Physicochemical, thermal and pasting properties of starch separated from γ-irradiated and stored potatoes

Effect of gamma ray dose on granular and molecular structures of gamma ray-irradiated cassava starch and its application in bioplastics

In this study, the effect of gamma ray irradiation on the granular and molecular structures of cassava starch was examined. Cassava starch was irradiated with various gamma ray doses of 25, 50, 75, and 100 kGy. After irradiation, the starch turned yellow, but its granular morphological characteristics remained intact. However, the inner part and the 'Maltese cross' of the starch granules irradiated with 100 kGy were broken, and its crystallinity decreased considerably. The pH reduction (from 5.6 to 3.7) and carboxyl content increase (up to 0.38 %) confirmed the formation of carboxyl groups on the irradiated starch chains. Gamma ray irradiation caused glycosidic bond cleavages, resulting in shortened amylose chains and debranched amylopectin chains containing terminal carboxyl groups. The irradiated starches with different molecular weights have high potential for use in food and non-food applications, for example, in bioplastics. Thermoplastic-irradiated starch (TPIS) materials, and their blends with poly(lactic acid) (PLA) were prepared via extrusion. Both TPIS and PLA/TPIS blends exhibited considerably increased melt flow index values compared with those from the unirradiated starch at approximate increases of 420-2260% and 2-55%, respectively. The improved melt flow ability and reduced viscosity are advantages for some plastic conversion processes such as injection molding.

The Effect of Maltose on Structural, Physicochemical, and Digestive Properties of Lentil Starch under Electron Beam Irradiation

This study investigated the effects of electron beam irradiation (EBI) on the structural, physicochemical, and functional properties of lentil starch with varying maltose content. EBI did not significantly disrupt the starch's surface structure or cause amorphization of starch and maltose crystals, but it significantly reduced the intensity of starch's XRD peaks. The presence of maltose intensified internal growth ring damage, leading to more cross-link and rearrangement between short chains, improving short-range ordering of lentil starch and enhancing starch's solubility and thermal stability. Additionally, adding maltose that EBI then treats can lead to an increased content of slowly digestible starch in samples.

Investigation of the role of sodium chloride on wheat starch multi-structure, physicochemical and digestibility properties during X-ray irradiation

In this paper, different NaCl content was added to wheat starch and then subjected to X-ray irradiation to investigate the effect of salt on starch modification by irradiation. The results showed that the degradation of wheat starch intensified with the increase in irradiation dose. When irradiated at the same dose, wheat starch with sodium chloride produced shorter chains, lower molecular weight and amylose content, and higher crystallinity, solubility, and resistant starch than wheat starch without sodium chloride. The energy generated by X-rays dissociating sodium chloride caused damage to the glycoside bonds of the starch molecule. With a further increase in the mass fraction of NaCl, the hydrogen bonds of the starch molecules were broken, and the double helix structure was depolymerized, which exacerbated the extent of irradiation-modified wheat starch. At the same time, starch molecules will be rearranged to form a more stable structure.

Comparative investigation of the effects of electron beam and X-ray irradiation on potato starch: Structure and functional properties

Electron beam (particle radiation) and X-ray (electromagnetic radiation) without radioisotope in the application of material modification have received increasing attention in the last decade. To clarify the effect of electron beam and X-ray on the morphology, crystalline structure and functional properties of starch, potato starch was irradiated using electron beam and X-ray at 2, 5, 10, 20 and 30 kGy, respectively. Electron beam and X-ray treatment increased the amylose content of starch. The surface morphology of starch did not change at lower doses (< 5 kGy), but starch granules were aggregated with the increase of doses. All treatments decreased crystallinity, viscosity and swelling power but increased solubility and stability properties. The effects of electron beam and X-ray on the starch had a similar trend. Unlike X-ray, electron beam destructed the crystallinity of starch to a lesser extent, thereby increasing thermal stability and freeze-thaw stability. Furthermore, X-ray irradiation at higher doses (> 10 kGy) resulted in outstanding anti-retrogradation properties of starch compared with electron beam treatment. Thus, particle and electromagnetic irradiation displayed an excellent ability to modify starch with respective specific characteristics, which expands the potential application of these irradiations in the starch industry.

Starch parameters and short-term temperature fluctuations - Important but not yet in focus?

Plants are regularly challenged by unfavorable environmental conditions. As climate change continues, adverse situations such as drought, heat, and cold are expected to increase and become more severe. Most starchy crops are affected by such stresses. In recent years, researchers have made many new discoveries about starch metabolism in general and also on granule structure, including effects on starch following longer-term temperature stresses. However, in this study, we focus on short-term temperature stress on storage starch granule properties. Here our knowledge is less and it is likely that also short-term temperature stresses can affect various starch parameters. Therefore, we see a need for this type of analysis and discuss the matter in more detail and we conclude that a deeper knowledge particularly of starch granule parameters could allow targeted breeding of cultivars that exhibit different starch characteristics as a result of short-term stress. For these reasons, we are convinced that more comprehensive research on the effects of short-term temperature stress on starch granule characteristics is important, necessary, and timely.

Effect of Single and Dual Modifications on Properties of Lotus Rhizome Starch Modified by Microwave and γ-Irradiation: A Comparative Study

A comparative study between two novel starch modification technologies, i.e., microwave (MI) and γ-irradiation (IR), is of important significance for their applications. The objective of this work is to compare the changes in lotus rhizome starch (LRS) subjected to single modifications by MI (thermal treatment) and IR (non-thermal treatment), and dual modification by changing the treatment sequence, i.e., microwave followed by irradiation (MI-IR) and irradiation followed by microwave (IR-MI). The amylose content of native and modified LRS varied from 14.68 to 18.94%, the highest and lowest values found for native and MI-LRS, respectively. IR-treated LRS showed the lowest swelling power (4.13 g/g) but highest solubility (86.9%) among native and modified LRS. An increase in light transmittance value suggested a lower retrogradation rate for dual-modified starches, making them more suitable for food application at refrigeration and frozen temperatures. Dual-modified LRS showed the development of fissures and dents on the surface of granules as well as the reduction in peak intensities of OH and CH2 groups in FTIR spectra. Combined modifications (MI and IR) reduced values of pasting parameters and gelatinization properties compared to native and microwaved LRS and showed improved stability to shear thinning during cooking and thermal processing. The sequence of modification also affected the rheological properties; the G′ and G″ of MI-IR LRS were lower (357.41 Pa and 50.16 Pa, respectively) than the IR-MI sample (511.96 Pa and 70.09 Pa, respectively), giving it a soft gel texture. Nevertheless, dual modification of LRS by combining MI and IR made more significant changes in starch characteristics than single modifications.

Effects of single and dual modifications through electron beam irradiation and hydroxypropylation on physicochemical properties of potato and corn starches

In this study, electron beam irradiation (EBI; 2, 4, 6, 8 and 10 kGy), hydroxypropylation (HP) and dual modification of EBI-HP were applied to modify corn and potato starches. The results showed that the molar substitution (MS) of EBI-HP modified corn and potato starches were in the range of 0.060-0.087 and 0.080-0.124, respectively. After modifications, amylose content of corn (30.0 %) and potato (31.2 %) starches were declined to 24.2-28.1 % and 26.1-29.5 %, respectively, and relative crystallinity was reduced from 35.5 to 30.0 % for corn and 34.1 to 20.2 % for potato. Pasting properties decreased significantly in both starch sources with increasing irradiation dose. EBI decreased springiness, enthalpy of retrograded starch (ΔHr) and percentage of retrogradation (R%) on corn starches, which were different from those effects observed on potato starches. Meanwhile, HP increased peak viscosity up to 312.6 RVU and 1359.3 RVU for corn and potato starches, respectively. Moreover, EBI-HP was highly responsible for the decreases in the textural, gelatinization and retrogradation properties and relative crystallinity in both corn and potato starches. These results enhance the understanding of starch functionality modified by using both physical and chemical methods, and provide further insights on food and non-food applications.

The protective effect of exogenous salicylic and gallic acids ameliorates the adverse effects of ionizing radiation stress in wheat seedlings by modulating the antioxidant defence system

Plant growth regulatory substances play a significant role in maintaining developmental and physiological processes in plants under abiotic stress. Apart from traditional plant hormones, the phenolic acids, salicylic acid (SA) and gallic acid (GaA), are emerging players with pivotal roles in alleviating various environmental perturbations. The present study compared the stress alleviation effect of these two phenolic acids in wheat (Triticum aestivum L. 'Gönen-98') seedling whose seeds were used in this study pre-treated with increasing doses of gamma irradiation (IR, 100 > 400 Gy). Leaves from seedlings hydroponically grown for 10 days in medium containing 100 μmol/l SA and GaA were used in the measurements and determinations. Accordingly, exogenous treatment with SA and GaA significantly improved plant growth and photosynthetic activity and regulated stress-induced osmolyte accumulation against γ-irradiation. Treatments also led to significant reductions in TBARS and H₂O₂ contents. Antioxidant enzyme activities were further stimulated by SA and GaA treatment in comparison to IR alone. The phenolic pool including phenolic acids and GSH content in whole seedlings were promoted by IR and further SA and GaA applications. Contents in phenolic acids liberated from soluble free, soluble ester-conjugated and soluble glycoside-conjugated SA and GaA contents in roots and leaves increased following SA and GaA treatments alone in comparison to the control and IR groups. The present results indicate that SA and GaA can alleviate the ameliorative effects of IR, leading to further oxidative stress, and can improve the tolerance of stressed wheat seedlings by stimulating enzymatic and non-enzymatic antioxidant defence system components.

Effect of heat treatment and γ-irradiation on pasting, rheological, and fungal load of whole and dehulled millets

Millets are important food crops in food systems and application of physical treatments could improve the functional properties of millet-based products. Therefore, we investigated the effect of heat and γ-irradiation treatments on the pasting, rheological, and microbial load of whole and dehulled millets (sorghum, foxtail millet, and pearl millet). Moreover, similarity in treatment effect was evaluated by principal component analysis (PCA). The results revealed the significant (p < 0.05) decrease in pasting properties of whole and dehulled millets, except for pasting temperature (71.03 to 74.88 °C). Likewise, significantly (p < 0.05) decreased tendency was observed for all rheological properties, except for phase angle (0.05 to 0.30°) and yield point (13 to 5089). Samples showed a significant (p < 0.05) reduction in fungal growth (89.75 × 10⁴ to 4.46 × 10⁴ CFU/g) compared to control (110.30 × 10⁴ CFU/g). Moreover, samples individually formed 3 clusters (clusters 1: sorghum, 2: pearl millet, and 3: foxtail millet) based on pasting properties, which was confirmed by PCA. Therefore, the findings concluded that the effect of heat and γ-irradiation would be necessary to decrease pasting, rheological, and no microbial growth characteristics of dehulled and whole millets for the development of specific millet-based food products.

Effects of electron beam irradiation on the properties of waxy maize starch and its films

Waxy maize starch was irradiated under different doses of radiation (2-30 kGy), and starch physicochemical properties were analysed. Films were subsequently produced from native and irradiated waxy maize starches and their properties were tested. The starch molecular weight markedly decreased with increasing irradiation dose. And the branch chain length, melting temperature, melting enthalpy, and relative crystallinity decreased slightly, especially at an irradiation dose below 15 kGy. This indicated that more α-1,6-glucosidic bonds than α-1,4-glucosidic bonds were cleaved by a low dose of irradiation; hence, more linear chains were released. Films prepared from 10 kGy irradiated waxy maize starch displayed enhanced mechanical properties and increased solubility, owing to a moderate increase in linear starch chains and a decrease in starch molecular weight, respectively. The resulting rapidly-dissolvable films from irradiated waxy maize starch have potential for use in instant food packaging.

Impact of γ-irradiation on physicochemical characteristics, lipoxygenase activity and antioxidant properties of finger millet

In the present study, the finger millet grains were subjected to γ-irradiation at four different dosage levels: 2, 5, 10, and 15 kGy. Effect of γ-irradiation on the proximate composition, pasting properties, lipoxygenase activity, and antioxidant properties of finger millet flour was evaluated. Moisture, protein, fat, ash, and carbohydrate content of native flour was 12.96, 6.85, 2.73, 1.57, and 73.69 g/100 g, respectively. According to the results of proximate analysis, γ-irradiation significantly (p < 0.05) reduced the moisture contents and increased protein contents; however, the fat content of the irradiated flour was equal to or lower than that of the native flour. Pasting properties of the finger millet flour was reduced with the γ-irradiation. Compared with the native flour, lipoxygenase activity and malondialdehyde content decreased and radical scavenging activity, catalase, and superoxide dismutase activities increased in the irradiated flour with increasing γ-irradiation doses. Finally, the present study suggested that the γ-irradiation process improved the antioxidant enzymes and physicochemical characteristics; which could be helpful in formulating tailored made food products.

Synthesis of carboxymethylcellulose/starch superabsorbent hydrogels by gamma-irradiation

Background

Superabsorbent hydrogels show a large potential in a wide array of applications due to their unique properties. Carboxymethylcellulose (CMC) is a commercially available water-soluble cellulose derivative of major interest in the hydrogel synthesis. High-energy irradiation allows the chemical crosslinking without the use of crosslinking agents, while the introduction of other natural or synthetic polymers offers a convenient way to modify the gels. In this study we examined the effect of the addition of starch, a low-cost renewable polysaccharide, on the properties of carboxymethylcellulose-based hydrogels.

Results

Superabsorbent gels were prepared by gamma irradiation from aqueous mixtures of carboxymethylcellulose and starch. The partial replacement of CMC with starch improved the gel fraction, while a slight increase in the water uptake was also observed. However, very high starch content had a negative impact on the gelation, resulting in a decrease in gel fraction. Moreover, higher solute concentrations were preferred for the gelation of CMC/starch than for pure CMC. Hydrogels containing 30% starch showed the best properties: a water uptake of ~350 g_water/g_gel was achieved with ~55% gel fraction synthesized from 15 w/w% solutions at 20 kGy. Heterogeneous gel structure was observed: the starch granules and fragments were dispersed in the CMC matrix. The swelling of CMC/starch gels showed a high sensitivity to the ionic strength in water due to the CMC component. However, the mixed gels are less sensitive to the ionic strength than pure CMC gels.

Conclusions

The introduction of starch to carboxymethylcellulose systems led to improved properties. Such gels showed higher water uptake, especially in an environment with high electrolyte concentration. CMC/starch hydrogels may offer a cheaper, superior alternative compared to pure cellulose derivative-based gels depending on the application.

Gamma irradiation induced modification of bean polysaccharides: impact on physicochemical, morphological and antioxidant properties

In the present study starches from four bean varieties viz. red, yellow, black and white, were gamma irradiated in the dose range of 5-25 kGy to investigate the effect of radiation processing on physicochemical, morphological and antioxidant properties. Studies revealed positive correlation between gamma irradiation and solubility (r=0.91), irradiation and water absorption capacity (r=0.82) and negative correlations between irradiation and swelling power (r=-0.92), irradiation and pasting properties (r=-0.91) and irradiation and thermal properties (r=-0.89). Microscopic observation under scanning electron microscope indicated the development of surface cracking and fractures on the surface of starch granules with increase in dose. X-ray diffractometry revealed no significant change in diffraction patterns between control and irradiated starches, except a decrease in relative crystallinity. Irradiation increased the proportions of both rapidly digestible starch and enzyme resistant starch of bean starches and significantly prevented the retrogradation of bean starches during storage. Results of the DPPH radical scavenging activity and ferric reducing power indicated significant (p≤0.05) increase in antioxidant activity of all irradiated bean starches with increase in dose.

Impact of post-harvest radiation treatment timing on shelf life and quality characteristics of potatoes

The effects of gamma radiation treatment (50 and 100 Gy) on potato tubers irradiated at different days (10th, 30th and 50th) after harvest were studied during 5 months of storage at 10°C using Agria and Marfona varieties. A factorial experiment was done, based on a Randomized Complete Block Design with four replications. The 100 Gy radiation treatments on 10th and 30th days after harvest completely prevented sprouting at both varieties studied but on 50th day only Agria tubers not sprouted. This study indicated that early irradiation and absorbed radiation doses significantly decreased sprouting, percent weight loss and specific gravity of tubers. Reducing sugar content significantly increased by delay in irradiation and lower dose of radiation while non-reducing sugars did not decrease significantly by delay in irradiation and higher dose of radiation. The least increase in reducing sugars (10.2%) and most decrease in non-reducing sugar (-12.75%) were observed in tubers that irradiated on 10th day after harvest. The content of ascorbic acid was decreased by irradiation with higher dose. Although delay in irradiation caused less loss of ascorbic acid (8.5%) but showed greater metabolic changes as sprouting, weight loss, firmness, and sugars contents. Also, more increased delay in irradiation needed higher radiation doses for sprout inhibition.

Physico-chemical and pasting properties of starch from stored potato tubers

Starch was separated from tubers of four potato (Solanum tuberosum L.) cultivars, viz. 'Kufri Jyoti', 'Kufri Sindhuri', 'Kufri Chipsona-1' and 'Kufri Chipsona-2' before and after 90 days of storage at 4, 8, 12 and 16°C and, morphological, physico-chemical and pasting properties were studied. Scanning electron microscopy showed oval and irregular shaped starch granules with average diameter of 15 μm, and the granule diameter increased after storage. Peak viscosity was lower after storage at 8°C and higher at 16°C. Hot paste viscosity decreased while breakdown viscosity and set back viscosity increased after storage, and there was no significant change in cold paste viscosity. A significant decrease in pasting time and increase in pasting temperature was observed after storage. Phosphorus content showed significant positive correlation with peak viscosity (r = 0.452, p <0.05) and breakdown viscosity (r = 0.685, p <0.01), and a negative correlation with amylose content (r = -0.674, p <0.01). 'Kufri Sindhuri' starch showed significantly (p <0.05) higher peak, hot paste, breakdown and cold paste viscosity. The X-ray diffraction pattern of starch showed a distinctive maximum peak at around 17°, 2 ϑ and it was not affected by the cultivar or storage temperature.