Date of Defense
3-6-2025 1:00 PM
Location
F1-2119
Document Type
Thesis Defense
Degree Name
Master of Science in Food Science
College
CAVM
Department
Food Science
First Advisor
Dr. Sajid Maqsood
Keywords
Pomace, Green apple pomace, Beetroot pomace, polyphenols, Natural Deep Eutectic Solvents (NADES), Microwave-assisted extraction (MAE), Ultrasound-assisted extraction (UAE), Bread fortification.
Abstract
Pomace is a by-product from the juice processing industry that contains around 30-50% of the whole fruit or vegetable. The peel, pulp, seeds, and stem are still a rich source of nutrients, polyphenols, and bioactive compounds. This study was proposed to explore the potential of green apple pomace (GAP) and beetroot pomace (BP) for the extraction of polyphenolic compounds and fortification of bakery products. For a comprehensive characterization, the pomaces were processed into powders of three different particle sizes (≤250, 250-500, and ≥500 μm). The nutritional composition analysis concluded that GAP is a rich source of content (29.06 g/100 g), and BP is a good source of protein (11.45 g/100 g). The hydration properties and oil holding capacity (OHC) of BP outperformed the capacities of GAP. The color analysis showed that the lightness (L*) and yellowness (b*) values were higher for GAP, whereas the redness (b*) value was higher in BP, owing to its high betalain pigment content. Particle size distribution analysis of GAP across all particle sizes showed that it possesses a better proportion of finer particles than BP. The Fourier Transmission Infra-Red (FTIR) spectrum of GAP exhibited more evident peaks than BP. According to Differentia Scanning Calorimetry (DSC) analysis, BP formed less intense curves than GAP, indicating lower thermal activity. The Scanning Electron Microscopy (SEM) images of GAP exhibited a flaky and compact structure, while that of BP was fractured and loosely packed. The phenolic compounds were analyzed using homogenization-assisted water and acetone-based conventional extraction. Aqueous acetone extracts were more efficient in extracting polyphenols from GAP and BP, which also affected the polyphenol profiling, where many compounds could not be detected in the water extracts of both pomaces. The highest polyphenols recovered from GAP and BP were 7.16 and 1.56 mg GAE/g, respectively of particle sizes ≤250 μm. Further, the conditions for polyphenol extraction using Microwave Assisted-Extraction (MAE) and Ultrasound Assisted-Extraction (UAE)-coupled NADES were optimized. The extraction of polyphenols was carried out using lactic acid and fructose in the molar ratio of 2:1 and solid-to-solvent ratio of 1:40 at nine different time-power combinations for MAE and time-amplitude combinations for UAE. The highest Total phenolic content (TPC) was 14.48 mg GAE/ g and 19.27 mg GAE/ g in the NADES-MAE extracts of GAP and BP, respectively. While yield of UAE-NADES extraction was 30.92 mg GAE/g and 24.55 mg GAE/g TPC in GAP and BP, respectively. Ferric Reducing Antioxidant Power (FRAP) and 1,1-diphenyl-2-picrlthydrazyl (DPPH) values of MAE extracts of BP and GAP were the highest at 5 minutes and 0.8 kV, while that of UAE was at 6 minutes and 90% amplitude. The overall results suggested that MAE has better extraction efficiency for BP and GAP. Further, the pomaces and beetroot juice were utilized in the fortification of bread at varying concentrations (2.5%, 5%, 7.5%, and 10%). The nutritional composition resulted in the highest protein content of 8.39 g/100 g in the bread with only beetroot juice. The moisture content was more in GAP-enriched breads than in the control and BP-added breads. The color analysis showed a constant decline in the L* values in both pomaces added bread with an increase in the inclusion level. BP-added bread had the lowest L* values and the highest a* value was the highest in BP-added bread, but the b* values did not follow the general trend and varied across the samples. The specific volume of breads declined with an increase in pomace addition levels. Compared to control (2.49 cm3/g), bread with 10% GAP addition recorded the lowest volume (1.76 cm3/g). The texture analysis indicated that the hardness level increased with the pomace substitution, with the most hardness expressed by the highest pomace addition level of 7.5% and 10% in BP and GAP-added bread, respectively. TPC of bread significantly increased with the addition of pomaces when compared to control. GAP-added bread recorded the highest TPC of 3.33 mg GAE/g with a 10% addition. TPC of BP and juice-added breads were higher than those with only BP added and the highest value was 2.78 mg GAE/g with 7.5% addition. The FRAP and DPPH also followed the same trend as TPC, with the values increasing with the pomace addition level. In-vitro digestion of breads suggested that TPC was significantly affected by the digestion process. The values declined overall pomace levels in BP and GAP bread with much difference compared to un-digested samples, pointing out the incompatibility of polyphenols during digestive processes. This research concluded the potential of BP and GAP as a rich source of bioactive compounds when extracted using highly competent techniques. It can also be utilized as a sustainable fortification ingredient in foods. This study demonstrates the role of food-based research in reducing food waste, enhancing food product value, and contributing to circular economy practices within the food industry.
EXPLORING THE FUNCTIONAL POTENTIAL OF BEETROOT AND GREEN APPLE POMACE: CHARACTERIZATION, POLYPHENOLIC EXTRACTION AND APPLICATION IN THE BAKERY PRODUCT
F1-2119
Pomace is a by-product from the juice processing industry that contains around 30-50% of the whole fruit or vegetable. The peel, pulp, seeds, and stem are still a rich source of nutrients, polyphenols, and bioactive compounds. This study was proposed to explore the potential of green apple pomace (GAP) and beetroot pomace (BP) for the extraction of polyphenolic compounds and fortification of bakery products. For a comprehensive characterization, the pomaces were processed into powders of three different particle sizes (≤250, 250-500, and ≥500 μm). The nutritional composition analysis concluded that GAP is a rich source of content (29.06 g/100 g), and BP is a good source of protein (11.45 g/100 g). The hydration properties and oil holding capacity (OHC) of BP outperformed the capacities of GAP. The color analysis showed that the lightness (L*) and yellowness (b*) values were higher for GAP, whereas the redness (b*) value was higher in BP, owing to its high betalain pigment content. Particle size distribution analysis of GAP across all particle sizes showed that it possesses a better proportion of finer particles than BP. The Fourier Transmission Infra-Red (FTIR) spectrum of GAP exhibited more evident peaks than BP. According to Differentia Scanning Calorimetry (DSC) analysis, BP formed less intense curves than GAP, indicating lower thermal activity. The Scanning Electron Microscopy (SEM) images of GAP exhibited a flaky and compact structure, while that of BP was fractured and loosely packed. The phenolic compounds were analyzed using homogenization-assisted water and acetone-based conventional extraction. Aqueous acetone extracts were more efficient in extracting polyphenols from GAP and BP, which also affected the polyphenol profiling, where many compounds could not be detected in the water extracts of both pomaces. The highest polyphenols recovered from GAP and BP were 7.16 and 1.56 mg GAE/g, respectively of particle sizes ≤250 μm. Further, the conditions for polyphenol extraction using Microwave Assisted-Extraction (MAE) and Ultrasound Assisted-Extraction (UAE)-coupled NADES were optimized. The extraction of polyphenols was carried out using lactic acid and fructose in the molar ratio of 2:1 and solid-to-solvent ratio of 1:40 at nine different time-power combinations for MAE and time-amplitude combinations for UAE. The highest Total phenolic content (TPC) was 14.48 mg GAE/ g and 19.27 mg GAE/ g in the NADES-MAE extracts of GAP and BP, respectively. While yield of UAE-NADES extraction was 30.92 mg GAE/g and 24.55 mg GAE/g TPC in GAP and BP, respectively. Ferric Reducing Antioxidant Power (FRAP) and 1,1-diphenyl-2-picrlthydrazyl (DPPH) values of MAE extracts of BP and GAP were the highest at 5 minutes and 0.8 kV, while that of UAE was at 6 minutes and 90% amplitude. The overall results suggested that MAE has better extraction efficiency for BP and GAP. Further, the pomaces and beetroot juice were utilized in the fortification of bread at varying concentrations (2.5%, 5%, 7.5%, and 10%). The nutritional composition resulted in the highest protein content of 8.39 g/100 g in the bread with only beetroot juice. The moisture content was more in GAP-enriched breads than in the control and BP-added breads. The color analysis showed a constant decline in the L* values in both pomaces added bread with an increase in the inclusion level. BP-added bread had the lowest L* values and the highest a* value was the highest in BP-added bread, but the b* values did not follow the general trend and varied across the samples. The specific volume of breads declined with an increase in pomace addition levels. Compared to control (2.49 cm3/g), bread with 10% GAP addition recorded the lowest volume (1.76 cm3/g). The texture analysis indicated that the hardness level increased with the pomace substitution, with the most hardness expressed by the highest pomace addition level of 7.5% and 10% in BP and GAP-added bread, respectively. TPC of bread significantly increased with the addition of pomaces when compared to control. GAP-added bread recorded the highest TPC of 3.33 mg GAE/g with a 10% addition. TPC of BP and juice-added breads were higher than those with only BP added and the highest value was 2.78 mg GAE/g with 7.5% addition. The FRAP and DPPH also followed the same trend as TPC, with the values increasing with the pomace addition level. In-vitro digestion of breads suggested that TPC was significantly affected by the digestion process. The values declined overall pomace levels in BP and GAP bread with much difference compared to un-digested samples, pointing out the incompatibility of polyphenols during digestive processes. This research concluded the potential of BP and GAP as a rich source of bioactive compounds when extracted using highly competent techniques. It can also be utilized as a sustainable fortification ingredient in foods. This study demonstrates the role of food-based research in reducing food waste, enhancing food product value, and contributing to circular economy practices within the food industry.