Impact of Electron Beam Irradiation on Fatty Acid Profile of Canavalia Seeds

Comparison of low energy and high energy electron beam treatments on sensory and chemical properties of seeds

Consumption of fresh and minimally processed foods such as seeds as a part of a healthy diet is a trend. Unfortunately, fat-rich seeds are often contaminated with pathogenic microorganisms and face frequent product recalls. Electron beams have been applied as a microbial decontamination measure for decades. Conventionally high energy electron beams (HEEB) are being used, whereas low energy electron beams (LEEB, <300 keV) have only recently been introduced to the food industry and more studies are needed. Electron beam treatment has several advantages over other decontamination technologies. The treatment is non-thermal, chemical-free, water-free, and does not use radioactive substances. The effect of electron beams on the sensory and chemical properties of seeds has not been widely studied. This study assessed LEEB and HEEB treated pumpkin and flax seeds immediately after treatments, and after three months of storage. The seeds' sensory profiles were altered after both treatments when compared with non-treated samples, with a higher dose leading to a greater level of alteration. However, the sensory profile of LEEB treated seeds was similar to the non-treated seeds whereas HEEB treated seeds differed from both. The storage period of three months further increased the observed differences between the samples. LEEB and HEEB treatments seemed to cause lipid degradation as the content of volatile aldehydes was increased. This effect was more profound in HEEB treated samples. The data presented in this study shows that LEEB as a microbial reduction solution has great potential to preserve the chemical and sensory properties of nutritious seeds.

Effect of high energy electron beam on proteolysis and antioxidant activity of rice proteins

This research focused on the effects of electron beam irradiation (EBI) on the hydrolysis and antioxidant activity of rice proteins (RPs). The RPs were treated with 0, 5, 10, 20 and 30 kGy doses of EBI. The results showed that EBI pretreatment improved significantly (P < 0.05) the degree of hydrolysis, increasing the DH value by more than 15.09% at a dose of 30 kGy. In addition, radical scavenging results showed that EBI treatment had effects on antioxidant activity and could increase the DPPH and ABTS+ radical scavenging activity of rice protein hydrolysates (RPHs) by 32.06% and 79.11%, respectively (30 kGy). The CAA test also confirmed that EBI pretreatment could effectively improve the ability of RPHs to remove intracellular free radicals. Scanning electron microscopy indicated that EBI treatment destroyed microstructures and resulted in cracks and fragments of RPs. Circular dichroism analysis showed that EBI affected the secondary structure of RPs by destroying the α-helix structure. Changes in the UV visible spectra indicated unfolding of RPs by EBI. Amino acid and molecular weight distribution analysis revealed that EBI pretreatment could increase the ratio of antioxidant-related amino acids and produce smaller peptides. Therefore, EBI pretreatment is an efficient method to promote protein proteolysis due to its effect on the molecular conformation as well as on protein microstructure. Moreover, EBI treatment applied before enzymatic hydrolysis has the potential to prepare hydrolysates with high bioactivity.

Impact of Electron Beam Irradiation on the Bioactive Principles of Seeds of Coastal Sand Dune Wild Legumes (Canavalia spp.)

BACKGROUND

Recent patents reveal that vegetable ingredients have several applications in novel food formulations. Many so-called antinutritional components (e.g. tannins, saponins, lectins and protease inhibitors) have nutraceutical as well as pharmaceutical significance. Seeds of two wild legumes of the genus Canavalia inhabitants of the coastal sand dunes of Southwest India are known for a variety of bioactive principles (e.g. phenolics, tannins, canavanine, concanavalin and phytohemagglutinins).

OBJECTIVE

This study evaluates the impact of Electron Beam (EB) irradiation on the bioactive components of seeds of two coastal sand dune wild legumes Canavalia cathartica and C. maritima.

METHODS

The dry seeds of C. cathartica and C. maritima were EB irradiated with different doses (2.5, 5, 10 and 15 kGy) to follow changes in six bioactive principles (total phenolics, orthodihydric phenols, tannins, canavanine, trypsin inhibitors and phytohemagglutinins) in comparison to control seeds. One-way ANOVA was employed to follow the variation in bioactive components of seeds in control and different doses of irradiation.

RESULTS

Seeds of both legumes were devoid of orthodihydric phenols and trypsin inhibitors. In C. cathartica, the total phenolics showed significant dose-dependent increase up to 5 kGy and decreased thereafter. Tannin content was not altered up to 10 kGy followed by significant decrease at 15 kGy. There was no significant change in canavanine content and the phytohemagglutinin activity against human erythrocytes was not altered. Seeds of C. maritima did not show significant changes in total phenolics as well as tannin contents. The content of canavanine showed significant dose-dependent increase up to 5 kGy followed by significant decrease. There was no variation in phytohemagglutinin activity against erythrocytes A, B and O, while against AB, the activity decreased at 2.5 kGy and further decrease was constant at higher doses.

CONCLUSION

The EB irradiation doses employed have selectively altered the bioactive principles of Canavalia seeds and such treatments may facilitate to maneuver desired medicinal, nutritional, functional and cooking properties. Besides selective changes in bioactive components the seeds have extended shelf life.

Effect of electron beam irradiation on the structural characteristics and functional properties of rice proteins

A study of the structural and functional changes of rice proteins (RPs) induced by electron beam irradiation (EBI) at 5 kGy, 10 kGy, 20 kGy, and 30 kGy was performed. The microcosmic surface structures of the RPs were changed and fragmented due to irradiation damage occurring on the RP surfaces. The changes in the UV visible spectra, intrinsic fluorescence spectra, surface hydrophobicity and SH and SS group contents indicated that the RPs unfolded after EBI treatment. In addition, the degree of conformational change was increased with increasing EBI treatment doses. FTIR analysis showed that the secondary structure redistributed, showing decreases in α-helices and concomitant increases in β-sheets, β-turns and random coils. The functional properties, emulsifying abilities, water adsorption capacities and oil adsorption capacities of the irradiated RPs improved dose-dependently, with maximums occurring at 30 kGy. The foaming properties were also enhanced by EBI; however, this effect was not dose-dependent. In contrast, all of the samples irradiated by electron beams presented lower emulsion stability than the control (0 kGy). These results provide a theoretical basis for the application of EBI in improving protein properties in the future.

A study of the structural and functional changes of rice proteins (RPs) induced by electron beam irradiation (EBI) at 5 kGy, 10 kGy, 20 kGy, and 30 kGy was performed.

How does electron beam irradiation dose affect the chemical and antioxidant profiles of wild dried Amanita mushrooms?

As with all mushrooms, Amanita species demonstrates several conservation problems, due to a post-harvest life limited to a few days. Drying is one of the most commonly used methods in mushroom preservation. Food irradiation is another possible way to improve food quality and insure its security. Among the emerging irradiation technologies, electron beam irradiation has wide applications, allowing for high throughput, wide flexibility and potential, without any negative effect on the environment. The effects of different electron beam irradiation doses in Amanita genus, were assessed by measuring the changes produced on a wide variety of nutritional, chemical and antioxidant indicators. The evaluated profiles indicated differences between non-irradiated and irradiated samples, however a high similarity was observed among different doses. This finding advises that the highest assayed dose (10 kGy) be applied, ensuring a higher effectiveness from a decontamination and disinfestation perspective, without having any stronger effects than those observed by the lower doses.