Affiliation:
1. Laboratory of Food Chemistry and Technology, School of Chemical Engineering, National Technical University of Athens, Zografos Campus, 9 Iroon Polytechneiou Street, 15772 Athens, Greece
Abstract
Spent Coffee Ground (SCG) is the main coffee industry by-product, rich in dietary fibers and polyphenols. The extractable material of SCG was fractionated, and the phenolic compounds were identified and quantified. Chlorogenic and neochlorogenic acids were identified as the main phenolic components, and the Total Phenolic Content (TPC) of SCG was determined to be 2.16% (dry SCG basis). Furthermore, SCG was characterized in terms of Total Dietary Fiber content, which amounted to 66%. The SCG was valorized for the development of a bakery product (cookie) enhanced with fiber and bioactive polyphenols. Cookies were produced with the addition of 4% and 7% dry and defatted SCG (baked cookie basis). The produced cookie prototypes presented TPC and dietary fiber dependent on the addition level of SCG. TPC values were determined at 588 and 1017 ppm, while dietary fiber values were at 2.7 and 4.6%, respectively. The shelf life of the cookies was monitored over 143 days at three different temperatures (25 °C, 35 °C, and 45 °C) in terms of texture (hardness), color, Peroxide Value (PV), and TPC. It was observed that the PV value significantly increased in samples with incorporated SCG, stored at 45 °C, while in those stored at 25 °C and 35 °C, PV remained at low levels. The TPC of the SCG-enriched samples remained practically constant during the shelf life analysis, while color and hardness increased (mathematically modeled). SCG-added cookies were characterized by increased darkness, increased hardness, and a mild (desirable) coffee flavor. The overall sensory impression scores for 0%, 4%, and 7% SCG-added cookies were 7.5, 8.0, and 8.2, respectively. Based on sensory evaluation test results, the shelf lives of 0%, 4%, and 7% SCG at 25 °C were 359, 435, and 471 days, respectively. Overall, SCG is a potentially valuable ingredient that can be used to develop innovative food (baked) products with enhanced nutritional value and increased shelf life.