Comparative Study of the Effect of Sample Pretreatment and Extraction on the Determination of Flavonoids from Lemon (Citrus limon)

Abstract

BackgroundFlavonoids have shown to exert multiple beneficial effects on human health, being also appreciated by both food and pharmaceutical industries. Citrus fruits are a key source of flavonoids, thus promoting studies to obtain them. Characteristics of these studies are the discrepancies among sample pretreatments and among extraction methods, and also the scant number of comparative studies developed so far.ObjectiveEvaluate the effect of both the sample pretreatment and the extraction method on the profile of flavonoids isolated from lemon.ResultsExtracts from fresh, lyophilized and air-dried samples obtained by shaking extraction (SE), ultrasound-assisted extraction (USAE), microwave-assisted extraction (MAE) and superheated liquid extraction (SHLE) were analyzed by LC–QTOF MS/MS, and 32 flavonoids were tentatively identified using MS/MS information. ANOVA applied to the data from fresh and dehydrated samples and from extraction by the different methods revealed that 26 and 32 flavonoids, respectively, were significant (p≤0.01). The pairwise comparison (Tukey HSD; p≤0.01) showed that lyophilized samples are more different from fresh samples than from air-dried samples; also, principal component analysis (PCA) showed a clear discrimination among sample pretreatment strategies and suggested that such differences are mainly created by the abundance of major flavonoids. On the other hand, pairwise comparison of extraction methods revealed that USAE and MAE provided quite similar extracts, being SHLE extracts different from the other two. In this case, PCA showed a clear discrimination among extraction methods, and their position in the scores plot suggests a lower abundance of flavonoids in the extracts from SHLE. In the two PCA the loadings plots revealed a trend to forming groups according to flavonoid aglycones.ConclusionsThe present study shows clear discrimination caused by both sample pretreatments and extraction methods. Under the studied conditions, liophilization provides extracts with higher amounts of flavonoids, and USAE is the best method for isolation of these compounds, followed by MAE and SE. On the contrary, the SHLE method was the less favorable to extract flavonoids from citrus owing to degradation.

Effect of vacuum‐drying, hot air‐drying and freeze‐drying on polyphenols and antioxidant capacity of lemon (Citrus limon) pomace aqueous extracts

“…Lemon pomace dried by freeze-drying had the highest neohesperidin content (64.23 lg mL À1 ) compared to those dried by hot air or under vacuum at different temperatures, indicating that neohesperidin loss occurs when lemon pomace is dried at high temperatures. These results are different to those reported by Ledesma-Escobar et al (2016a), who showed that rutin was higher in lemons dried by air compared to those dried by freeze-drying. Neohesperidin content of peels dried by hot air was significantly affected by temperature and dramatically decreased when the temperature increased from 90 to 110°C (from 31.04 to 21.55 lg mL À1 , respectively), whereas no significant reduction in neohesperidin content was observed in the peels dried under vacuum at different temperatures (no oxygen environment).…”

“…These results are in agreement with Lou et al (2014) who found that when air-drying temperature increased from 70 to 150°C, the TPC of immature calamondin (Citrus mitis Blanco) peels increased. On the other hand, Ledesma-Escobar et al (2016a) reported that lemons dried by freeze-drying had higher content of phenolic compounds compared to those dried by air-drying at 45°C. This difference could be attributed to the oxidation of some phenolic compounds in the samples dried at 45°C, because samples dried at low temperatures are exposed to oxygen for a long time (Wojdyło et al, 2014).…”

“…These results could be attributed to the liberation of some phenolic acids and flavonoids which are mainly found in bound form in plant matrix due to the heat (Hayat et al, 2010), as well as in the reduction in polyphenol oxidase (PPO) activity, which is an enzyme responsible for the selective oxidation of polyphenols, because high temperature tends to reduce PPO activity (Krapfenbauer et al, 2006). On the other hand, Ledesma-Escobar et al (2016a) reported that lemons dried by freeze-drying had higher content of phenolic compounds compared to those dried by air-drying at 45°C. On the other hand, Ledesma-Escobar et al (2016a) reported that lemons dried by freeze-drying had higher content of phenolic compounds compared to those dried by air-drying at 45°C.…”

“…The last decades witnessed an increased interest for the valorisation of phenolic compounds, such as flavonoids and phenolic acids by both pharmaceutical and food industries (Ledesma-Escobar et al, 2016a). Lemon (Citrus limon) peels being the main residue generated by lemon juice industry account for 50-65% of the whole fruit weight (Gonz alez- Molina et al, 2010) and are a good source of phenolic compounds, such as phenolic acids (ferulic, p-coumaric and sinapic acids) (Bocco et al, 1998) and flavonoids (flavanones, flavonols, flavones), which have been linked to antimicrobial (Dhanavade et al, 2011), anticancer (Wang et al, 2014) and antioxidant activities (Park et al, 2014).…”

Determination of cannabinoids in hemp nut products in Taiwan by HPLC‐MS/MS coupled with chemometric analysis: quality evaluation and a pilot human study

“…Principal component analysis (PCA) removes redundancy and noise while retaining meaningful information. [15] Using chemometrics, particular herbal preparations with complex components could be rapidly distinguished basing on either species, [16] geographic origins, [17] qualities, [18] pretreatments, [19] or toxicities. [20] The application of the analytical techniques with chemometric methods is a leading approach for shortening analysis and product development time.…”