Accumulation of Phenolic Acids during Storage over Differently Handled Fresh Carrots

Abstract

Carrots contain a significant content of phenolic compounds, mainly phenolic acids. Technological processing of carrots inflicts wounding stress and induces accumulation of these compounds, especially caffeic acid derivatives, in the periderm tissue. In this study, the effect of minimal processing (polishing, washing, peeling, and grating) on the retention of soluble phenolic acids in carrots was monitored during cold storage. Storage for up to 4 weeks and 24 h was used for whole and grated carrot samples, respectively. Total phenolic acid levels found in differently processed carrots varied greatly at the beginning of the storage period and on dry weight basis they ranged from 228 ± 67.9 mg/kg (grated carrot) to 996 ± 177 mg/kg (machine washed). In each case, processing followed by storage induced phenolic acid accumulation in the carrots. At the end of the experiment (4 weeks at +8 °C), untreated and machine-washed carrots contained ca. 4-fold more phenolic acids than at day 0. Similarly, polished carrots contained 9-fold and peeled carrots 31-fold more phenolic acids than at day 0. The phenolic acid content in grated carrot doubled after 24 h storage at +4 °C. Individual phenolic acids were characterized by high resolution mass spectrometry. MS data strongly suggest the presence of daucic acid conjugates of phenolic acids in carrot. Storage time did not have statistically similar effect on all compounds and generally in a way that dicaffeoyldaucic acid had the highest increase. This research provides important information for primary production, packaging, catering, the fresh-cut industry and consumers regarding the selection of healthier minimally processed carrots.

Peeling Affects the Nutritional Properties of Carrot Genotypes

“…The exclusive occurrence of hydroxycinnamic acids was confirmed for carrots grown in the arenili ( Table 6 ; Figure 1 ). In terms of qualitative profile, the phenolic compounds were in line with those observed in many studies on carrot reporting chlorogenic acid as prevalent [ 10 , 11 , 20 , 41 ], so it substantially affected the total phenolic acid concentration changes observed between varieties in both root portions.…”

“…Their assumption can result in many beneficial effects on human health by contrasting the occurrence of cardiovascular diseases, cancers, and neurodegenerative diseases [ 50 ]. The predominant phenolic compounds in carrots are reported to be phenolic acids [ 10 , 50 , 51 ], which are simple phenols encompassing hydroxycinnamic acid and its derivatives and hydroxybenzoic acids and its derivatives. Phenolic acids are powerful antioxidants and have been reported to have antibacterial, antiviral, anticarcinogenic, anti-inflammatory and vasodilatory actions [ 52 ].…”

“…Phenolic acids are powerful antioxidants and have been reported to have antibacterial, antiviral, anticarcinogenic, anti-inflammatory and vasodilatory actions [ 52 ]. Despite hydroxybenzoic acids having been found in carrots [ 52 ], the hydroxycinnamic acids are the main [ 11 ] or exclusive phenolic acids occurring in this vegetable [ 10 , 24 ].…”

“…Carrots are consumed either as processed (meals and juices) or fresh roots; specifically, the consumption of fresh-cut carrots is increasing due to changes in consumer behaviour [ 10 ]. Both processed and fresh carrots handling involves the production of wastes, including peel, which may represent a good source of important bioactive compounds.…”

“…However, removing the peels may result in changes in the nutritional/antioxidant properties of peeled products. In fresh and unstored carrots, a reduction in phenol compounds [ 10 , 11 , 12 ] as well as in carotenoid content [ 12 ] has been observed when peeled. Similarly, puree obtained from unpeeled carrots contained higher levels of phenols, carotenoids, and sugars compared with manually peeled roots [ 13 ].…”