Band 12, Heft 6 -

Combined osmotic dehydration (sucrose solution: 50–70 % w/w, 30–50 °C for 2 h followed by air drying at 40 and 60 °C) is an appropriate process for preservation of oil retention capacity, lightness and yellowness of lemon peels ( Citrus limon . v. lunari). Incorporation of sugars to lemon cuboids pieces increased drying rate during the first falling rate phase of the air dehydration step and improved their color stability. Osmotic dehydration process allows protective effect against further total phenol loss during air drying: significant loss of total phenol content (70–80 %) was recorded during osmotic dehydration and then it remains constant during air drying at 40 and 60 °C. For the investigated temperature of osmotic pre-treatment (30–50 °C), water retention capacities were reduced by up to 70 % and were maintained constant during air drying.

This article describes the osmotic dehydration of guava dipped in sucrose solutions using two-dimensional numerical solutions of the diffusion equation with boundary condition of the first kind. Two models are used: model 1 disregards the shrinkage of the product and assumes that effective mass diffusivity does not vary during the process; model 2 takes into account shrinkage, considering effective mass diffusivity as variable. Process parameters estimation is obtained by means of an optimizer. Comparative analyzes indicate that the proposed models have similar statistical indicators. However, model 2 is recommended, for it presents much higher physical fitness when describing mass migrations. Comparison between two-dimensional numerical models presented in this research and one-dimensional models found in the literature reveals that one-dimensional models overestimate process parameters. In addition, one-dimensional models present limitations in predicting the distributions of water and sucrose on guava slices.

The phenolic compounds and antioxidant activity of brown rice are well known but the extent to which phenolics and antioxidant activity varies within rice ( Oryza sativa) is not known. This study evaluated the natural variation of phenolic compounds in brown rice of the major cultivars currently grown in China. Free phenolics were extracted with chilled methanol, while bound phenolics were released and extracted by alkaline hydrolysis. There were significant differences in phenolic and flavonoid content between these cultivars and significant differences in bound and total phenolics between japonica and indica samples. Ferulic and p -coumaric acids were the major phenolic acids and existed in both free and bound forms, with the bound form of ferulic acid being a dominant phenolic compound in brown rice. Phenolic compounds were the major contributor to the antioxidant capacity of brown rice and bound phenolics contributed more than free phenolics as estimated using ABTS + radical scavenging method. This study provides additional information on brown rice from japonica and indica subspecies and may assist in retaining or increasing phenolics and antioxidant activity in rice.

In this study, pentacyclic triterpenoids (PTTs) were extracted from loquat leaves by subcritical water extraction (SWE) technique in a dynamic mode. The results revealed that PTTs yield increased up to 5.38±0.12 mg/g with the increasing temperature at 180 °C for corosolic acid (CA) and up to 7.20±0.11 mg/g at 200 °C for ursolic acid (UA) within experimental times. The optimum flow rates to obtain concentrated CA and UA extracts were found to be 33.33 and 41.67 mL/min, respectively. Furthermore, extraction temperatures strongly influenced the extraction rate as demonstrated by the rate constant of each temperature tested. Moreover, the kinetic rate constant decreased as the function of temperature indicating the yield of both CA and UA were significantly influenced by subcritical temperatures and extraction times.

Starches isolated from three different pigmented rice varieties (Chak-hao Amubi, Chak-hao Poireiton, and Chak-hao Angangba) and investigated for their molecular structure and physico-chemical properties including amylose content, morphology, crystallinity, pasting viscosity, color, thermal property, swelling power and solubility. Significant differences were detected in physico-chemical and functional properties ( p ≤0.05 ) of rice starches. The amylose content results revealed that Chak-hao Angangba (1.93 %) and Chak-hao Poireiton (1.98 %) are waxy rice, and Chak-hao Amubi (3.16 %) is a very low-amylose rice. The morphology of rice starch granules shown polyhedral edges with an irregular shape; and the XRD patterns of rice starches exhibited A-type crystalline patterns with peaks at 2θ=15.1°, 17.1°, 18.2° and 23.0°. Waxy rice starches shown higher peak viscosity and enthalpy with lower gelatinization temperatures than very low amylose rice starches. The pasting viscosity, swelling power and solubility crystallinity of rice starches were varied significantly ( p ≤0.05 ). Finally, the present study provides knowledge for the utilization of starches isolated from three pigmented rice varieties grown in North-Eastern part of India that would be relevant for both domestic and industrial applications.

Two ultrasonic systems were compared with different settings for extraction of capsaicinoids (capsaicin, dihydrocapsaicin and nordihydrocapsaicin) from chili peppers. The first system was ultrasonic homogenizer using an ultrasonic probe operating at a working frequency of 20 kHz, with variable setting of power output. The second one was ultrasonic cleaner operating at a working frequency of 35 kHz, with fixed power output of 50 W. Determination of the optimum extraction procedures was performed by comparison of the extraction yields. Content of capsaicinoids was determined by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Optimization studies of extractions by both ultrasonic systems were performed. Ten various real samples of chili underwent optimum extraction conditions in both ultrasonic systems. The results were compared with each other and to a conventional Soxhlet extraction. The ultrasonic methods provide the higher extraction efficiency and simple and straightforward operation. System working at higher power of ultrasound resulted in higher extraction yields. An application of ultrasonic system working at lower frequency of ultrasonic waves is slightly advantageous.

The dynamic flow properties of two important coproducts of virgin coconut oil (VCO) i. e. coconut milk residue flour (MRF) and VCO cake flour (CF) were studied. The basic flowability energy of CF was higher than MRF and increased with moisture content. The change in compressibility and shear stress, with applied normal stress and moisture content, indicated that these powders are highly cohesive. For both flours, the energy required to make the powder flow increased with moisture at all experimental air velocity. Moisture did not significantly influence the cohesion and unconfined yield strength of MRF, whereas for CF there was significant effect due to the presence of moisture. The wall friction angle of both the flours increased significantly with moisture and decreased with applied normal stress. The results from this study indicated that, both CF and MRF at around 4.00 % moisture content had better flow characteristics than at higher moisture levels.

We investigate a flash-assisted extraction of dihydroquercetin (DHQ) from wood sawdust of Larix gmelinii by response surface methodology. Box–Behnken design optimized the extraction conditions, and the highest DHQ yield (6.15 %) was obtained under optimal extraction conditions: FAE time (3 min), extraction time (3 h), solid-to-liquid (g/mL) ratio (1:15), and ethanol concentration (75 %). After purification, the DHQ purity was 96 % as determined by HPLC and was further characterized by FTIR. Purified DHQ’s antioxidant activities were confirmed in vitro by determining DPPH and ABTS radical scavenging activities and reducing Fe 3+ power. In the DPPH and ABTS radical scavenging activity assays, DHQ displayed prominent antioxidant activities with low IC 50 values (11.568 and 12.475 μg/mL, respectively). In reducing Fe 3+ power assay, high DHQ absorbance values showed that DHQ had higher reducing power than butylated hydroxyl toluene and had nearly the same consistent power as ascorbic acid at the same doses.

The study of process kinetics may aid the design and optimization of drying systems. This paper evaluated the influence of drying temperature (40, 60 and 80 °C) on the moisture content, drying rate, density, shrinkage and breakage of maize dried in two different dryers: oven and silo dryer. In both dryers, the temperature increase reduced drying time, final moisture content and shrinkage of the grains, however increased breakage. Drying rate was higher in the oven (6.4×10 −4 ±2.3×10 −4 s −1 versus 5.4×10 −4 ±1.2×10 −4 s −1 ), while shrinkage (15.2±4.7 % versus 24.4±5.6 %) and density increase (16.6±5.9 % versus 33.4±5.8 %) were more intense in the silo. There was a large release of husk in the silo dryer and the moisture content was slightly smaller in the lower layers respective to the upper ones.

An enzymatic-assisted microwave extraction method was developed to extract total flavonoids from bud of Chrysanthemum indicum L. The factors affecting total flavonoid yield were investigated and optimized by response surface design, and this extraction method was compared with water heating extraction. The antioxidant and antimicrobial activities of total flavonoids were preliminarily evaluated. The results showed that the optimized microwave extraction conditions were as follows: water – material ratio, 25:1 (mL:g); extraction time, 19 min; microwave power, 582 W. Under these conditions, the yield of total flavonoids was 11.21 ± 1.12 %, which was 53.21 % higher than water heating extraction method, and had shorter extraction time. The maximum scavenging capacity of total flavonoids (12 mg/mL) on DPPH, hydroxyl and superoxide anion free radical was 76.6 %, 78.8 % and 58.2 %, respectively. The total flavonoids showed inhibitory effect on Bacillus subtilis , Escherichia coli , Staphylococcus aureus and Saccharomyces cerevisiae , with minimum inhibitory concentration of 8 mg/mL, 4 mg/mL, 4 mg/mL and 8 mg/mL, respectively. This study has provided the technical basis for further optimization of extraction of total flavonoids from bud of C. indicum L.