Investigation of the Coffea Arabica substitution with roasted date seed on Physicochemical and sensory properties of coffee brew

Abstract

Introduction: Date seeds (also known as pits and kernel) are among the most important wastes which are generated during direct consumption or from the date processing industries. Despite the presence of several nutrients and bioactive compounds and their subsequent beneficial health effects, these by-products are frequently discarded to use as soil fertilizer or as feed for livestock. Roasting opens a cost effective way to include date seed in the human diet. The aqueous extract of roasted date seed represented a coffee-like beverage. Date seed coffee has a relatively low acceptance among consumers and is usually supplemented with a variety of additives to improve the taste. Therefore, due to rising the global coffee price, in the present study, we aimed to substitute Arabica beans with roasted date seeds in order to make a coffee beverage similar to Coffea Arabica boiled coffee brew.Materials and Methods: Coffea Arabica and roasted date seeds were obtained from local markets and 10 grams of powder (100% Arabica coffee (A100), 100% date kernels (D100) or a mixture of Arabica coffee powder and date seeds in proportions of 10 (D10), 35 (D35), 50% (D50) of date seed) was brewed using 100 ml of boiling distilled water. The brewed coffees were examined in terms of lipid, protein, caffeine, acrylamide, total phenol and total flavonoids content. Other parameters including color, viscosity, pH, DPPH and FRAP assays followed by sensorial evaluation were evaluated, as well.Results and Discussion: Substitution with roasted date seed resulted in lower lipids, protein and caffeine of coffee brews as the values were decreased from 330.67, 956.75, 76.51 mg/100 mL in Coffea Arabica (100%) to 192.61, 149.00, 45.59 mg/100 in date seed coffee (100%), respectively. Higher amounts of date seed also resulted in lower pH and acrylamide content. Accordingly, pH was decreased from 5.7 in D100 to 4.4 in A100. Acrylamide content was attenuated from 5.06 µg/100 mL in A100 to 1.71 µg/100 mL in D100. Reduction in viscosity was also observed from 0.93 (A100) to 0.86 mPa.s (D100). The mean value of the color parameter including L*, a* and b* in the 100% Coffea Arabica brew was more than the 100% date seed coffee, which indicated that the coffees brewed from date seeds in different proportions were brighter and had higher red and yellow color parameters. Substitution with date seed had less effect on the total phenol content as TPC of coffees ranged from 28 to 42 mg/100 mL for 100% date seeds brew and Coffea Arabica brew, respectively. On the other hand, the flavonoid content (TFC) of coffees was significantly affected by the amount of date seeds (5 to75 mg/100 mL for 100% date seeds and Coffea Arabica brew, respectively). All brews have high antioxidant activity. For DPPH the highest results (88/9 %) were obtained in the coffee brewed from 100% date seeds, while the FRAP value it was vice versa. The results of sensory evaluation indicated a high similarity among A100 and D10 coffees as parameters such as aroma, color and texture (concentration) of coffee were evaluated appropriate. The results also showed that substituting Coffea Arabica up to 35% with roasted date seeds can improve the overall acceptance of the coffee brews by reducing bitterness.Conclusion: In general, the ability to replace Coffea Arabica with date seeds up to 10 and 35% was reported acceptable in terms of sensory characteristics, as the color and aroma were similar to 100% Coffea Arabica. Besides that due to reduced bitterness, the overall acceptance were almost high.