About

Gabriel Harris is a Professor and Co-Director of Undergraduate Programs for Food Science at North Carolina State University, located in the Schaub Food Science Building. His primary research interest is understanding how food processing affects the health properties of food. Specifically, he examines the anti-inflammatory effects of plant foods, such as tea, chocolate, and muscadine grapes, and their effects on blood sugar regulation and satiety. Harris enjoys teaching courses in both face-to-face and distance education formats, including Food Science and the Consumer, Analytical Techniques in Food and Bioprocessing Sciences, and Nutraceuticals and Functional Foods. He holds a Ph.D. in Food Science and Nutrition from The Ohio State University, an M.S.. in Food Science with a Statistics Minor from North Carolina State University, and a B.S. in Home Economics with a Dietetics Concentration from Morgan State University.

Research topics

• Medicine
• Internal medicine
• Psychology
• Anesthesia
• Chromatography
• Physical therapy
• Physical medicine and rehabilitation
• Chemistry
• Neuroscience
• Dentistry
• Food science
• Anatomy

Selected publications

• Coffee Roast Level, Timing, and Carbohydrate Source Affect Peak Blood Glucose and Area Under the Curve Values in a Randomized Pilot Clinical Trial

  Journal of Nutrition and Metabolism · 2025-01-01

  articleOpen accessSenior author

  Roasted coffee’s bioactive compounds may affect human glucose metabolism. This pilot clinical trial investigated the impact of coffee roast level, coffee timing, and carbohydrate (CHO) type on blood glucose responses. Healthy participants (15 female and 4 male) completed this six‐week, randomized, single‐blinded study. Treatments comprised combinations of roast levels (light, medium, or dark), coffee timings (pre‐, co‐, or post‐CHO ingestion), and CHO types: oral glucose tolerance test (OGTT) beverages or a standardized breakfast designated as PreO, PreB, CoO, CoB, PostO, and PostB. Subjects consumed 300 mL of test beverages and provided 10 capillary blood samples over 4 h. Coffees were analyzed for caffeine, 3, 4, and 5 chlorogenic acids (CGA), trigonelline, total phenols, color, °Brix, and total dissolved solids (TDS). Significant ( p < 0.05) differences in 3CQA, 5CQA, and trigonelline, but not caffeine and 4CQA, were observed across roast levels. Prior to CHO, coffee did not increase blood glucose, but potentiated increases after CHO. PreO and PreB treatments produced the highest peak glucose values (160 mg/dL). This was not observed for co‐ or posttreatments. In the CoO combination, AUC values were significantly ( p < 0.05) lower than placebo only for medium roast. In posttreatments, peak glucose levels were higher following OGTT than breakfast, but AUCs did not differ. Light roast coffee yielded the lowest AUC for PreO and the highest peak at 3 h in the CoO combination. Medium roast resulted in the lowest AUC across all time points in CoO, while both medium and dark roasts elevated AUC in PreO. Only dark roast increased AUC in the PreB condition. Three AUC main effects (CHO type, coffee roast, and timing) and two interactions (timing × roast; timing × CHO × roast) were highly significant ( p < 0.002). These findings may benefit those desiring temporary blood glucose elevations for exercise performance and recovery versus those seeking to moderate glucose. Trial Registration: ClinicalTrials.gov identifier: NCT05119153

  PublisherDOI

• Impact Of Caffeine Supplementation On Anaerobic Exercise Performance

  Medicine & Science in Sports & Exercise · 2025-09-16

  article

  Caffeine has been shown to be an effective ergogenic aid in aerobic exercise, but the literature on whether it is effective during anaerobic exercise is unclear. PURPOSE: The purpose of this investigation is to examine the impact of different levels of caffeine on anaerobic exercise performance. METHODS: Twelve participants (7 male, 5 female; age = 25.0 ± 1.3 years; weight = 78.6 ± 3.6 kg; height = 1.72 ± 3.54 m) completed four experimental sessions. During the first session, participants were familiarized with all procedures used in the experimental sessions. During the three experimental sessions, subjects completed the following assessments of anaerobic performance: countermovement jump (CMJ), leg press, and shoulder flexion dynamometry. Prior to each experimental session, subjects consumed a 12-oz coffee beverage with decaffeinated coffee (PLAC), 220 mg (MID), or 450 mg (HIGH) of caffeine. Treatments were blinded to participants and applied in a randomized order. Subjects completed experimental sessions after a 4-hour food and 12-hour caffeine fast. RESULTS: Dynamic strength index during CMJ was greater during the HIGH (3.07 ± 0.32 cm.sec-1) condition compared to PLAC (2.56 ± 0.23 cm.sec-1) and MID (2.90 ± 0.31 cm.sec-1) (p = 0.01). Force generated during the shoulder press was greater during HIGH (87.9 ± 6.8 N) than in PLAC (77.2 ± 5.8 N) and MID (77.6 ± 6.0 N) (p = 0.03). Maximal force generated during the leg press was higher during HIGH (1813 ± 210 N) than in PLAC (1501 ± 144 N) (p = 0.02). CONCLUSION: These findings indicate that the level of caffeine consumption can impact anaerobic exercise performance.

  PublisherDOI

• Coffee Roast Level and Anaerobic Exercise

  Current Developments in Nutrition · 2025-05-01

  articleOpen access
  PublisherOA PDFDOI

• Impact Of Caffeine Supplementation On Aerobic Performance And Muscle Strength

  Medicine & Science in Sports & Exercise · 2025-09-16

  articleSenior author

  Caffeine has been proven to be an effective ergogenic aid in aerobic exercise, but it is unclear if caffeine can simultaneously improve aerobic and strength performance. PURPOSE: The purpose of this investigation is to examine the impact of different levels of caffeine on aerobic performance and muscle strength. METHODS: Twelve participants (7 male, 5 female; age = 25.0 ± 1.3 years; weight = 78.6 ± 3.6 kg; height = 1.72 ± 3.54 m) completed four experimental sessions. During the first session, participants were familiarized with all procedures used in the experimental sessions. During the three experimental sessions, subjects completed the hand grip test and a 5-km time trial. Hand grip strength was assessed using the Jamar Plus Digital Hand Dynamometer. The 5-km time trial was completed on a Lode Corival CPET cycle ergometer. Prior to each experimental session, subjects consumed a 12-oz coffee beverage with decaffeinated coffee (PLAC), 220 mg (MID), or 450 mg (HIGH) of caffeine. Treatments were blinded to participants and applied in a randomized order. Subjects completed experimental sessions after a 4-hour food and 12-hour caffeine fast. RESULTS: Hand grip strength was greater during the HIGH (44.5 ± 3.6 kg) condition compared to PLAC (41.8 ± 3.2 kg) and MID (42.7 ± 3.2 kg) (p = 0.01). Subjects completed the 5-km time trial more quickly during the HIGH (6.1 ± 0.5 min) condition compared to PLAC (7.8 ± 1.0 min) (p = 0.03) and MID (7.5 ± 0.8 min) (p = 0.04). CONCLUSION: These findings indicate that the level of caffeine consumption can simultaneously impact anaerobic exercise performance and muscle strength.

  PublisherDOI

• Identifying differential effects from eleven mixing techniques on mRNA lipid nanoparticle physicochemistry and biological performance

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-11-09

  preprintOpen access

  Abstract Lipid nanoparticle (LNP) formulation requires a mixing step. Many studies, especially from academic groups, utilize either microfluidic mixers or hand mixing to prepare LNPs, but commercial-scale processes use turbulent-flow mixers. This discrepancy in mixing techniques has been underexplored, as LNPs made by different techniques may exhibit different performance, such that bench-scale results cannot be replicated using materials manufactured at scale. We here isolate and interrogate the effect of primary mixing. Lipid nanoparticles are produced from ten mixers (one used in two ways), holding all other formulation parameters constant, to directly compare across techniques. LNPs produced from the different mixers exhibit widely different physical properties and biological performance. Notably, manual pipetting common in academic practice yields particles that do not resemble those produces by turbulent-flow mixers. Findings are connected mechanistically to physicochemical characteristics that arise from the different flow regimes. Further establishing the relationship between mixing and LNP properties is critical. Graphical abstract

  PublisherOA PDFDOI

• Effect Of Coffee Supplement On Anaerobic Exercise Performance

  Medicine & Science in Sports & Exercise · 2024-09-16

  articleSenior author

  Coffee has been proven to be an effective ergogenic aid in aerobic exercise, but the literature on whether it is effective during anaerobic exercise is lacking. The impact of coffee supplementation on exercise performance is mediated by caffeine. The caffeine content of the two intervention beverages were 100mg and 400mg, as to not exceed the daily recommended dose of 400 mg. PURPOSE: The purpose of this investigation is to examine the impact of different levels of caffeine on anaerobic exercise performance. METHODS: Six participants (3 male, 3 female; age=23.7±0.2 years; weight=81.0±3.6 kg; height=1.75±0.03 m) completed four experimental sessions. During the first session, participants were familiarized to all procedures used in the experimental sessions. During the three experimental sessions, subjects completed the following assessments of anaerobic performance: countermovement jump (CMJ), plyometric push-up, leg press, shoulder flexion dynamometry, and hand grip dynamometry. Prior to each experimental session, subjects consumed a 16-oz coffee beverage with 0 mg (PLAC), 100 mg (MID), or 400 mg (HIGH) of caffeine. Treatments were blinded to participants and applied in a randomized order. Subjects completed experimental sessions after a 4-hour food and 12-hour caffeine fast. RESULTS: Dynamic strength index during CMJ was greater during the PLAC (3.62±0.48 cm.sec-1) and HIGH (3.49±0.51 cm.sec-1) conditions compared to MID (2.98±0.23 cm.sec-1) (p=.04). Force generated during the shoulder press was greater during HIGH (68.5±7.3 N) than in PLAC (64.5±8.0 N) (p=.0061). No differences were observed in hand grip or leg press performance. CONCLUSION: These findings indicate that the level of caffeine consumption can impact anaerobic exercise performance.

  PublisherDOI

• Ash Analysis

  Food science text series · 2024-01-01 · 3 citations

  book-chapter1st authorCorresponding
  PublisherDOI

• Effects Of Green, Light, Medium, And Dark Roast Coffees On Grip Strength And Jump Height

  Medicine & Science in Sports & Exercise · 2023-09-01

  article

  Coffee has been reported to improve aerobic exercise performance, but its effects on anaerobic performance are not well studied. Roasting affects coffee chemistry, both destroying and creating compounds that impact flavor and may also affect exercise performance. PURPOSE: This double-blind crossover study investigated the impact of coffee roast level on grip strength and countermovement jump (CMJ) height in human test subjects. METHODS: Baseline performance was assessed in ten subjects using a digital hand dynamometer for grip strength and a force plate for CMJ. Subjects then repeated each test on five separate days after green coffee, light, medium, and dark roast coffee (brewed at 55 g ground coffee per liter of water), and water control treatments were consumed thirty minutes before each trial. RESULTS: Coffee samples were tested for caffeine and chlorogenic acid (3CQA) content. Caffeine results were: green 68.54 ± 0.15 mg, light 91.58 ± 0.26 mg, medium 87.96 ± 0.40 mg, dark roast 78.90 ± 0.27 mg. 3CQA results were: green 114.70 ± 1.40 mg, light 113.65 ± 0.05 mg, medium 81.18 ± 0.65 mg, dark roast 19.31 ± 0.05 mg. Grip strength results were: baseline 42.81 ± 12.24 kg, control 43.06 ± 11.14 kg, green coffee 43.39 ± 10.61 kg, light roast 43.13 ± 10.46 kg, medium roast 43.11 ± 10.32 kg, and dark roast 44.25 ± 12.00 kg. CMJ height results were: baseline 20.73 ± 8.12 cm, control 22.33 ± 8.71 cm, green coffee 18.60 ± 8.51 cm, light roast 21.84 ± 10.20 cm, medium roast 21.98 ± 9.85 cm, and dark roast 19.20 ± 7.80 cm. While average grip strength values were numerically higher in coffee-treated subjects than for baseline, a one-way ANOVA determined there were no significant (p < 0.05) differences among treatment groups for grip strength or CMJ height. CONCLUSIONS: This study did not yield enough evidence to corroborate coffee consumption or roast level having a significant impacts on anaerobic performance. Future studies should include more participants and more measures to determine if preexercise coffee intake impacts anaerobic performance.

  PublisherDOI

• Impact Of Coffee Roast Level On Force Production During The Counter Movement Jump

  Medicine & Science in Sports & Exercise · 2023-09-01

  article

  Coffee has been shown to improve aerobic exercise performance. The impact of coffee on activities that require muscular power, like jumping, is unclear. Roasting affects coffee chemistry, both destroying and creating compounds that impact flavor and may also affect exercise performance. PURPOSE: To investigate if coffee roast level impacts force-related parameters during counter movement jump in healthy young adults. METHODS: Ten healthy young adults performed three trials of counter movement jumps on force platforms. Data were collected at 1000 Hz. Subjects repeated the tests on five separate days after consumption of green, light, medium, and dark roast coffees (brewed at 55 g ground coffee per liter of water), as well as a no coffee control. All treatments were consumed thirty minutes before each trial. Treatments were applied in a randomized counterbalanced fashion. Data were processed to extract ground-reaction force variables in each of the five phases of the counter-movement jump: unweighing phase, eccentric phase, concentric phase, flight phase and landing phase. Mean and coefficient of variation of force-parameters were analyzed using 1-way ANOVA. RESULTS: No significant differences were found. Relative impulse during eccentric phase were light roast: 3.1 (.76), medium roast: 3.26 (1.05), dark roast: 3.44 (1.11), green coffee: 3.09 (0.66), and control: 3.19 (3.68). Relative impulse during concentric phase were light roast: 5.77 (.43), medium roast: 5.59 (0.80), dark roast: 5.37 (1.16), green coffee: 5.66 (0.51), and control: 5.55 (0.52). Peak power were light roast: 2272.87 (1269.02), medium roast: 2312.70 (1163.80), dark roast: 2016.76 (1043.65), green coffee: 1980.52 (999.03), and control: 2204.75 (1135.99). Modified reactive strength were light roast: 2.27 (.65), medium roast: 2.14 (0.68), dark roast: 2.14 (.50), green coffee: 2.32 (0.49), and control: 2.23 (0.52). CONCLUSIONS: Coffee roast level did not impact force related parameters during the counter movement jump. The procedures used in this investigation may not have been effective at manipulating the bioactive compounds within the body that are theorized to improve physical performance. Future investigations should document changes in these bioactive compounds to confirm that coffee roast level does not impact muscular power.

  PublisherDOI

• The Effects Of Quinine On Performance And Brain Activity During 5 Time Sit To Stand

  Medicine & Science in Sports & Exercise · 2022 · 1 citations

  • Psychology
  • Medicine
  • Anesthesia

  Bitter-tasting oral stimulants can produce an ergogenic effect during power activities in younger, athletic populations. It has been proposed that this response may be mediated by enhanced excitability of the motor cortex by stimulation of taste receptors in the mouth. PURPOSE: To determine the effects of a bitter-tasting quinine solution on performance and brain activity during the 5 time sit to stand test (5TSTS). METHODS: 10 healthy young adults (10 female) (Age 22-31 years) were provided 4 bitter quinine solutions immediately prior (20 s) to 5TSTS. Brain activity was monitored during each trial using a 128-channel EGI Geodesic EEG system 400. 5TSTS time and trunk lean angle were measured using wearable sensors. The four solutions provided were placebo (PLAC), 80 ppm quinine (Qlow). 320 ppm quinine (Qmid), and 640 ppm quinine (Qhigh). Researchers and participants were blinded to the solutions and trials were applied in randomized, counterbalanced fashion. RESULTS: Perceived bitterness was different across the treatments (PLAC = 0.3 ± 0.1, Qlow = 2.8 ± 0.5, Qmid = 4.8 ± 0.7, Qhigh = 6.1 ± 0.7) (p = 0.001). 5TSTS time was faster in Qhigh(7.55 ± 0.39 s) compared to PLAC (8.06 ± 0.37 s) (p = 0.02), but was similar to Qlow (7.95 ± 0.32 s) and Qmid (7.87 ± 0.38 s). No differences across treatments existed with lean angle. Electrical activity in the motor cortex was also not changed by quinine consumption. Beta frequency power was greater during Qhigh(7.58 ± 1.21 μV2, p = 0.03) and Qmid (9.25 ± 2.05 μV2, p = 0.01) compared to PLAC (5.08 ± 0.91 μV2) in the premotor cortex. CONCLUSION: Bitter solutions may be effective in improving functional performance during 5TSTS in young healthy adults by altering brain activity in the premotor cortex.

  PublisherDOI

Frequent coauthors

• Stephen P. Bailey

  Elon University

  15 shared

• David J. Baer

  14 shared

• Kim S. Stote

  Albany Stratton VA Medical Center Albany

  13 shared

• David R. Paul

  University of Idaho

  9 shared

• Stephen S. Leonard

  National Institute for Occupational Safety and Health

  9 shared

• Srikant Vallabhajosula

  8 shared

• William V. Rumpler

  United States Department of Agriculture

  8 shared

• Emilize Momplaisir

  North Carolina State University

  8 shared

Education

• Ph.D., Food, Bioprocessing and Nutrition Sciences

  North Carolina State University

  2008

• M.S., Food, Bioprocessing and Nutrition Sciences

  North Carolina State University

  2003

• B.S., Food Science

  North Carolina State University

  2001