Optimization of bacterial cellulose production by Komagataeibacter sucrofermentans in synthetic media and agrifood side streams supplemented with organic acids and vitamins

The effect of thiamine (TA), ascorbic acid (AA), citric acid, and gallic acid (GA) on bacterial cellulose (BC) production by Komagataeibacter sucrofermentans, in synthetic (Hestrin and Schramm, HS) and natural substrates (industrial raisins finishing side stream extract, FSSE; orange juice, OJ; green tea extract, GTE), was investigated. The Response Surface Methodology was found reliable for BC yield prediction and optimization. Higher yields were achieved in the FSSE substrates, especially those supplemented with AA, TA, and GA (up to 19.4 g BC/L). The yield in the non-fortified substrates was 1.1-5.4 and 11.6-15.7 g/L, in HS and FSSE, respectively. The best yield in the natural non-fortified substrate FSSE-OJ-GTE (50-20-30 %), was 5.9 g/L. The porosity, crystallinity, and antioxidant properties of the produced BC films were affected by both the substrate and the drying method (freeze- or oven-drying). The natural substrates and the process wastewaters can be further exploited towards added value and sustainability. Take Home Message Sentence: Raisin and citrus side-streams can be efficiently combined for bacterial cellulose production, enhanced by other vitamin- and phenolic-rich substrates such as green tea.

Comparison of the effects of three drying methods on lignin properties

In the last few years, a serious effort has been initiated to develop standard methods for lignin characterization at the national and international levels. Thus, several Canadian and ISO standards were recently developed. The current results were generated in an effort to assist the ISO/TC6 Committee come up with a reliable standard method for the measurement of the dry solids content of lignins. In particular, this work investigated the drying of lignin using three different drying methods: conduction oven drying (105 °C), vacuum oven drying at (60 °C), and freeze drying. Ten different lignins were used in this study including wet and air-dried softwood and hardwood kraft lignins in the acid and base forms from the industrial LignoForce™ process and hydrolysis lignin from the TMP-Bio™ process. The results showed that 7 h, 48 h and 24 h were sufficient to reach a constant solids content in the case of all lignins when oven drying, vacuum oven drying under negative pressure (150 mbar), and freeze drying (25 mT) were used, respectively. Kraft lignins in the base form showed higher sensitivity to degradation compared to lignins in the acid form. The total hydroxyl group content of air-dried and wet hardwood lignins in the base form decreased by more than 50 % after vacuum oven-drying for 71.5 h or oven-drying for 16 h compared to freeze-drying for 68 h. The decrease in the total hydroxyl groups was more pronounced (70 %) when the wet softwood lignin in the base form was dried in the oven compared to freeze drying for 68 h.

Effects of different drying methods on Rubus chingii Hu fruit during processing

In this study, the dried fruits of Rubus chingii Hu (Chinese name: Fu-Pen-Zi; FPZ) were processed and dried by three methods-in the shade, the sun, and the oven. The composition regarding the standard ingredient, color, and antioxidant capacities were investigated pro- and post-processing. The technique of headspace-solid-phase-microextraction-gas-chromatography-mass spectrometry (HS-SPME-GC-MS) and flavoromics were used to analyze the flavor-conferring metabolites of FPZ. The results obtained revealed that the highest use value and antioxidant capacities were detected in the FPZ fruits processed and dried in the shade. A total of 358 metabolites were detected from them mainly consisting of terpenoids, heterocyclic compounds, and esters. In differential analysis, the down-regulation of the metabolites was much greater than their up-regulation after all three drying methods. In an evaluation of the characteristic compounds and flavors produced after the three methods, there were variations mainly regarding the green and fruity odors. Therefore, considerable insights may be obtained for the development of novel agricultural methods and applications in the pharmaceutical and cosmetic industries by analyzing and comparing the variations in the chemical composition detected pre- and post-processing of the FPZ fruits. This paper provides a scientific basis for quality control in fruits and their clinical applications.

Effects of different over-fired drying methods on the aroma of Lu'an Guapian tea

Over-fired drying, a crucial process in the production of Lu'an Guapian (LAGP) tea, greatly enriches the tea's aroma. In this study, the aroma compounds of LAGP tea processed through pulley charcoal drying (PCD), roller drying (RD), roller-conveyor drying (RCD), and hot air drying (HD) were analyzed using gas chromatography-mass spectrometry. A subsequent analysis of aroma extraction dilution analysis and odor activity values revealed that (E)-β-ionone, dimethyl sulfide, (E,E)-2,4-heptadienal, geraniol, linalool, benzeneacetaldehyde, coumarin, 2-ethyl-3,5-dimethyl-pyrazine, indole, hexanal, (Z)-jasmone, and (Z)-3-hexen-1-ol were the key contributors to the samples' aroma variation. Moreover, a quantitative descriptive analysis and aroma recombination and omission experiments analysis revealed that (E)-β-ionone is the most critical contributor to the formation of floral aroma in tea processed using PCD, whereas (E,E)-2,4-heptadienal is responsible for the more pronounced fresh aroma in tea processed using HD. In addition, 2-ethyl-3,5-dimethyl-pyrazine contributes to the formation of a roasted aroma in tea processed using RD and RCD. The study results provide a theoretical basis for choosing the processing method, especially for drying, to obtain high-quality LAGP tea.

Thermal treatment enhances the resisting exercise fatigue effect of Phyllanthus emblica L.: novel evidence from tannin conversion in vitro, metabolomics, and gut microbiota community analysis

Polyphenols are the main component of Phyllanthus emblica (PE). However, polyphenols are so easy to transform that it is unknown that how drying methods driven by heating affect the anti-fatigue effect of PE. This manuscript investigated the effects of five drying methods on the chemical composition transformation and anti-fatigue of PE, and discussed the action mechanism. The results suggested that the anti-fatigue effect of PE with hot-air-dried at 100 °C was the best, which was as 1.63 times as that with freeze-drying. Ellagic acid (EA) may be a key component of PE in anti-fatigue, and its mechanism of action may be related to regulating intestinal microbiota, protecting mitochondria, and regulating energy metabolism. This study first revealed the thermal transformation of polyphenols in PE, found the most effective strategy for enhancing the anti-fatigue function, and explores its action mechanism.

Effects of spray drying and freeze drying on the structure and emulsifying properties of yam soluble protein: A study by experiment and molecular dynamics simulation

This study focused on the effects of freeze drying (FD) and sprays drying (SD) on the structure and emulsifying properties of yam soluble protein (YSP). The results showed that the surface hydrophobicity (Ho) value, free sulfhydryl group (SH) content, turns content, denaturation temperature and enthalpy value of spray-dried YSP (SD-YSP) were higher than freeze-dried YSP (FD-YSP), but the apparent hydrodynamic diameter (Dh) value of SD-YSP was smaller. The smaller Dh, higher Ho and free SH led to higher percentage of adsorbed proteins and stronger binding between protein and oil droplet in emulsions. Thus, the emulsifying properties of SD-YSP were better, and the SD-YSP-stabilized emulsion had better dynamical rheological properties. Molecular dynamics (MD) simulations suggested that some intramolecular disulfide bonds and hydrogen bonds of dioscorin were broken, and some helices transformed into turns during the SD process. These structural changes resulted in better thermal stability and emulsification properties of SD-YSP.

Assessment of fresh Alpinia galanga (A. galanga) drying techniques for the chemical composition of essential oil and its antioxidant and biological activity

This study evaluated drying characteristics, structure and essential oil chemical composition, and biological activity of A. galanga by hot air drying (HAD), vacuum drying (VD), freeze drying (FD). The results showed that HAD had the shortest drying time while FD could better maintain the microstructure and showed a higher essential oil yield than HAD and VD. In addition, E-nose, HS-GC-IMS and HS-SPME-GC-MS could effectively distinguish the essential oil chemical composition of the four samples because different drying methods induced the changes in the profile and content of the compounds. HS-SPME-GC-MS detected 43 compounds, of which alcohols, alkenes, and esters were the main substances in fresh and dry samples. In comparison, HS-SPME-GC-IMS detected 80 compounds, including alcohols, aldehydes, ketones, esters, alkenes. Overall, the FD samples showed more outstanding advantages by evaluating antioxidant properties and antibacterial activities. FD was more suitable for A. galanga drying as it maintains appearance and biological activity.

Effect of different drying methods on free amino acid and flavor nucleotides of scallop (patinopecten yessoensis) adductor muscle

The effects of hot air drying (HAD), vacuum hot air drying (VHAD), microwave drying (MWD), and vacuum freeze drying (VFD) on free amino acids (FAAs) and flavor nucleotides in scallop adductor muscle (SAM) were studied. The liquid chromatography and multidimensional infrared spectroscopy (MM-IR) were used. Compared with fresh SAM, the main FAAs were glycine, alanine, arginine, and glutamic acid in dried SAM. The total FAAs content in VFD group was 1.40-1.90 times of the other group. The umami taste nucleotides (IMP and AMP) content in the VFD and MWD groups was significantly higher than that in HAD and VHAD groups. Equivalent umami concentrations were found: VFD > MWD > VHAD > HAD. MM-IR analysis was an efficient method for identifying taste components. The results revealed FAAs and flavor nucleotides and the mutual adjustment of compounds were related to drying method, and VFD was preferred for taste substance retention in scallops.

Comparative elucidation of bioactive and volatile components in dry mature jujube fruit (Ziziphus jujuba Mill.) subjected to different drying methods

•

Convective drying(CD) increased the concentrations of rutin, epicatechin and quercetin in jujube, and the total phenolic content was not significantly different with freeze-drying(FD).

•

Six volatile components with OVA >1 were identified in dried jujube, and their concentration changes were related to precursor substances.

•

The volatile components expressing “Fruity” aromas increased after CD, and the expression of fruity aromas at CD60 even exceeded that of FD samples.

•

CD60 is an efficient drying method with potential to replace FD in terms of bioactivity and aroma.

This study investigated the effects of convective drying(CD) and freeze drying(FD) on bioactive and volatile components in jujube. No significant difference in total phenolic, total flavonoids and antioxidant capacity among CD60, CD70, CD80 and FD samples (P > 0.05). LC-MS/MS analysis showed that this trend mainly originated from the dynamic equilibrium relationships between caffeic acid, chlorogenic acid, p-hydroxybenzoic acid, rutin, epicatechin, and quercetin. HS-SPME-GC–MS identified 31 volatile organic compounds (VOCs) comprising more than 80% aldehydes and acids. Principal component analysis distinguished the VOC characteristics of samples subjected to different drying methods. Six VOCs had an odor activity value (OAV) >1, most of which were fatty acid oxidation or Maillard reaction products. Combined with the precursor components, these reactions were speculated to be the major VOC-producing pathways in dried jujube. Considering the bioactive components and flavor retention, CD at 60 °C was an effective drying method with potential to replace FD.

Discovery of an effective processing method for edible rhizome to enhance the gamma-aminobutyric acid content

This study aimed to discover a simple, rapid, effective, inexpensive, and natural method to enhance the GABA content in edible rhizomes. To achieve this aim, edible rhizome samples were treated with different processing methods. Drying with hot air increased the GABA content in Chinese yam (CY) eight-fold compared with untreated CY. Drying with sunshine or hot air increased it 13- and 28-fold in taro root, respectively. These processing methods also produced an apparent increase in the GABA contents in other edible rhizome, such as lotus rhizomes, potatoes, and sweet potatoes. However, lyophilization did not affect the GABA content. Further, HPLC data showed that while GABA levels increased, glutamate levels decreased, indicating that GABA is produced by the catalytic action of glutamate decarboxylase on glutamate under drought conditions. Drying with hot air or sunshine to enhance the GABA content was not indicated in the literature.

Microwave technology: a novel approach to the transformation of natural metabolites

Microwave technology is used throughout the world to generate heat using energy from the microwave range of the electromagnetic spectrum. It is characterized by uniform energy transfer, low energy consumption, and rapid heating which preserves much of the nutritional value in food products. Microwave technology is widely used to process food such as drying, because food and medicinal plants are the same organisms. Microwave technology is also used to process and extract parts of plants for medicinal purposes; however, the special principle of microwave radiation provide energy to reaction for transforming chemical components, creating a variety of compounds through oxidation, hydrolysis, rearrangement, esterification, condensation and other reactions that transform original components into new ones. In this paper, the principles, influencing factors of microwave technology, and the transformation of natural metabolites using microwave technology are reviewed, with an aim to provide a theoretical basis for the further study of microwave technology in the processing of medicinal materials.

Effects of drying methods on oxidative stability of roselle seed oil (Hibiscus Sabdariffa): an optimization approach

The objective of this study was to optimize the extraction of oil from pre-dried roselle seeds using response surface methodology (RSM). We also determined the oxidative stability of oil extracted from oven and freeze-dried roselle seed in terms of iodine value (IV), free fatty acid (FFA) value, peroxide value (PV), P-anisidine and total oxidation values (TOTOX value). The RSM was designated based on the central composite design with the usage of three optimum parameters ranged from 8 to 16 g of sample weight, 250-350 mL of solvent volume, and 6-8 h of extraction time. The highest oil yielded from roselle seed using the optimization process was 22.11% with the parameters at sample weight of 14.4 g, solvent volume of 329.70 mL, and extraction time of 7.6 h. Besides, the oil extracted from the oven dried roselle seed had the values of 89.04, 2.11, 4.13, 3.76 and 12.03 for IV, FFA, PV, P-anisidine, and TOTOX values, respectively. While for the oil extracted from freeze-dried roselle seed showed IV of 90.31, FFA of 1.64, PV of 2.47, P-anisidine value of 3.48, and TOTOX value of 8.42. PV and TOTOX values showed significant differences whereas; IV, FFA, and P-anisidine values showed no significant differences between the oven and freeze-dried roselle seed oils.

Nanocellulose-based lightweight porous materials: A review

Nanocellulose has been widely concerned and applied in recent years. Because of its high aspect ratio, large specific surface area, good modifiability, high mechanical strength, renewability and biodegradability, nanocellulose is particularly suitable as a base for constructing lightweight porous materials. This review summarizes the preparation methods and applications of nanocellulose-based lightweight porous materials including aerogels, cryogels, xerogels, foams and sponges. The preparation of nanocellulose-based lightweight porous materials usually involves gelation and drying processes. The characteristics and influencing factors of three main drying methods including freeze, supercritical and evaporation drying are reviewed. In addition, the mechanism of physical and chemical crosslinking during gelation and the effect on the structure and properties of the porous materials in different drying methods are especially focused on. This contribution also introduces the application of nanocellulose-based lightweight porous materials in the fields of adsorption, biomedicine, energy storage, thermal insulation and sound absorption, flame retardancy and catalysis.

Assessment of fresh star anise (Illicium verum Hook.f.) drying methods for influencing drying characteristics, color, flavor, volatile oil and shikimic acid

In order to evaluate the effects of drying methods on the drying characteristics, quality (color, volatile oil (VO) content, shikimic acid (SA) content, trans-anethole content in the star anise volatile oil (TA-O)) and flavor components of star anise (Illicium verum Hook.f.), we tested five different methods (hot air drying (HAD), heat pump drying (HPD), far infrared radiation drying (FIRD), microwave drying (MD), and sun drying (SD)) with or without blanching to dry fresh star anise. Results showed MD had a shorter drying time than others, as well as the highest SA content (125.56 mg/g d.b.). HPD sample exhibited higher VO content (12.27% d.b.) and TA-O (113.30 mg/g d.b.) than those dried with other methods. HPD can improved the dominant flavor compounds of star anise, including trans-anethole (4165.46 mg/100 g d.b.), estragole (176.50 mg/100 g d.b.), linalool (280.69 mg/100 g d.b.), and (+)-limonene (471.18 mg/100 g d.b.). Samples treated with HPD-B had the highest comprehensive score (4.59) in the flavor principal component analysis. Therefore, HPD was more suitable for star anise drying as it maintaining quality. The better quality (higher flavor quality and better appearance) was found in HPD-B.

Comparison of structural characteristics and bioactivities of polysaccharides from loquat leaves prepared by different drying techniques

In the present study, freeze drying, hot-air drying, vacuum drying, and microwave drying at the microwave powers of 400, 600, and 800 W, respectively, were utilized to dry loquat leaves for evaluating the effects of different drying techniques on the physicochemical structures and bioactivities of polysaccharides extracted from loquat leaves (LLPs). Results demonstrated that the physicochemical structures and bioactivities of LLPs significantly affected by different drying techniques. The degrees of esterification, molar ratios of constituent monosaccharides, contents of uronic acids, apparent viscosities, and molecular weights of LLPs were varied by different drying techniques. Additionally, LLPs, particularly LLP-M4 which extracted from loquat leaves prepared by microwave drying at the power of 400 W, exerted remarkable in vitro binding capacities, strong inhibitory effects on α-amylase and α-glucosidase, and obvious antioxidant activities. Results indicated that the microwave drying could be an efficient drying technique before extraction of bioactive LLPs, and LLPs had great potential applications in the functional food and pharmaceutical industries.

Influences of different drying methods on the structural characteristics and multiple bioactivities of polysaccharides from okra (Abelmoschus esculentus)

In this study, in order to evaluate the influences of drying methods on the chemical structures and bioactivities of polysaccharides from okra (OPPs), four drying methods, including microwave drying at 400 W, 600 W, and 800 W, freezing drying, hot air drying, and vacuum drying, were applied to dry okra fruits. Six different OPPs were extracted from okra dried by different drying methods. Results showed that physicochemical characteristics and bioactivities of OPPs varied by different drying methods. Noticeable variations in extraction yields, molecular weights, rheological properties, molar ratios of constituent monosaccharides, contents of uronic acids, degrees of esterification, and contents of total phenolics were observed in OPPs obtained by different drying methods. In addition, results showed that OPPs, especially OPP-H and OPP-V obtained by hot air drying and vacuum drying, respectively, exhibited remarkable antioxidant activities (ABTS, DPPH, and nitric oxide radical scavenging activities, and ferric reducing antioxidant powers), strong in vitro binding capacities (fat, cholesterol, and bile acids binding capacities), and obvious inhibitory activities on α-amylase and α-glucosidase. Results suggested that the hot air and vacuum drying techniques could be appropriate drying methods before extraction of OPPs with high bioactivities for applications in the functional food and medicine industries.

Comparison of quality and microstructure of chokeberry powders prepared by different drying methods, including innovative fluidised bed jet milling and drying

The study assessed the functional properties, microstructural features and sensory characteristics of chokeberry powders obtained by the new fluidised bed jet milling and drying method as compared to other drying methods such as freeze-drying, vacuum drying and convection drying. The new method was based on simultaneously drying and milling plant material which had been subjected to partial air drying at 70 °C prior to this treatment. The technique resulted in the production of good quality fruit powders with high vitamin C and polyphenolic content, as well as high antioxidant activity. Favourable physiochemical characteristics and sensory qualities were also observed together with low water activity. The new fluidized bed jet milling and drying therefore compared very favourably with freeze-drying, vacuum drying and convection drying when considering the content of bioactive substances, physiochemical features and the sensory quality of the prepared powders.

Preparation and characterization of porous starch reinforced with halloysite nanotube by solvent exchange method

The aim of this study was to improvement of adsorption capacity of porous starch (PS) by incorporation of halloysite nanotube (HNT). PS/HNT carrier was synthesized through the solvent exchange method. Various fabrication approaches for PS were introduced and different ethanol ratio (40, 60, 80, 100%), HNT concentration (0, 0.1, 0.2, 0.3, 0.4 and 0.5 mg/mL) and drying method (oven, freeze dryer and microwave) were applied. The results indicated that high ratio of ethanol created larger pores and also the best results were obtained from freeze-dried samples (p < 0.05). Incorporation of HNT could further improve the adsorption capacity. However, the best oil and water adsorption capacity were related to PS alone. The nitrogen adsorption-desorption measurement and scanning electron microscopy elucidated the porous structure of samples. The experimental data were fitted successfully by the Langmuir model rather than Freundlich isotherm. Also PS/HNT had higher apparent density and more negative zeta potential rather than PS. However, the DSC results showed the similar thermal patterns for PS and PS/HNT.

Effect of different drying methods on the product quality and bioactive polysaccharides of bitter gourd (Momordica charantia L.) slices

In this study, three drying methods, namely, hot-air drying, freeze drying (FD), and infrared radiation drying (ID), were applied to dry bitter gourd (Momordica charantia L.) slices. Results showed that the drying methods had significant influences on appearance, color, rehydration ratio, and microstructure of dried bitter gourd. FD provided high-quality dried bitter gourd products due to the uniform honeycomb network and less collapsed structure. Three water-soluble bitter gourd polysaccharides (BPS-H, BPS-F, and BPS-I) were obtained from the bitter gourd dried using the three drying methods. The three polysaccharides exhibited similar preliminary structural characteristics with different monosaccharide compositions and molecular weights. BPS-I obtained from ID-dried bitter gourd had higher sugar and uronic acid contents than BPS-H and BPS-F. BPS-I exhibited stronger antioxidant activities and bile acid-binding capacity in vitro than BPS-H and BPS-F. Moreover, BPS-F and BPS-I showed significant α-amylase inhibitory activities in vitro.

Effects of drying methods on contents of bioactive compounds and antioxidant activities of Angelica dahurica

Baizhi (Angelica dahurica) has been widely used as a traditional Chinese herbal medicine, functional food and cosmetic product ingredient, mostly because of the high furanocoumarin compounds in roots. Because the fresh root is perishable, drying techniques are needed to maintain a higher-quality product. Freeze-drying is the best method but energy-consuming and costly. The aim of this study was to analyze the quality (antioxidant and furanocoumarin content) of Baizhi roots after freeze-drying (the control) and in-the-shade, 40 and 70 °C drying. Antioxidant activity was revealed by 2,2-diphenyl-1-picrylhydrazyl and Fe2+ chelating assay, and the content of six furanocoumarin compounds, including xanthotoxin, bergapten, oxypeucedanin, imperatorin, phellopterin and isoimperatorin, was analyzed by liquid chromatography. Antioxidant activity was greater in roots with in-the-shade, 40 and 70 °C drying than freeze-drying. The furanocoumarin content pattern was similar with 70 °C drying and freeze-drying. A. dahurica roots dried at 70 °C may be an alternative method for maintaining high quality.

Effect of boiling and drying process on chemical composition and antioxidant activity of Chaenomeles speciosa

Chemical composition and antioxidant activity of fresh and boiled Chaenomeles speciosa (CS) slices dried by different drying methods were determined. Data were analyzed by principle component analysis and cluster analysis. All dried boiled CS from dried fresh CS slices form main cluster. The results also demonstrated that both drying methods, freeze drying and hot air drying at 60 °C had good potential in the industrial drying of fresh and boiled CS. Fresh CS dried by hot air drying at 60 °C was more suitable for the industrial production.

Thermal drying of the solid fraction from biogas digestate: Effects of acidification, temperature and ventilation on nitrogen content

Drying of solids produced from digestate is prone to N losses through NH3 volatilisation. The applicability of acidification as an NH3 emission mitigation technique during the drying of solids from digestate was assessed in a drying experiment. Operating conditions comprised four drying temperatures (70-160°C), two air ventilation rates (natural, 420ml/min) and three pH levels (9.2, 6.5 and 5.5) of the solids, modified by the addition of concentrated sulphuric acid. Acidification of the solids from digestate significantly decreased the NH3 emission during drying, irrespective of the drying conditions. A parallel decrease in the organic nitrogen content and an increase in the ammonium content of the solids was observed after acidification of the solids. It was confirmed that acidification before thermal concentration of solids from digestate, minimised NH3 losses under a wide range of drying conditions.

Physicochemical characterization of the polysaccharide from Bletilla striata: effect of drying method

The polysaccharide from Bletilla striata, a traditional Chinese herbal medicine, was obtained by different drying techniques: vacuum-drying (BVPS) or vacuum freeze-drying (BFPS). The effect of drying method on the physicochemical properties of the B striata polysaccharide was evaluated using high size exclusion chromatography coupled to multiangle laser light scattering (HPSEC-MALLS), FT-IR and UV spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The monosaccharide analysis and pH test revealed that the polysaccharide derived from B. striata was a neutral polysaccharide that is composed of glucose and mannose. The solubility and moisture content test's results demonstrated that BFPS was greater than BVPS. The number average molecular weight (Mn) and the computed average molecular weight (Mw) of 99.3% BFPS were 7.297×10(4)g/mol and 9.545×10(4)g/mol, respectively, whereas the Mn and Mw of 97.6% BVPS were 1.218×10(5)g/mol and 1.472×10(5)g/mol, respectively. The FT-IR and UV results indicated that drying technique has little effect on the structure of the polysaccharide. The thermal analysis showed that weight loss event was at 307.85°C and 305.50°C to BVPS and BFPS, respectively. Furthermore, the XRD confirmed that the polysaccharide was the amorphous nature. However, both SEM and AFM images exhibited that the drying technique had a significant impact on the morphology and conformation of the polysaccharide.

Physicochemical and thermal properties of taro (Colocasia esculenta sp) powders as affected by state of maturity and drying method

The study was aimed at determining the effect of harvesting time and drying method on the thermal and physicochemical properties of taro powder, Sosso ecotype. A 5 × 2 factorial experiment with 5 harvesting times (6, 7, 8, 9 and 10 months after planting) and 2 drying methods (sun and electric oven drying) was used for this purpose. The variance component analysis revealed harvesting time as the most important factor affecting all the variables measured. In particular the proteins and available sugar contents of the powders increased significantly with increase in harvesting time. The same was true of the gelling property and water absorption capacity of the powders. It was equally observed that the temperatures (start, peak and end) and enthalpy of gelatinization of the powders increased with harvesting time. It is concluded that harvesting sosso-taro at full maturity (10 months after planting) and sun-drying produces food powders with excellent gelling properties among others.