Table 2.

Study and main findings of vegetable and fruit by-products utilization as functional ingredients in development of cookies and biscuits.

Product developed	Vegetable and fruit by-products	Study and main findings	References
Acha-based biscuits	Soybean hulls (SH)	In the study, 0, 2.5, 5.0, and 7.5% of soybean hulls flour (SH) was incorporated into acha-based biscuits. The incorporation of SH significantly affected the physical and functional properties of biscuits. It is found that an increment in SH level (0–7.5%) increased the water absorption (1.50–1.92 g/g) and the emulsifying capacities (50.27–53.41%), while decreased the bulk density (0.68–0.65 g/ml) and the oil absorption capacity (1.49–1.46 g/g). Besides, the incorporation of SH significantly increased the level of fiber (0.71 to 0.91%) and protein content (3.91 to 5.39%) while decreased the carbohydrate content (69.07 to 59.66 %) of the acha-based biscuit. In sensory evaluation, there was no significant difference in term of color, crispiness, aroma and general acceptability after the incorporation of SH. Nevertheless, 7.5% fortified biscuits had the highest acceptability in term of texture, which was significantly higher compared to the control. Nevertheless, the authors showed that 2.5% fortified biscuits were most preferred organoleptically.	(11)
Biscuits	Potato peels fiber (PF)	In the study, 0, 5, 10, and 15% of potato peel fiber (PF) was incorporated in biscuits. Preliminary analysis showed that the dried potato peel contained 76.40% dietary fiber and 14.04% protein. The incorporation of PF increased the carbohydrate, ash and fat content while reduced the protein content of biscuits. Based on the sensory evaluation, acceptability of biscuits decreased with the increasing PF content. The authors found that 5% formulation was preferable as more than 5% incorporation resulted in dark crumb color, hard texture which subsequently affected the appearance and mouthfeel.	(42)
Cookies	Grape pomace (GP)	In the study, 20 to 30% of grape pomace (GP) was incorporated in cookies formula. The fortification significantly affected the color and texture of cookies. It was found that the dietary fiber, total phenolic content (TPC) and free-radical scavenging activity of cookies increased with the increasing fortification of GP. The dietary fiber of fortified products ranged from 3.17 to 5.82 g/100 g and TPC of cookies increased from 23.98 mg GAE/100 g (20% GP) to 48.08 mg GAE/100 g (30% GP). Based on the sensory evaluation, the fortification of GP did not significantly affect the overall acceptability of cookie samples.	(55)
Cookies	Grape pomace (GP)	In this study, 5, 10, 15, and 20% of GP were incorporated in cookies. It was found that anthocyanin, total phenolic content (TPC), flavonoid, tannins and antioxidant activity of cookies significantly increased with increasing GP content. In addition, the color intensity was increased with the increasing GP amount and the maximum color intensity was found in cookies with 20% GP, where the fortification produced brown color in cookies. In term of sensory evaluation, 5% and 10% GP fortified cookies had significantly higher overall acceptability than control. Besides, 5% GP fortified cookies had the highest organoleptic score in all attributes. The study showed that 20% GP-fortified cookies with highest color intensity had the highest acceptability for color compared to others.	(56)
Cookies	Pomegranate peel (PGP)	Up to 7.5% of pomegranate peel (PGP) was incorporated in cookies and the dietary fiber increased from 0.32 to 1.96 g/100 g with addition of 7.5% PGP, which is more than 6 times higher than control. The supplementation of PGP significantly increased the minerals content, that is, calcium, sodium, potassium, iron, and zinc in cookies. It was found that the total phenolic compounds and antioxidant activity of cookies significantly increased with the increasing amount of PGP. Besides, the addition of PGP reduced the level of oxidative degradation where cookies with 7.5% PGP showed a lower free fatty acid (0.20%) after 4 months of storage, compared to control samples (0.22%) at the 2nd month of storage. Although the overall acceptability of cookies of PGP was lower than control, it remained acceptable under supplementation of 7.5%.	(76)
Biscuits	Pomegranate peel (PGP)	Up to 10% of pomegranate peel (PGP) was incorporated in the biscuits. It was found that PGP had considerable amount of dietary fiber, total polyphenol, β-carotene, calcium and iron. An increase of PGP incorporation significantly increased the hardness and decreased the cohesiveness and springiness of biscuits dough. The incorporation of PGP affected functional properties of biscuits where breaking strength was found to be increased, with a decreased spread ratio. Based on the sensory evaluation, biscuits with 7.5% PGP addition were well-accepted.	(77)
Cookies	Apricot kernel (AK)	In the study, up to 25% of apricot kernel (AK) were incorporated in the development of low-fat cookies as a fat replacer. The incorporation of AK significantly increased the total dietary fiber content of cookies and altered the color and texture of cookies. The hardness of cookies increased with increasing AK amount being incorporated, while the spread ratio was found to be decreased from 7.10 (0%) to 5.89 (25%). In the sensory evaluation, no significant difference was observed for overall sensory score at all concentrations of AK substitution.	(78)