Effect of irradiation on vitamin C content of strawberries and potatoes in combination with storage and with further cooking in potatoes

Abstract

The vitamin C content of four varieties of strawberry was determined before and after treatment with ionising radiation at doses of 1, 2 or 3 kGy and after storage for 5 and 10 days at 6°C, and also in potatoes which, having been allowed a period of one month to recover from the effects of post‐harvest stress, were irradiated at a sprout inhibition dose of 0·15 kGy, followed by storage and cooking. Total ascorbic acid (TAA), ascorbic acid (AA) and dehydroascorbic acid (DHAA) concentrations were measured using the technique of ion‐exclusion high‐performance liquid chromatography. Results from analysis of the strawberry samples showed the DHAA content increased immediately following irradiation and must, therefore, be taken into account when reporting vitamin C levels in irradiated produce. In addition it was observed that whilst irradiation did affect the vitamin C concentration in all varieties of strawberry, the change was small in comparison with the large variations observed between varieties. With regard to potatoes results showed that, whilst irradiation, storage and cooking all had the effect of reducing vitamin C concentration, irradiated samples stored for 5 months had similar or marginally higher levels than their non‐irradiated counterparts. Cooking did not markedly reduce TAA content of irradiated potatoes compared to non‐irradiated potatoes and it was also noted that microwave cooking was more destructive than boiling in lightly salted water. ©1997 SCI

Effects of gamma irradiation on the microbiological, nutritional, and sensory properties of fresh vegetable juice

“…Ascorbic acid and dehydroascorbic acid were analyzed using modifications of the method of Graham and Stevenson (1997). The juice (5 ml) was homogenized for 3 min with an equal volume of 2.5% metaphosphoric acid and was centrifuged for 5 min at 6500g.…”

“…The decrease observed in the total ascorbic acid was less than that of the ascorbic acid due to the amount of dehydroascorbic acid which may converted from ascorbic acid. This result was similar to the results from the analysis of potato samples which showed that the dehydroascorbic acid content increased immediately following irradiation (Graham & Stevenson, 1997). During the storage period, total ascorbic acid, ascorbic acid, and dehydroascorbic acid contents were reduced (P < 0.05), and the ascorbic acid of the irradiated carrot and kale juice were higher than that of the non-irradiated at 3 days of storage.…”

Preharvest and postharvest factors influencing vitamin C content of horticultural crops

“…In general doses of 2-3 kGy combined with refrigeration were useful for extending the shelflife of strawberries (Graham and Stevenson, 1997). During storage AA levels significantly intrimming of leafy vegetables results in loss of outer green leaves which contain more vitamins than inner leaves.…”

“…Dehydrated pineapples and guava pretreated with cysteine hydrochloride had increased AA retention and reduced color change during storage (Mohamed et al, 1993). Table 7 Effect of irradiation dose and storage on the total AA (TAA), reduced AA (RAA), and DHA concentrations (mg/100g FW) of strawberry (Graham and Stevenson, 1997) Table 8 AA content (mg/100g FW) of apples (Zubeckis, 1962) (Table 9). The total vitamin C was 8, 13, or 21% lower than initial values in slices kept for 6 days at 0, 5, or 10°C, respectively (Agar et al, 1999).…”

Effect of Irradiation on Total Phenol and Catechins Contents and Radical Scavenging Activity of Green Tea Leaf and Stem Extract

“…The AACs were determined according to the method of Graham and Stevenson (1997). The green tea (1 mL, 1 mg/mL) was centrifuged at 10,000 × g for 10 min and the supernatants (0.5 mL) were mixed with 2 mL of trichloroacetic acid (5%), after which the mixtures were centrifuged at 15,000 × g for 10 min (4C).…”