and 60°C) and time (40, 50 and 60 mins). The results showed that total phenolic content and antioxidant activity in the experiments ranged from 8.7 to 12.1 mg GAE/g and 76.1% to 96.7%, respectively. The coefficients of determination (R2 values) for phenolic content and antioxidant activity were 0.86 and 0.91, respectively. Under the optimum conditions of 1:20 g/mL, 60°C and 55 mins of extraction, the values for total phenolic content and antioxidant activity were 0.448±0.02 mg GAE/g and 87.00±2.0%, respectively. These data showed that the experimental responses were reasonably close to the predicted responses (0.444 mg GAE/g and 84.67%). Therefore, the results showed that Waltheria ovata can be used as antioxidant in foods.