**5. Effect of pre-storage treatment and storage conditions on quality of root vegetables**

Freshly harvested root vegetables deteriorate over a short period of time if not handled appropriately. Several morphological, biochemical, and physiological changes that are essential to the root tissue occur. For example, increased respiration rate, moisture loss and desiccation, spoilage caused by fungi and bacteria, earthy odors and flavors, sprouting and development of white blush on damaged surfaces, softening of tissues, color changes resulting from the synthesis of new pigments and destruction of others, and changes in the phytochemical and nutritional composition. Most of these changes are temperature-dependent.

Postharvest quality changes in carrot includes weight loss, bitterness, bacterial deterioration, rooting, and sprouting. The carrot has low metabolic activity at low temperatures, and can be stored for 6–8 months without loss of quality under optimal storage conditions of 0°C temperature and 98% RH [45]. **Table 1** provides a summary of some quality changes that occur in root vegetables when exposed to varied prestorage treatments. Post-harvest hot-water treatment (50*°*C for 1 min) can be used for preserving their β-carotene and vitamin C content, although for carrots not destined for storage (**Table 1**) [45]. Pre-storage treatment involving carrot exposure to Ozone atmosphere 50± 10 nL/L treatment at 0.5°C and ≥95% RH recorded reduced severity of watery soft rot and gray mold fungal diseases, and blotches of discolored brown periderm tissue after a storage period of 180 days [56]. Similarly, reduced severity of fungal watery soft rot disease was observed on carrots that were exposed to 5 s prestorage treatment of steam under 0.2 MPa pressure and 70°C prior to storage at 0.5°C for 60 days, and an additional 14 days at 20°C [46]. A UV-C (0.88 kJ/m2) treatment of carrot at 10°C and 90% RH resulted in reduced severity of watery soft rot and gray mold fungal diseases on carrots stored for 15 days (**Table 1**) [67].

Generally, when plants are subjected to postharvest abiotic stresses they synthesize secondary metabolites, such as phenolic compounds. **Table 2** summarizes the effect that different storage systems on root vegetables.

In a study where carrots were stored for 48 h at 20°C, a significant increase in the phenolic content was found [79]. In [76], study results showed that when black carrots were stored at 4°C retained a high level (53.4–81.0%) of anthocyanins than samples stored at 25°C for 20 weeks (7.8–69.3%). Similarly, in a study that investigated the effect of controlled atmosphere on baby carrots revealed that that controlled atmosphere of 5 kPa O2 and 5 kPa CO2 significantly increased the phenolic content, particularly chlorogenic acid [74]. Slight variations in α- or β-carotene have been demonstrated when carrots were stored at 0°C for 6 months [93]. According to Imsic


*Phytochemical Changes in Root Vegetables during Postharvest Storage DOI: http://dx.doi.org/10.5772/intechopen.106554*

*d: days of storage; EC: edible coating (carboxy methyl cellulous and cellophane); PW: paraffin wax; FT: fungicide treatment; HPP: hydrogen peroxide plus; GI: gamma irradiation (0, 50, 100, and 150 Gy); HWT: hot water treatment; ST: steam treatment; min: minute; RH: relative humidity; and UV-C: ultra violet light (intensities 0.0, 3.4, 7.1, 10.5, and 13.6 kJ m−2).*

#### **Table 1.**

*Summary of studies on effects of pre-storage treatments on the quality of selected root vegetables.*

et al. [77], storing carrots at either 4°C or 20°C resulted in increases in (all-*E*)-βcarotene of 20.3% after 3 days at 4°C and 34.4% after 14 days at 20°C, respectively. In contrast, another study [80] reported that β-carotene contents were reduced after 8 days of storage at different temperatures, by 46% (7.5–8.5°C), 51% (17–21°C), and 70% (22–37.5°C). Significantly high concentrations of polyacetylenes (falcarinol, falcarindiol, and falcarindiol-3-acetate) were documented in whole carrots that were refrigerated for 4 months at 1°C [75]. This indicates that polyacetylenes were produced during postharvest storage or there was little degradation in intact carrots after cold storage [75]. In a separate study [76], the level of vitamin C in baby carrots reduced during cold storage in high and moderate O2 conditions but under a low O2 atmosphere, baby carrots retained the highest amount of vitamin C. Freezing also has a negative impact on vitamin C content of carrots as in [78] where a decrease of 4.1% was recorded. Also, prolonged storage duration has been shown to lower the concentration of vitamin C from 15 to 49% [94]. Similarly, Kjellenberg et al. [95] noted that during storage, there is a decrease of glucose and fructose and a development of polyacetylenes, which causes a reduction of soluble sugars. The decreased


#### *Advances in Root Vegetables Research*

