Changes in composition of phenolic compounds and tocopherols in broccoli heads during short-term storage

Abstract

S u m m a r yBroccoli (Brassica oleracea L. var. italica) contains numerous biologically active compounds. However, their levels change during processing and storage.The objective of the research study was to determine the effect of short-term storage (1 ÷ 4 days) of broccoli heads at different temperatures (3 ºC, 16 ºC, and 21 ºC) on the contents of phenolic acids, selected flavonoids (quercetin and kaempferol), and tocopherols. Broccoli heads were harvested in autumn when they reached their maximum size and their buds were 2 mm in diameter.The content of phenolics and tocopherols depended on the storage time of broccoli heads. The lowest content of phenolics was found immediately after the broccoli was harvested, whereas the highest content thereof was reported after 4 days of storage. However, the storage temperature did not impact the contents of those compounds. In the research study, the content of caffeic acid was reported to be highest in the fresh broccoli heads; the content of sinapic acid was the second-highest, and that of the ferulic acid was the third-highest. The content of kaempferol in the broccoli heads was higher than that of quercetin. No differences were reported in the content of quercetin and kaempferol at particular storage temperatures on every single day of the experiment. An increase was reported only when compared with the control sample (the 0 day of storage). In the broccoli heads, the predominant tocopherol was α-tocopherol. The lowest loss in the total tocopherols occurred while storing at a temperature of 3 ºC and the highest: at a temperature of 21 ºC.Key words: Brassica oleracea L. var. italica, HPLC, phenolics, tocopherols, storage, temperature Dr A. Kałużewicz, dr J. Lisiecka, dr W. Krzesiński, dr T. Spiżewski, dr B. Frąszczak, Katedra Warzywnictwa, Wydz. Ogrodnictwa i Architektury, Uniwersytet Przyrodniczy w Poznaniu, ul. Dąbrowskiego 159, dr M. Gąsecka, dr hab. A. Waśkiewicz, Katedra Chemii, Wydz. Technologii Drewna, Uniwersytet Przyrodniczy w Poznaniu, ul. Wojska Polskiego 25, 128Alina Kałużewicz i wsp. IntroductionBroccoli (Brassica oleracea L. var. italica) is a vegetable of high nutritional value owing to the abundance of health-promoting phytochemicals therein [1]. The variation among the contents of bioactive components therein depends both on the genetics and the environment including the conditions of growing it and the pre-harvest and/or postharvest conditions [25]. Of all the bioactive compounds, phenolics deserve special attention [1] because of their role in preventing cancer and cardiovascular diseases [3]. Owing to their health-promoting effects, the phenolic compounds were intensively investigated over recent years [29]. Depending on their structure, phenolic compounds may be classified into simple phenols, phenolic acids, hydroxycinnamic acid derivatives, and flavonoids [10].Phenolic compounds, especially flavonoids, are among the major antioxidants in Brassica vegetables [24]. Many research studies show that broccoli has a very high content of total pheno...

Influence of biostimulants on phenolic content in broccoli heads directly after harvest and after storage

“…In the present study, the concentration of kaempferol in broccoli heads was 3-4 times higher than that of quercetin. This is consistent with the results of the research conducted by Gliszczyńska-Świgło et al (2007), Kałużewicz et al (2016) and Koh et al (2009). In contrast, Bahorun et al (2004) observed that the concentration of quercetin was 5 times higher than that of kaempferol.…”

The influence of biostimulants on the content of phenolic compounds in broccoli heads during short-term storage at room temperature

“…The total phenolic content and the amounts of ferulic, sinapic and caffeic acids increased along with the duration of storage both in the plants treated with the biostimulants and in the control plants. This is consistent with the results of our previous studies (Kałużewicz et al, 2016), where the total phenolic content increased by more than 180% after three days of storage, whereas the content of caffeic, ferulic and sinapic acids grew by 60%, 198% and 151%, respectively. Leja et al (2001) and Starzyńska et al (2003) observed the same trend in broccoli heads stored at room temperature.…”

“…However, this trend was not observed in the first year of the experiment, when the content of quercetin after three days of storage was the same as in the fresh heads, while the content of kaempferol decreased. The increase in the contents of quercetin and kempferol during storage in the second year is consistent with the results of another study by Kałużewicz et al (2016). The researchers observed that after three days of storage at a temperature of 21°C the amount of quercetin increased by 56%, while the content of kempferol grew by 27%.…”

Impact of Different Packaging Systems on Selected Antioxidant Properties of Frozen-Stored Broccoli

“…In this study the decrease in total polyphenols was continuing by the second month of research; next the level of these constituents increased substantially to be continued at high level, near the level in the blanched material, until the end of a study period. An increase in the level of these constituents to the value even exceeding the initial value has also been confirmed by Kaluzewicz et al [49] and Kim et al [50]; however, an increase noted in this research did not exceeded the level determined in the fresh vegetable. As Hakkinen and Torronen [51] claim, throughout several months of storage of strawberries, both an increase and a decrease in total polyphenols were possible.…”