H: Health, Nutrition, & Food Development of an Ingredient Containing Apple Peel, as a Source of Polyphenols and Dietary Fiber Carolina Henr´ ıquez, Hern´ an Speisky, Italo Chiffelle, Tania Valenzuela, Manuel Araya, Ricardo Simpson, and Sergio Almonacid Abstract: Apple peel is a waste product from dried apple manufacture. The content of phenolic compounds, dietary fiber, and mineral are higher in apple peel, compared to other edible parts of this fruits. The objective of this study was to develop an ingredient from Granny Smith apple peel, using a pilot scale double drum-dryer, as drying technology. The control of all steps to maximize the retention of phenolic compounds and dietary fiber was considered. Operational conditions, such as drying temperature and time were determined, as well as important preprocessing steps like grinding and PPO inhibition. In addition, the physical–chemical characteristics, mineral and sugar content, and technological functional properties such as water retention capacity, solubility index, and dispersability among others, were analyzed. A simple, economical, and suitable pilot scale process, to produce a powder ingredient from apple peel by-product, was obtained. The drying process includes the application of ascorbic acid at 0.5% in the fresh apple peel slurry, drum-dryer operational conditions were 110 ◦ C, 0.15 rpm and 0.2 mm drum clearance. The ingredient developed could be considered as a source of phenolic compounds (38.6 mg gallic acid equivalent/g dry base) and dietary fiber (39.7% dry base) in the formulation of foods. Keywords: apple peel, dietary fiber, drum-dryer, ingredient, phenolic compounds Practical Application: A method to develop an ingredient from Granny Smith apple peel using a pilot scale double drum-dryer as drying technology was developed. The method is simple, economical, feasible, and suitable and maximizes the retention of phenolic compounds and dietary fiber present in the raw matter. The ingredient could be used in the formulation of foods. Introduction Apples are a significant part of the human diet. In addition, they have been identified as one of the main dietary sources of antioxi- dants, mainly phenolic compounds, such as flavonoids and pheno- lic acid; and they also possess high antioxidant capacity (Wolfe and others 2003; Khanizadeh and others 2008). In Chile, apple trees are one of the most important fruit trees, and commercial apple production has reached 1.3 million ton/y (ODEPA 2009). Around 60% of this production is destined for exports, mainly as fresh pro- duce, while the rest is processed to juice concentrates, frozen, and dried products. The dried-apple processing generates apple peel as waste product. Industrially, apples are peeled mechanically, and the peels are typically used as compost or in the production of juice. It is estimated that approximately 9000 metrics tons of peels are generated annually, as a result of apple processing. MS 20091033 Submitted 10/16/2009, Accepted 4/16/2010. Author Henr´ ıquez is with the doctorate program, Univ. de Chile, Santiago, Chile. Authors Henr´ ıquez, Simpson, and Almonacid are with Centro Regional de Estudios en Alimentos Salud- ables, Valpara´ ıso, Chile. Author Speisky is with Inst. de Nutrici´ on y Tecnolog´ ıa de los Alimentos, Univ. de Chile, Santiago, Chile. Authors Chiffelle and Valenzuela are with Dept. de Agroindustrias y Enolog´ ıa, Facultad de Ciencias Agron´ omicas, Univ. de Chile, Santiago, Chile. Author Araya is with Centro de Investigaci´ on Agr´ ıcola y Ambiental, Univ. de Vi˜ na del Mar, Vi˜ na del Mar, Chile. Authors Simpson and Almonacid are with Dept. de Ingenier´ ıa Qu´ ımica y Ambiental, Univ. T´ ecnica Fed- erico Santa Mar´ ıa, Valpara´ ıso, Chile. Direct inquiries to author Henr´ ıquez (E-mail: carolinahenriquez@creas.cl; sergio.almonacid@usm.cl). Several researches have determined that the antioxidant con- centration and antioxidant capacity of the apple peel is higher than that of the pulp fractions or the whole fruit, these compo- nents are known to have health-promoting properties (Wolfe and others 2003; Lata and Tomala 2007; Drogoudi and others 2008; Khanizadeh and others 2008). In addition, several researches have reported that the dietary fiber and the mineral content are higher in apple peel as compared to other edible parts of the fruit (Gorin- stein and others 2001; Leontowicz and others 2003). If apple peel shows potential in improving general health when consumed, the development of an apple peel ingredient represents an attractive way to add value to this by-product but, it needs to be processed to a stabilized form. Fruit drying is a very ancient practice; it extends shelf life, and minimizes handling/distribution of raw materials with high moisture content. However, drying causes physical, chemical, and biological changes, especially to natural nutrients because most of the bioactive compounds are relatively unstable to heat (Chantaro and others 2008; Chan and others 2009). On the other hand, re- cent studies have shown that thermally processed foods, especially fruits and vegetables, have higher biological activity due to their various chemical changes during heat treatment, when compared to the food at the fresh state (Chang and others 2006; Mrk` ıc and others 2006). Three scientific reports have shown the development of a powder product from apple peel (Bomben and others 1971; Wolfe and Liu 2003; Rupasinghe and others 2008). Bomben and others (1971), developed an ingredient to enhance flavor in apple pie, but they did not focus on antioxidant components. Wolfe C  2010 Institute of Food Technologists R  H172 Journal of Food Science  Vol. 75, Nr. 6, 2010 doi: 10.1111/j.1750-3841.2010.01700.x Further reproduction without permission is prohibited