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Industrially, the use of far-infrared (FIR) as a heat source for drying daylily presents some issues, such as high energy consumption and large loss of nutrients. The use of mid-infrared (MIR) was performed to study the drying of daylily to explore its advantages, with the FIR drying as a comparison. Drying models were established by the drying kinetics, and the changes of nutrition, rehydration ratio (RR) and water migration pattern were researched. The results showed the best-fitting drying model was the Modified Henderson and Pabis model. Under the same temperature, compared with FIR drying, the drying time of MIR drying was shortened by 50%, the effective moisture diffusivity (D eff) was increased by 103%, the drying activation energy (E a) was reduced by 10%, the reducing sugar and ascorbic acid retention rate was increased by 13.9% and 9.7%, respectively. The MIR drying had better RR and water migration characteristics.

A cold plasma (CP) assisted Maillard reaction (MR) is innovatively proposed to improve the hydration property and antioxidant activity of high-denatured peanut protein isolate (HPPI) which is limited in the food industry due to poor solubility. The physicochemical properties (hydration, rheological, thermal and antioxidant properties) and the structure of CP-induced glycosylation products were investigated. The results showed that the CP treatment facilitated the degree of grafting and browning. With CP treatment, the solubility (from 610.0 g/L to 1580.0 g/L), the bound water content and the hydrophilic -OH content increased. The HPPI exposed more active amino groups and interacted with sesbania gum molecules with covalent bonding. Those changes were conducive to the formation of the hydrophilic surface of glycosylation products and gel network structure. The antioxidant activity of glycosylation product was significantly increased. The CP-assisted MR may be an efficient and energy-saving approach to improve the functional properties of HPPI in the food industry.

The kinetics of the K2S2O8-initiated inverse emulsion polymerization of aqueous sodium acrylate solutions in kerosene with Span 80 as the emulsifier has been studied. The conversion-time curves are S-shaped. The following expressions have been obtained for the maximum rate of polymerization and the molecular weight of the polymers under the experimental conditions investigated: Rmax ∞ [K2S2O8]0.78[sodium acrylate]1.5[Span 80]0.1, (OVERLINE)M(/OVERLINE)u ∞ [K2S2O8]−0.37[sodium acrylate]2.9[Span 80]−0.2. The activation energy for the maximum rate of polymerization is 94.8 kJ mol−1. The results suggest a monomer–droplet–nucleation mechanism for the system studied. © 1996 John Wiley & Sons, Inc.

Pulse and γ-radiolysis of concentrated perchloric acid solutions has been investigated. Since perchlorate ion is unreactive to the water decomposition products such as eeq–, H and OH, solute decomposition occurs only through the direct effect of radiation. From pulse radiolysis experiments using scavengers, G(ClO4˙)= 0.083 ± 0.01 and G(ClO3˙)= 0.052 ± 0.01 µmol J–1 have been determined. In highly concentrated solutions, two components with transient absorption at 350 and 440 nm are observed. The shorter-wavelength component is attributed to ClO3˙. G(ClO3˙) calculated using Iµ= 470 m2 mol–1 at the peak is 0.052 µmol J–1, which is consistent with the value determined from scavenger experiments. The longer-wavelength component is detected in perchloric acid solutions with concentration > 10 mol dm–3. This species is tentatively assigned to HClO4+, formed in the direct decomposition of HClO4 molecule. From γ-radiolysis G(ClO3–)= 0.10 ± 0.01 µmol J–1 was determined, and O(3P) is formed together with ClO3–. With G(ClO4˙)= 0.083, G(ClO3˙)= 0.052 and G(ClO3–)= 0.10 µmol J–1 and the reaction scheme proposed in this work, the yields of the final products reported previously can be explained.

The kinetics of the 60 Co γ ray-initiated inverse emulsion polymerization of aqueous sodium acrylate solutions in kerosene with Span 80 as the emulsifier was investigated. The conversion-time curves were analyzed using the equation [ex/(1 - e) - In(1 - x)] = B (constant) + [nk p /(V p ∞N A )]t, derived on the basis of a monomer droplet nucleation mechanism. The following expressions were obtained for K = [nk p /(V p ∞N A )] under the experimental conditions investigated : K ∞ [dose rate] 0.9 [sodium acrylate] 0.5 [Span 80] 0.4 , which was simplified to n ∞ [dose rate] 0.9 , nk p ∞ [sodium acrylate] 0.5 , and n/V p ∞ ∞ [Span 80] 0.4 . The polymerization rate during the steady state (approximate conversion range 20-80%) could be expressed by R p = KxC 0 ∞ [dose rate] 0.9 [sodium acrylate] 1.5 [Span 80] 0.4 . The kinetic analysis suggests a dose rate independent polymerization process for the system studied such that, at any time, there was only one active passage of radiation through a droplet, viz., all polymer radicals resulting from a radiation passage were terminated before another passage.

A pulse radiolysis study of aqueous nitric acid and nitrate solutions has been carried out. The formation kinetics of NO{sub 3} radical was followed with nanosecond time resolution. Two formation processes of NO{sub 3} in nitric acid solutions were directly demonstrated: a fast one completed during the electron pulse and a slow one occurring in a microsecond time range. In nitrate solutions, only the fast formation process was observed. The slow formation process in nitric acid solutions was confirmed to be the reaction of OH radicals with undissociated nitric acid molecules, OH + HNO{sub 3} {yields} H{sub 2}O + NO{sub 3}, with a rate constant of (1.4 {plus minus} 0.1) {times} 10{sup 8} M{sup {minus}1} s{sup {minus}1}. The fast formation process is most probably the direct action of radiation on nitrate anion or nitric acid: NO{sub 3}{sup {minus}} (gamma radiation) {yields} e{sup {minus}} + NO{sub 3} or HNO{sub 3} (gamma radiation) {yields} HNO{sub 3}{sup +} + e{sup {minus}} {yields} NO{sub 3} + H{sup +} + e{sup {minus}}. The molar absorption coefficient of NO{sub 3} was evaluated as 1,300 {plus minus} 100 M{sup {minus}1} cm{sup {minus}1} at 640 nm. On the basis of this result, G values of NO{sub 3} weremore » evaluated in nitric acid, lithium nitrate, and sodium nitrate solutions. The main decay reaction of NO{sub 3} was proposed to be NO{sub 3} + NO{sub 2} {yields} N{sub 2}O{sub 5} in nitric acid solutions and its rate constant was evaluated as (1.7 {plus minus} 0.3) {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1}. Rate constants of reactions of NO{sub 3} with radiolytic products and some other compounds were obtained.« less

The conversion-time curves have been measured and treated quantitatively for the 60 Co-γ ray initiated inverse emulsion polymerization of aqueous sodium acrylate solutions on the basis of a monomer-droplet-nucleation mechanism. A method has been proposed to estimate the average number of polymerizing radicals in a droplet, n , that characterizes the polymerization kinetics. For the system studied under the experimental conditions, the value of n was derived as several hundreds, which is much larger than that for conventional emulsion polymerization.

The formation of nitrous acid has been studied in the 60Co-γ radiolysis of concentrated nitric acid solutions. The yields of nitrous acid are proportional to the electron fraction of nitric acid, on the basis of which, an additional reaction path, NO–3 [graphic omitted]→ O(3P)+ NO–2 with a primary yield of 0.16 µmol J–1, has been verified for the direct action of radiation on nitric acid.

A pulse radiolysis study on concentrated aqueous chlorate solution was carried out. In the radiolysis of the chlorate system, ClO 2 and ClO 3 radicals are produced as a result of direct action of radiation on chlorate ion with G values of 1.0 and 1.5, respectively, whereas the slow formation process of ClO 3 radicals is not observed. The absorption peak of ClO 3 radicals is around 330±10 nm and the absorption coefficient is evaluated as 4100 M -1 cm -1 . The rate constants of some reactions of ClO 3 radical with additives were determined

The Primary yields of water radiolysis have been evaluated as a function of nitric acid or nitrate concentration in the 60Co γ-radiolysis of nitric acid and 0.4 mol dm–3 sulfuric acid with nitric acid or sodium nitrate solutions containing CeIV and CeIII, in the presence and absence of Tl+. The radiolytic decomposition of water is significantly enhanced in these systems, from gw(–H2O)= 0.60 µmol J–1 for 0.4 mol dm–3 sulfuric acid–sodium nitrate solutions to gw(–H2O)= 0.76 µmol J–1 for nitric acid solutions at high solute concentrations.

In the pulse radiolysis of concentrated sulfuric acid solutions, the absorption spectrum and the molar absorption coefficient (1600 dm3 mol–1 cm–1) of the sulfate radical are unchanged up to 10 mol dm–3 H2SO4, suggesting that the sulfate radical exists in the dissociated form (SO–4). Two formation processes for the sulfate radical have been directly demonstrated in sulfuric acid and hydrogensulfate solutions: a fast one completed in the duration of the electron pulse, and a slow one occurring over a microsecond time range. For sulfate solutions only the fast formation process is observed. In sulfuric acid solutions the slow formation process is OH + HSO–4→ H2O + SO–4(4.7 × 105 dm3 mol–1 s–1) and OH + H2SO4→ HSO4+ H2O → SO–4+ H3O+(1.4 × 107 dm3 mol–1 s–1), and the fast formation process is the direct action of radiation on sulfuric acid with a G value of (2.7 ± 0.4)× 10–2 molecule eV–1. The yields of (OH + SO–4) and H can be quantified as: G(OH + SO–4)= 2.9fw+ 2.7fs and G(H)= 3.7fw+ 2.7fs. The yields of SO–4 have also been evaluated and the decay kinetics and reactions of the sulfate radical studied.

In the pulse radiolysis of concentrated phosphoric acid solutions, in the direct action on radiation on phosphoric acid gives rise to the phosphate radical. The yields of the phosphate radical and the hydroxyl radical are proportional, respectively, to the electron fractions of phosphoric acid and water, and can be quantified as G(˙OH + H2PO˙4)= 0.30fw+ 0.33fsµmol J–1. The forward and reverse rate constants of the equilibrium ˙OH + H3PO4⇄ H2O + H2PO˙4 were evaluated as 4.2 × 104 and 2.5 × 103 dm3 mol–1 s–1 respectively, from which E0(H2PO˙4, H+/H3PO4)= 2.65 V was derived. The decay kinetics and the reactions of the phosphate radical have also been studied.