Nana Baah Pepra-AmeyawPostdoctoral FellowGrand Challenges InitiativeSchmid College of Science and TechnologyChapman University

Education

Ph.D. Food Science

Michigan State University2014 - 2019

MS Food Science and Technology

Kwame Nkrumah University of Science and Technology2009 - 2013

BS Chemistry

University of Cape Coast2004 - 2008

Research Interests

Chemical interactions between polyphenols, proteins and carbohydrates
Optimization of carbohydrate and protein extraction and isolation from agricultural food products
Valorization of overlooked food resources through development of novel food products

Areas of Interest

Food Chemistry
Cereal Science
Food Engineering & Processing Technology
Food Safety and Quality Control
Statistical Analysis for Food Science

I am a food scientist with a foundation in chemistry. My research employs knowledge and understanding of food chemistry principles to repurpose agricultural waste and create sustainable food systems. Adding value to overlooked resources reduces waste, enhances food availability, and contributes to a circular economy.

I am currently engaged in research to enhance the functionality of protein isolates derived from sunflower meal, a valuable by-product of oil extraction. My work focuses on optimizing the interaction between chlorogenic acid and proteins through innovative chemical and enzymatic techniques.

Beyond research, I enjoy training the next generation of scientists. Whether it’s students or technicians, I am committed to imparting laboratory techniques and fostering a passion for food science.

Teaching

Currently, I teach courses in the Grand Challenges Initiative Program at Chapman University that include

FFC 100: First Year Foundations: Grand Challenges in Science and Engineering
SCI 150: Grand Challenges in Science and Engineering I
SCI-200: Grand Challenges in Science and Engineering II
SCI 250: Grand Challenges in Science and Engineering III

I have also taught Food Science related topics that include

Food analysis
Food Additives and Preservation
Cereals Processing
Food Microbiology
Food Processing Technology
Techniques in Laboratory Analysis
Post-harvest Technology
Inorganic Chemistry
Physical Chemistry
Research Methods
Bioethics
Statistical Methods in Sensory Evaluation

Selected Course Evaluations

Featured Publications

Preventing chlorogenic acid quinone-induced greening in sunflower cookies by chlorogenic acid esterase and thiol-based dough conditioners

Nana Baah Pepra-Ameyaw, Christine Lo Verde, Charles T. Drucker, Cedric P. Owens, Lilian W. Senger

Sunflower seeds contain a high concentration of chlorogenic acid (CGA), which reacts with amino acids to form green pigments under alkaline conditions during food processing. Here, we present two approaches to prevent green pigment formation in sunflower cookies by (A) Addition of free thiols from cysteine and glutathione to sunflower cookie dough and (B) hydrolyzing CGA into caffeic acid and quinic acid with a CGA esterase from Lactobacillus helveticus. Greening occurred more slowly with cysteine; however, neither cysteine nor glutathione prevented greening in the cookies during storage. Chlorogenic acid esterase hydrolyzed CGA in both sunflower butter and flour, resulting in the complete elimination of greening in the sunflower cookies. CGA esterase treatment was efficient as the enzyme could be applied in low amounts (<100 ppm) directly to the dough without needing to pretreat either sunflower butter or flour. Overall, our data indicate that CGA esterase treatment was an effective method of eliminating unwanted greening in sunflower cookies made with baking soda. Long term, these results may represent a method of increasing the use of sunflower butter and flour in high pH baking applications by enabling their use in neutrally colored baked products such as cookies and muffins.

DOI

A highly active esterase from Lactobacillus helveticus hydrolyzes chlorogenic acid in sunflower meal to prevent chlorogenic acid induced greening in sunflower protein isolates

Christine Lo Verde, Nana Baah Pepra-Ameyaw, Charles T. Drucker, Tracie L.S. Okumura, Katherine A. Lyon, Julia C. Muniz, Chloe S. Sermet, Lilian Were Senger, Cedric P. Owens

Chlorogenic acid (CGA) is an ester between caffeic and quinic acid. It is found in many foods and reacts with free amino groups in proteins at alkaline pH, leading to the formation of an undesirable green pigment in sunflower seed-derived ingredients. This paper presents the biochemical characterization and application of a highly active chlorogenic acid esterase from Lactobacillus helveticus. The enzyme is one of the most active CGA esterases known to date with a Km of 0.090 mM and a kcat of 82.1 s−1. The CGA esterase is easily expressed recombinantly in E. coli in large yields and is stable over a wide range of pH and temperatures. We characterized CGA esterase’s kinetic properties in sunflower meal and demonstrated that the enzyme completely hydrolyzes CGA in the meal. Finally, we showed that CGA esterase treatment of sunflower seed meal enables the production of pale brown sunflower protein isolates using alkaline extraction. This work will allow for more widespread use of sunflower-derived products in applications where neutrally-colored food products are desired.

DOI

Efficiency of Locally-Made Edible Coating In Maintaining the Postharvest Quality of Belfast Tomatoes

Mr. Kofi Owusu-Akyaw Oduro, Dr. Abena Boakye, Prof. (Mrs.) Ibok Nsa Oduro, Prof. William Otoo Ellis, Dr. Nana Baah Pepra-Ameyaw

Edible coating technology has been proven to be an efficient and effective method of postharvest preservation. Especially in developing countries, edible coatings and other postharvest technologies are often limited by their high cost. The study aimed to assess the effect of edible coating materials prepared from inexpensive and locally available materials on the postharvest quality of Belfast tomatoes during storage. Different edible coating formulations [M1, M2, M3 and M4] were prepared by varying the concentration of orange peel powder [OP] [0,0.1,0.5,1%] in 10g/L Cassava Starch [CS] and 10g/L Chitosan [CH] coating solutions. Coated and control fruits were stored at 25°C for three weeks. Results showed that the coatings significantly [p<0.05] delayed the changes in weight loss, total Soluble solids, pH and colour compared to uncoated control fruits. At the end of the 3-week storage period, the control fruits recorded the highest weight loss, 25.58 ±1.73 % whiles M4 had the least, 15.14 ±0.30 %. M4 [CH+CS+1OP] significantly maintained the total soluble solids of the tomatoes which increased from 5.71° to 6.68°whiles the control tomatoes increased from 5.71° to 9.09° showing the effectiveness of the coating in maintaining the Total Soluble Solid (TSS) of the Belfast tomatoes. The coated samples also showed some resistance to the colour changes as well as the pH exhibiting the ability to delay the ripening rate in the tomatoes. The edible coating significantly improved the postharvest quality of the Belfast tomato and could have immense impact on other local tomato varieties.

DOI

"Omnia Vincit Labor"

Perseverance conquers all

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