Impact of γ-irradiation, CIPC treatment, and storage conditions on physicochemical and nutritional properties of potato starches

Gamma radiation as a modifier of starch – Physicochemical perspective

Starch is one of the most common and abundantly found carbohydrates in cereals, roots, legumes, and some fruits. It is a tasteless, colorless, and odorless source of energy that is present in the amyloplasts of plants. Native starch comprises amylose, a linear α-glucan having α-1,4-linkage and amylopectin, a branched polysaccharide with both α-1,4-linkage and α-1,6-linkage. Due to the low solubility, high viscosity, and unstable pasting property of native starch, it has been restricted from its application in industries. Although native starch has been widely used in various industries, modification of the same by various chemical, enzymatic and physical methods have been carried out to alter its properties for better performance in several industrial aspects. Physical modification like gamma radiation is frequently used as it is rapid, penetrates deeper, less toxic, and cost-effective. Starch when irradiated with gamma rays is observed to produce free radicals, generate sugars owing to cleavage of amylopectin branches, and exhibit variation in enzymatic digestion, amylose content, morphology, crystallinity, thermal property, and chemical composition. These physicochemical properties of the starch due to gamma radiation are assessed using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and its application are discussed.

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Assessment and comparison of morphological features of native and gamma-irradiated starch.

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Investigation of crystallinity and structural type of crystalline domains through XRD.

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FTIR spectroscopy confirmed the changes in chemical composition of gamma-irradiated and native starch.

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DSC analysis revealed the changes in gelatinization temperature of gamma-irradiated and native starch.

Effects of 1-MCP treatment on sprouting and preservation of ginger rhizomes during storage at room temperature

The purpose of this study was to explore the effects of 1-MCP on the sprouting and preservation of ginger rhizomes during storage at room temperature. Ginger rhizomes were treated with 1 µL L-1 1-methylcyclopropene (1-MCP) and stored at 23 ± 0.2 °C. Our data showed that application of 1-MCP reduced the rate of sprouting during storage compared with the control rhizome. Respiration rate and the reducing sugar content were also reduced following 1-MCP treatment, while the starch content increased. 1-MCP treatment increased the total phenol content and inhibited polyphenol oxidase (PPO) activity. 1-MCP treatment was also associated with a higher ascorbic acid content but a reduced crude fiber content. The generation of superoxide anion free radicals (O2-), hydrogen peroxide (H2O2) and malondialdehyde (MDA) was lower following 1-MCP treatment, while the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) were higher compared with the controls. These results suggested that application of 1-MCP could reduce sprouting rates, decrease the accumulation of ROS, and maintain the quality of ginger rhizomes during storage at room temperature. It would be useful to further explore the role and mechanisms of action of ethylene in regulating the sprouting of ginger rhizomes.

Lipid oxidation stability of ultra-high-temperature short-time sterilization sporoderm-broken pine pollen (UHT-PP) and 60 Co-irradiation sterilization sporoderm-broken pine pollen (60 Co-PP)

BACKGROUND

Pine pollen, a kind of Chinese traditional medicine, is rich in unsaturated fatty acids. During its processing, it is often needed to break the sporoderm in order to increase the availability of some ingredients, which can cause lipid oxidation and the development of rancidity during storage.

RESULTS

The primal peroxide value (PV) of ultra-high-temperature short-time sterilization sporoderm-broken pine pollen (UHT-PP) was much higher (over 15 times) than raw pine pollen (R-PP) and ⁶⁰ Co-irradiation sterilization sporoderm-broken pine pollen (⁶⁰ Co-PP). The PV of UHT-PP first increased and then decreased shortly after; however, PV of R-PP and ⁶⁰ Co-PP remained almost unchanged during storage. The volatiles associated with rancidity in UHT-PP were found to be significantly higher than ⁶⁰ Co-PP, especially hexanal (nearly 30 times) and hexanoic acid (about 2 times), and a multi-organoleptic sensor analyzer (electronic nose system) was able to differentiate these three kinds of samples when the output was subjected to discriminant function analysis. During storage (30 days), hexanal first increased and then decreased (at about 5 days), and hexanoic acid continuously increased for UHT-PP; however, no significant change was noted for R-PP or ⁶⁰ Co-PP. UHT-PP has a greater surface area than ⁶⁰ Co-PP, although same sporoderm-broken processes were applied. Antioxidants (flavone, carotenoid and tocopherols, sterol compounds) in ⁶⁰ Co-PP were significantly (P ≤ 0.05, by Duncan's multiple range test) higher than that in UHT-PP, although not significantly different for total phenolics.

CONCLUSIONS

Rancidity occurs more readily in UHT-PP than in R-PP and ⁶⁰ Co-PP during storage, probably because significant lipid oxidation and antioxidant degradation occurred during the UHT sterilization sporoderm-broken processing of pine pollen. © 2018 Society of Chemical Industry.

Physico-chemical and sensory evaluation of potato (Solanum tuberosum L.) after irradiation

ABSTRACT This work evaluated the effects of ionizing radiation on the physico-chemical and sensory characteristics of the potato cultivar Ágata (Solanum tuberosum L.), including budding and deterioration, with the end goal of increasing shelf life. For this, four groups of samples were harvested at the maturation stage. Three of them were separately exposed to a Co-60 source, receiving respective doses of 0.10, 0.15 and 2.00 kGy, while the non-irradiated group was kept as a control. All samples were stored for 35 days at 24 °C (± 2) and at 39% relative humidity. The following aspects were evaluated: budding, rot, loss of weight, texture, flesh color, moisture, external and internal appearance, aroma, soluble solids, titratable acidity, vitamin C, protein, starch and glucose. The results indicated that 0.15 kGy was the most effective dose to reduce sprouting and post-harvest losses, under the conditions studied.

Sprout suppression on potato: need to look beyond CIPC for more effective and safer alternatives

World over, potatoes are being stored at 8-12 °C (85-90 % RH). This is the most common way of long-term (up to 6 to 9 months) storage of potatoes. The benefit of storing the potatoes within the temperature range of 8-12 °C is minimum accumulation of sugars in stored potato tubers. In sub-temperate, sub-tropical and tropical countries of the world, short-term (3 to 4 months) storage of potatoes is being done by non-refrigerated traditional/on-farm methods. These short- and long-term storage methods keep the stored potatoes suitable not only for table purpose but also for processing. However, once the natural dormancy period of potato is over, the prevailing temperatures in these storage methods favour sprouting and sprout growth. Therefore, use of some sprout suppressant to check the sprout growth becomes essential under these methods of potato storage. CIPC [Isopropyl N-(3-chlorophenyl) carbamate] is the most wide spread and commonly used sprout suppressant on potatoes. CIPC has been in use for more than 50 years and research carried out over such a long period use of CIPC has not only enhanced our understanding of its properties and chemistry but also about the production and toxicological status of its metabolites/degradation products. Today, various safety issues and concerns have surfaced primarily due to continuous and long-term use of CIPC. This review presents an appraisal on CIPC and explains the reasons for the long-time dependence on this chemical as a potato sprout suppressant. Issues like maximum residue limit and acceptable daily intake limit are being discussed for CIPC. This article brings an update on practical aspects of potato storage, residue levels of CIPC, efficacy of CIPC as sprout suppressant and health and environmental safety issues linked with CIPC and its metabolites. The aim of this article is to find possible solutions, way outs and future plans that can make the sprout suppression of potatoes safer and more risk free.

Acrylamide mitigation strategies: critical appraisal of the FoodDrinkEurope toolbox

Not all the strategies proposed in FoodDrinkEurope toolbox have equal value in terms of efficacy and cost/benefit ratio.

Formation of resistant corn starches induced by gamma-irradiation

The effect of gamma-irradiation on formation of resistant starch (RS) in corn starch with different amylose content was examined. Normal corn starch, waxy corn starch, and high amylose corn starch (Hylon V and Hylon VII) were irradiated at 5, 10, 25 and 50 kGy. Gamma-irradiation at 5 kGy increased the amylose-like molecules in starches and thus significantly enhanced the RS content (p<0.05). Highest RS content was produced by 50 kGy irradiated in all the starch samples (p<0.05). The irradiation-induced RS was more evident in waxy corn starch, followed by high amylose corn starch and normal corn starch.