Abstract
INTRODUCTION: Almond production has increased worldwide due to its nutritional relevance. Consequently, high amounts of almond by-products are generated, which are currently used as energy source or discarded. Nowadays, there is a growing interest in finding natural ingredients to replace synthetic ones. The valorization of food by-products is, thus, of great importance to develop innovative and sustainable applications. This is the case of almond shells (AS), a by-product with bioactive compounds that can be used as innovative ingredients.
OBJECTIVES: This work aimed to develop and optimize a sustainable extraction process to recover the phenolic compounds of AS.
METHODOLOGY: AS (Prunus dulcis (Mill.) D. A. Webb) from Trás-os-Montes (Portugal) were used for this study. The extraction conditions tested were mass/volume ratio, temperature (room temperature (RT), 40, 60, 80, 95 °C), and
time by stirring (1h/2h) and maceration (12h/24h). Total phenolic and flavonoid contents were determined by spectrophotometric methods. Antioxidant activity was evaluated by FRAP and DPPH• inhibition assays. A tentative identification of phenolic compounds was carried out by HPLC.
RESULTS: Total phenolics extraction increased until 95 °C (438 mg GAE/L). In turn, total flavonoids increased until 85 °C (24 mg CE/L). Concerning the antioxidant activity evaluated by the FRAP assay, there were no significant differences between RT and 40 °C (p>0.05), but then the FRAP values increase with temperature. Regarding the DPPH• inhibition assay, no statistical differences (p>0.05) were observed between extractions performed at 80 and 95 °C.
CONCLUSIONS: Results showed that the highest amounts of antioxidant compounds were obtained with maceration of 5 g of AS, during 24h at 80 ºC. It is foreseen that the AS extracts may have potential application in food industry, since the major compound of the aqueous extract was vanillin (used as a flavouring compound in food and beverage products and as a natural preservative).
OBJECTIVES: This work aimed to develop and optimize a sustainable extraction process to recover the phenolic compounds of AS.
METHODOLOGY: AS (Prunus dulcis (Mill.) D. A. Webb) from Trás-os-Montes (Portugal) were used for this study. The extraction conditions tested were mass/volume ratio, temperature (room temperature (RT), 40, 60, 80, 95 °C), and
time by stirring (1h/2h) and maceration (12h/24h). Total phenolic and flavonoid contents were determined by spectrophotometric methods. Antioxidant activity was evaluated by FRAP and DPPH• inhibition assays. A tentative identification of phenolic compounds was carried out by HPLC.
RESULTS: Total phenolics extraction increased until 95 °C (438 mg GAE/L). In turn, total flavonoids increased until 85 °C (24 mg CE/L). Concerning the antioxidant activity evaluated by the FRAP assay, there were no significant differences between RT and 40 °C (p>0.05), but then the FRAP values increase with temperature. Regarding the DPPH• inhibition assay, no statistical differences (p>0.05) were observed between extractions performed at 80 and 95 °C.
CONCLUSIONS: Results showed that the highest amounts of antioxidant compounds were obtained with maceration of 5 g of AS, during 24h at 80 ºC. It is foreseen that the AS extracts may have potential application in food industry, since the major compound of the aqueous extract was vanillin (used as a flavouring compound in food and beverage products and as a natural preservative).
| Original language | English |
|---|---|
| Pages | 43-43 |
| Number of pages | 1 |
| DOIs | |
| Publication status | Published - 11 May 2018 |
| Event | XVII Congress of Food and Nutrition - Lisbon, Portugal Duration: 10 May 2018 → 11 May 2018 |
Conference
| Conference | XVII Congress of Food and Nutrition |
|---|---|
| Country/Territory | Portugal |
| City | Lisbon |
| Period | 10/05/18 → 11/05/18 |
Keywords
- almonds
- antioxidants
- food by-products