ABSTRACT HATHORN, CHELLANI S. Development of a Peanut
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ABSTRACT HATHORN, CHELLANI S. Development of a Peanut-Sweetpotato Ready to Use Therapeutic Food and Evaluation of Peanut Skins in Peanut Products. (Under the direction of Dr. Timothy H. Sanders). Severe acute malnutrition (SAM) affects 20 million children under the age of five. Vitamin A deficiency (VAD) is the leading cause of childhood blindness in the world and an estimated 250,000 to 500,000 children become blind every year. Ready to use therapeutic foods (RUTF) are soft enriched foods containing mostly peanuts, milk powder, and vitamin/minerals. RUTFs were developed to eliminate SAM and incorporating β-carotene rich sweetpotatoes in RUTFs may be a viable way of addressing VAD. The main objective of this work was to develop a peanut-sweetpotato RUTF and evaluate nutritional composition, descriptive sensory analysis and consumer acceptance of formulations containing peanuts/sweetpotato flakes (SPF)/milk powder, and other standard ingredients. A secondary objective was to evaluate the potential of peanut skins to improve nutritional properties and enhance the shelf life of peanut products. Eleven formulations of peanut paste fortified with SPF and milk powder were evaluated for nutritional composition and sensory characteristics. A lexicon incorporating roasted peanut and sweetpotato flavor descriptors was developed. Increased β-carotene and oxidative stability index (ORAC) were observed in the test formulations. In the samples evaluated, β-carotene ranged from 230 to 3870 µg/100g, while ORAC ranged from 4030 to 5025 µMol/100g. The addition of milk powder improved protein quality, resulting in increased concentration of some specific amino acids. From the eleven formulations, two were selected for the evaluation of nutritional composition, flavor using descriptive sensory analysis and consumer acceptance. A commercial RUTF (MANA), and one peanut only formulation were evaluated. The three formulations contained 49/15/20, 28/20/30 and 56/0/30 percentages of peanuts/SPF/milk powder, respectively, and other standard ingredients. β-carotene in 49/15/20 and 28/20/30 was 2040 µg/100g and 3070 µg/100g, respectively. MANA and the 56/0/30 formulation contained 350 µg/100g and 420 µg/100g, respectively. The combination of milk powder with other ingredients used in this study resulted in a more complete amino acid profile than peanuts alone. Formulations containing SPF were characterized by roast peanutty, sweet aromatic, baked sweetpotato/dried apricot/floral aromatics. The formulation containing 15% SPF was one of the two most overall liked by consumers and overall flavor liking was highest in this formulation. To potentially add antioxidants to RUTF’s, peanut skins were incorporated into peanut paste and peanut butter. Peanut skins blended up to 20.0% w/w resulted in increased (P<0.05) total phenolic content of peanut paste from 12.9 to 31.9 mg/GAEg and 14.1 to 28.1 mg GAE/g for peanut butter. Oxygen radical absorbance capacity (ORAC) of peanut paste and peanut butter increased as the concentration of peanut skins increased, and ranged from 4041 to 20063 and 5702 to 20376 µMol Trolox/100g. The addition of low levels of skins did not result in flavor changes but more than 5% peanut skins resulted in a decrease in roast peanut intensity and an increase in woody/hulls/skins, bitter and astringency intensities. Subsequent storage of peanut paste and peanut butter containing skins resulted in a decrease in shelf life inversely related to the concentration of peanut skins added. A study was conducted to identify the cause of reduced shelf life. Oxidative stability index (OSI) of peanut skin oil (1.1-4.1 hrs) was significantly lower (P<0.05) than oil from peanuts (9.8 – 15.7 hrs). Analysis of peanut skins indicated low levels of -tocopherol and high levels of Cu and Fe. OSI, low -tocopherol, and high copper and iron concentrations in peanut skins suggest a cause for reduced shelf-life of peanut products containing peanut skins. © Copyright 2013 by Chellani S. Hathorn All Rights Reserved Development of a Peanut-Sweetpotato Ready to Use Therapeutic Food and Evaluation of Peanut Skins in Peanut Products by Chellani S. Hathorn A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Food Science Raleigh, North Carolina 2013 APPROVED BY: ________________________________ ________________________________ Dr. Timothy H. Sanders, Dr. Lisa O. Dean Committee Chair ________________________________ ________________________________ Dr. MaryAnne Drake Dr. Van Den Truong DEDICATION To my mom and dad ii BIOGRAPHY Chellani Hathorn was born and raised in Lexington, MS. Upon graduating from high school, Chellani went on attend Alcorn State University in Lorman, MS earning a Bachelor of Science in Agriculture. Chellani received a Master of Science in Food Science from Tuskegee University in Tuskegee, AL. Later, Chellani started the PhD program in Food Science at North Carolina State University in Raleigh, NC. iii ACKNOWLEDGMENTS First and foremost, I would like to thank my Lord and Savior, Jesus Christ, for this amazing opportunity. I have grown to become a much stronger individual on this jouney, but I know there is much more to come. I would like to acknowledge my advisor, Dr. Timothy H. Sanders for giving me the opportunity to work in your lab. Every time I visited your office, you always took time to talk to me and see what I wanted or needed. Thank you for encouraging me both academically and personally. I truly appreciate everything you have done for me. Also I would like to acknowledge my committee members, Dr. Lisa Dean, Dr. MaryAnne Drake and Dr. Den Truong. Dr. Dean, thank you for taking time to answer my questions and helping me solve problems. Dr. Drake, thank you for your suggestions and help with the sensory portion of my work. Dr. Truong, thank you for encouraging me throughout my time in school. I am forever grateful to the USDA/ARS Market Quality and Handling Research Unit (MQHRU). Keith, you have such a giving spirit! I truly appreciate all of your help. If I started to list all the ways you have helped, the list would go on. Jim, my fellow Mississippian, thank you for helping me in the lab whenever I needed it. Sabrina, you have always been extremely kind, helpful and you were always ready to answer my questions. Michael, thank you for assisting me with roasting peanuts. Thanks to Dr. Jack Davis, Kristen Price, Dr. Brittany White and Jeff Whaley for their help and assistance. To all of my office iv mates in room 221 (both past and present), thank you for all the laughs and fun times that we had. I would like to thank Judy Cooper for her kind words of encourgaement. Dr. Leon Boyd, thanks for encouraging me to apply to NCSU and I appreciate you stopping by the office to check and see how things were progressing even after you had retired. I would like to acknowledge my parents, Louis Blake and Claranett Hathorn for their prayers, support, sacrifices and always believing in me. Thanks for always being there! To Shintri and Blake, thanks for being the best sister and brother ever! We always have such a great time laughing and talking whenever we are together, as well as when we are on the phone. Adrian, thank you for always being there, pushing me, praying with me and constantly speaking the word of God. You have truly supported me through this process. You are awesome! Danielle, Erica, Dee, and Jessica, thank you for encouraging me and always showing the love of God. You all are such wonderful and supportive friends. I would like to thank the Carter family for their continuous support and love. I’ve been blessed to have many wonderful people in my life. I thank each of you for always loving me and for being there whenever I needed you. I love each of you from the bottom of my heart! v TABLE OF CONTENTS LIST OF TABLES ……………………………………………………………………….....xi LIST OF FIGURES ……………………………………………………………………….xiv CHAPTER 1. LITERATURE REVIEW…………………………………………………...1 Peanuts………………………………………………………………………………………..2 Introduction ………………………………………………………………………..............2 Peanut maturity ……………………………………………………………………..5 Peanut skins …………………………………………………………………………6 Peanut flavor ………………………………………………………………............13 Storage stability and peanut flavor ………………………………………………..18 Bitter taste …………………………………………………………………………20 Transduction of bitter taste ………………………………………………………..21 Bitter - phenolic compounds and tannins …………………………………………22 Astringency ………………………………………………………………………..23 Astringent compounds …………………………………………………………….24 Texture …………………………………………………………………………….25 Texture of peanut products ………………………………………………………..28 Sweetpotato………………………………………………………………………………….30 Introduction ………………………………………………………………………………30 vi Composition ……………………………………………………………………….30 Harvest, curing and processing ……………………………………………………33 Sweetpotato Flakes ………………………………………………………………..34 Descriptive sensory and consumer acceptance ……………………………………37 Flavor constituents ………………………………………………………………...41 Milk powder ………………………………………………………………………………..44 Introduction ……………………………………………………………………….............44 Composition ……………………………………………………………………….45 Oxidation …………………………………………………………………………..47 Flavor ………………………………………………………………………...........47 Flavor as affected by storage ……………………………………………………...48 Ready to Use Therapeutic Foods/Ready to Use Supplementary Foods ...……………....49 Introduction ………………………………………………………………….....................50 RUTF/RUSF ………………………………………………………………………54 Plumpy’nut ………………………………………………………………………..56