The aim of the work was to explore the feasibility of using acorn flour as a novel and healthy ingredient in biscuits. The physico-chemical characteristics of acorn flour obtained from three different Quercus species were compared. Acorns of Quercus coccifera L. were the most antioxidant and were therefore used for preparing biscuits at two levels of addition, 30 and 60 g 100 g À1 on wheat flour basis. The physico-chemical and sensory characteristics of the obtained biscuits were then assessed. Acorn-added biscuits showed significantly (p < 0.05) higher content of phenolics, antioxidant activity and oxidative stability than control biscuits, prepared without acorn flour. These features improved as the level of acorn flour increased. As for appearance, the acorn-added biscuits were darker, larger, more voluminous and more friable than control biscuits. Higher levels of fermentative alcohols and esters, as well as Maillard reaction volatile compounds (particularly furans), were observed in the acorn-added biscuits.

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BACKGROUND Acorn fruit and its components and by‐products are receiving renewed interest due to their nutritional and phytochemical features. In particular, the oil extracted from acorns is recognized for having high nutritional quality and for being rich in bioactive compounds. Despite the growing interest, few papers are available that consider the evolution of acorn‐oil characteristics during storage. Our aim was to investigate the storage‐related changes in acorn oils extracted from three Quercus species grown in Algeria (Q. ilex, Q. suber, and Q. coccifera) 180 days after production, with a focus on polar and volatile compounds, not yet investigated. Basic quality parameters, phenolic content, antioxidant activity and induction time were also monitored. RESULTS The oxidation markers (peroxide value and UV absorptions) increased during storage, whereas antioxidants decreased. A distinctive volatile profile was observed at the time of production, which underwent changes during storage. Polar compounds increased, whereas induction time decreased. The oil extracted from Quercus suber L. was the most affected by storage time. CONCLUSION Floral and fruity volatile compounds detected in the oils’ headspace could explain the pleasant flavor of acorn oils reported by other authors. As with other vegetable oils, storage depletes both volatiles and antioxidants and produces oxidation compounds, such as oxidized triacylglycerols. However, the acorn oils that were studied were quite stable under storage in the dark at room temperature for 6 months. © 2020 Society of Chemical Industry

The current research involves the study of the effect of thermal treatment in boiling water (cooking) on the nutrient components and phytochemical contents of lentils. The changes of phenolic compounds and antioxidant activity of lentils before and after cooking; as well as the recovered water are investigated. Total polyphenol, flavonoid and tannin content were determined spectrophotometrically using standards methods and LC-MS/MS. Antioxidant activity of methanolic extracts was evaluated using DPPH (2,2-diphenyl-lpicrylhydrazyl) and ABTS (2,2’-azinobis-(3-ethyl benzo thiazoline-6-sulfonic acid)) assays. As compared to the raw lentils, cooking caused significant (p<0.05) decreases in total phenolic content (TPC), total flavonoid content (TFC), DPPH and ABTS free radicals scavenging activity. The obtained results indicated that the polyphenol content of cooking water was significantly higher than that of cooked and raw lentils; however the most important antioxidant activity was recorded for raw lentils. Several phenolic compounds were identified in fresh, cooked lentils and cooking water. The major compound for the three samples is tannic acid with a very remarkable value in the cooking water; while the minor compounds are naringenin for cooked lentils, apigenin for raw lentils and cooking water. Neoformed compounds have been also detected in the cooking water such as: quercetin, hespritin, tr-caffeic acid and chlorogenous acid in the cooking water.

Aim: The current study was undertaken to determine the total phenolic and flavonoid contents and to assess the antioxidant activity of two different extracts (flour and oil) of two Algerian Quercus species, Quercus ilex L. and Quercus suber L. Methods and Material: The oil extraction of the two species was achieved using the Soxhlet method. The obtained extracts were estimated for the chemical and physical constants (acidity, peroxide value, iodine value, and ultraviolet absorption indices). Total phenolic content was measured by spectrophotometry according to the Folin-Ciocalteu procedure and calculated as gallic acid equivalents (GAE). The studied extracts were submitted to an estimation of their flavonoid contents too, using aluminum chloride methods. Antioxidant ability was assessed by means of two distinct methods (DPPH• and ABTS•+). Results: The obtained results revealed that antioxidant properties, total phenolic, and total flavonoid contents differed significantly among selected species and extracts. The flour samples possessed the highest level of total phenolic contents (1101–1464 mg GAE/kg dry weight) and exhibited the highest antioxidant capacities with average values of 52.62–40.78 μmol TE g−1 dry weight and 36.19–44.50 μmol TE g−1 dry weight for DPPH and ABTS assays, respectively. Acorn oil extracts showed also remarkable antioxidant activity, up to 2.69 and 3.23 μmol TE g−1 oil (DPPH and ABTS test, respectively), even though the total phenolic contents were low (195.64–322.06 mg GAE /kg of oil). Total phenolic amounts were positively correlated with the antioxidant properties of Quercus flour and oil. Conclusions: Our study provides basic information on the presence of bioactive compounds and antioxidant capacity in acorn fruits, in order to consider their extracts as functional food ingredients and potential source of natural antioxidants. Keywords: Quercus ilex L., Quercus suber L., Total phenolic, Total flavonoid, Antioxidant activity.

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