Effect of sulphur dioxide and blanching on the stability of carotenoids of dehydrated carrot

Abstract

The influence of blanching and sulphiting of carrot on the stability of carotenoids of dehydrated carrot was evaluated. The carotenoid content of untreated and treated carrots was measured after dehydration and during storage of dehydrated carrot at 37°C. Sulphiting was found to have a marked effect on the stability of carotenoids of both unblanched and blanched carrots during dehydration and storage at 37°C. The effectiveness of sulphur dioxide was reduced by increasing blanching time to over 1 min, the period in which the carrot becomes just adequately blanched. Even 9621 pg g-I SO, in over-blanched carrot was not as effective as less than one-quarter of this concentration in carrot that had been just adequately blanched. The combination of sulphiting, and blanching to a level sufficient to inactivate peroxidase activity, is considered to be the most effective method for enhancing the storage life of the product, and optimisation of the blanching process is highly desirable in order to gain the maximum benefit from the SO, treatment.

Kinetics of colour changes in dehydrated carrots

“…Blanching prior to dehydration of carrots enhanced the stability of carotenoids during storage. This is consistent with the findings of Arya et al (1982), Baloch (1987) and Zhao and Chang (1995).…”

“…Several researchers have studied the effect of drying on carrot quality (Doymaz, 2004;Lin et al, 1998;Mazza, 1983;Park, 1987;Prakash et al, 2004;Schadle, Burns, & Talley, 1983;Sumnu, Turabi, & Ö ztop, 2005). However, the literature contains few references on the retention of b-carotene and colour stability in dehydrated carrots during storage (Baloch et al, 1973;Baloch, 1987;Negi & Roy, 2001). Kinetic parameters including reaction order, rate constant and activation energy are essential to predict the quality of foods.…”

Effect of treatments and packaging on the quality of dried carrot slices during storage

“…Reduced rate of carotenoids destruction in sulphite treated carrot was reported by Arya et al (1979) and Zhao and Chang (1995). Baloch et al (1987) also reported that SO 2 showed a protective effect on the carotenoids of the blanched carrot and effectiveness of SO 2 increased with increase in SO 2 content. There was a significant (p≤0.05) reduction in the β-carotene content of carrot slices during storage.…”

“…Baloch et al (1981) found that dipping in solution of sodium bisulfite improved the reconstitution of the dried carrots. Rehydration ratio was more in dried slices packed in AFL pouches as compared to those packed in HDPE pouches due to less moisture content in product.…”

“…18.3 and 22.1 respectively. Baloch et al (1981) found that dipping in solution of sodium bisulfite improved the color of the dried carrots. During storage, the a values were found to vary from 25.4 (initially) to 19.0 (after 6 months).…”