Dried Fruits

Phytochemicals and Health Effects

Fereidoon Shahidi, Cesarettin Alasalvar

• Publisher: Wiley-Blackwell
• Year: 2012
• Print ISBN: 9780813811734
• eBook ISBN: 9781118464649
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

Dried fruits serve as important healthful snack items around the world. They provide a concentrated form of fresh fruits, prepared by different drying techniques. With their unique combination of taste/aroma, essential nutrients, fibre, and phytochemicals or bioactive compounds, dried fruits are convenient for healthy eating and can bridge the gap between recommended intake of fruits and actual consumption. Dried fruits are nutritionally equivalent to fresh fruits, in smaller serving sizes, in the current dietary recommendations of various countries. Scientific evidence suggests that individuals who regularly consume generous amounts of dried fruits have lower rates of cardiovascular disease, obesity, various types of cancer, type-2 diabetes, and other chronic diseases. Dried fruits also have the advantage of being easy to store and distribute, available around the year, readily incorporated into other foods and recipes, and present a healthy alternative to salty or sugary snacks.

Dried Fruits: Phytochemicals and Health Effects is divided into three sections preceded by introductory chapters that provide an overview of dried fruits (their composition, phytochemicals and health applications) as well as the cancer chemopreventive effects of selected dried fruits (amla fruits or Indian gooseberries, avocados, berries, mangoes, mangosteens, persimmons, prunes, raisins, kiwi fruits, and other dried fruits). The first section covers the most popular dried berries (blackberries, blackcurrants, blueberries, cranberries, goji berries, mulberries, raspberries, and strawberries); the second section discusses non-tropical dried fruits (apples, apricots, cherries, citrus fruits, figs, nectarines, peaches, pears, prunes, and raisins); and the final section addresses tropical dried fruits (açai fruits, bananas, dates, guavas, papayas, mangoes, passion fruits, and pineapples).

Contributors to this volume are internationally renowned researchers who have provided a comprehensive account of the global perspectives of the issues relating to phytochemicals and health effects of dried fruits. The book will serve as a resource for those interested in the potential application of new developments in dried fruits' nutraceuticals and functional foods. Biochemists, chemists, food scientists/technologists, nutritionists, and health professionals, from academia, government laboratories, and industry will benefit from this publication. Although this book is intended primarily as a reference book, it also summarises the current state of knowledge in key research areas and contains ideas for future work. In addition, it provides easy to read text suitable for teaching senior undergraduate and post-graduate students.

1

Composition, phytochemicals, and beneficial health effects of dried fruits: an overview

Cesarettin Alasalvar and Fereidoon Shahidi

1.1 Introduction

Dried fruits serve as a concentrated form of fresh fruits prepared by different drying techniques. In other words, dried fruits possess much lower moisture content as a large proportion of their original water has been removed, either naturally through sun drying or through the use of specialized dryers or dehydrators. Considering the 2011 global production of commercially important dried fruits (Table 1.1), dates rank first on a global basis with a production of 6,598,000 metric tonnes (MT), followed by raisins (1,170,999 MT), prunes (236,500 MT), apricots (198,917 MT), and figs (105,453 MT) [1]. To the best of our knowledge, little information is available about the production of other dried fruits (açai berries, apples, bananas, black currants, blackberries, cherries, citrus fruits, cranberries, gingers, goji berries, guavas, kiwis, mangoes, mulberries, nectarines, papayas, passion fruits, peaches, pears, pineapples, raspberries, star apples, and strawberries, among others).

Table 1.1 World dried fruits production (metric tonnes)

Dates, figs, prunes, raisins, apricots, peaches, apples, and pears are referred to as “conventional” or “traditional” dried fruits. On the other hand, some fruits such as blueberries, cranberries, cherries, strawberries, and mangoes are infused with sugar solutions (e.g., sucrose syrup) or fruit juice concentrates prior to drying. Some products sold as dried fruit, such as papayas and pineapples, are actually candied fruit [2].

Epidemiologic studies have found an association between dried fruit consumption and diet quality. Raisins may be among the most researched of all dried fruits showing a health benefit [3], followed by dates, prunes, figs, apricots, peaches, apples, pears, and other fruits, which together constitute nearly half of all dried fruits produced in the world each year [2].

This overview chapter summarizes the nutritional significance, phytochemical composition, and potential health benefits of dried fruit consumption and discusses their great potential as medicinal or healthy foods for a number of diseases inflicting human beings.

1.2 Compositional and nutritional characteristics of dried fruits

Dried fruits come in almost as many varieties as fresh fruits. Although raisins, figs, dates, prunes, and apricots are the most common dried fruits in the marketplace, health food stores and local markets offer many more choices such as dried apples, pineapples, berries, mangoes, papayas, and even the exotic dragon fruit. They are rich sources of essential nutrients and health-promoting bioactive compounds. Table 1.2 summarizes the nutritional composition of some dried fruits (apples, apricots, dates, figs, peaches, pears, prunes, and raisins) [4]. Dried fruits are rich in carbohydrates (61.33–79.18 g/100 g) and devoid of fat (0.32–0.93 g/100 g). The most calorie-rich of these fruits are raisins (299 kcal/100 g), followed by dates (282 kcal/100 g). Dried fruits are excellent sources of sugar ranging from 38.13 g/100 g in prunes to 63.35 g/100 g in dates. Fructose and glucose are the main sugars found in all dried fruits, followed by sucrose. Trace amounts of maltose and galactose are found in some dried fruits. Levels of sugar may differ according to drying methods and regional and varietal factors.

Table 1.2 Compositional and nutritional characteristics of some dried fruits (values in per 100 g edible portion)

It is important to note that the high content of dietary fiber (3.7–9.8 g/100 g) found in dried fruits is an important source that helps meet our dietary recommendations (14 g of fiber for every 1000 calories of food consumed each day).This becomes 25–38 g of fiber per day depending on age and gender [5]. On a per serving basis (40 g), dried fruits deliver more than 9% of the daily value of fiber, depending on the fruit [4]. It has been reported that dried fruits (40 g/serving) compare favorably in their fiber content with common fresh fruit (one cup or one fruit serving) options [4, 6].

With respect to nutritional aspects, percentage of recommended dietary allowances (RDA) or adequate intake (AI) of minerals for adult males and females (aged 15–50 years) are also given in Table 1.3. Dried fruits, in general, serve as a reasonable source of copper, iron, magnesium, manganese, phosphorus, and potassium. Among the eight dried fruits listed in Table 1.3, peaches possess the highest mineral content, whereas apples contain the lowest. Consuming 40 g (on a per serving basis) of dried fruits (Table 1.3) supplies 0.6–6.5% of calcium, 8.4–16.4% of copper, 2.1–20.3% of iron, 1.6–8.6% of magnesium, 1.6–11.3% of manganese, 2.2–6.8% of phosphorus, and 3.8–9.9% of potassium for RDA or AI for adults [4, 7–9]. Based on RDA and AI values, dried figs are high in calcium, magnesium, and manganese, whereas dried peaches are good sources of iron and phosphorus. Moreover, apricots are an important source of potassium among the eight dried fruits listed in Table 1.3. On a per serving basis (40 g or about one-fourth cup), dried fruits rank among the top potassium sources in diets around the world [6]. Moreover, on a per serving basis, different dried fruits such as apricots, currants, dates, figs, peaches, prunes, and raisins (40 g serving) compare positively in their potassium content with the 10 most common fresh fruit options such as apples, bananas, grapes, mangos, oranges, peaches, pears, pineapples, strawberries, and watermelons (one cup or one fruit serving) [4, 6].

Table 1.3 Percentage of RDA values for adults (aged 19–50) in 40 g of dried fruits (per serving basis)

Dried fruits contain both water-soluble (betaine, choline, folate, niacin, pantothenic acid, pyridoxine, riboflavin, thiamine, and vitamin C) and fat-soluble vitamins (A, E, and K) (Table 1.2). Among the eight dried fruits listed, prunes are the richest source of vitamin K (59.5 μg/100 g), whereas apricots are the richest source of vitamin A (180 μg/100 g) and vitamin E (4.33 mg/100 g) [4]. Dried fruits, in general, contain a small amount of vitamin C. With regard to RDA of vitamins, 40 g dried fruits provide up to 1.6–12.5% of niacin, 0.8–4.7% of pantothenic acid, 2.2–6.5% of pyridoxine, 2.2–7.6% of riboflavin, and 0.9–26.4% of vitamin K for RDA or AI for adults [4, 8, 10,11]. Prunes are particularly high in vitamin K. Among these eight dried fruits, prunes, apricot, and peaches contain higher amounts of vitamins than other dried fruits (Tables 1.2 and 1.4).

Table 1.4 Percentage of RDA values for adults (aged 19–50 years) in 40 g of dried fruits (per serving basis)

Despite the fact that dried fruits contain all indispensable amino acids (except tryptophan in pears), in general, they are not good sources of amino acids due to their low protein content (Table 1.2).

In summary, the following are some nutritional facts about dried fruits [12]:

• Dried fruits are low in their fat and sodium content and, as expected, devoid of trans-fats and cholesterol [4].
• Dried fruits are good sources of dietary fiber and potassium. Among all fruits, they are among the top five contributors of fiber and potassium [5].
• Dried fruits provide essential nutrients that are otherwise low in today's diet, such as vitamin A (apricots and peaches), calcium (figs), vitamin K (prunes), boron (raisins and prunes), iron, and copper [4, 13].
• Traditional dried fruits have no added sugars. Most traditional dried fruits contain low amounts of sucrose; their sugar content is in the form of fructose and glucose [4].

1.3 Phytochemicals in dried fruits

Phytochemicals are defined as nonnutritive, naturally occurring, biologically active, and chemically derived compounds found in the plant kingdom. More than several thousands of individual phytochemicals have been identified in plant-derived foods and their by-products, but a large percentage of phytochemicals still remain unknown and need to be identified before we can fully understand the health benefits of phytochemicals in whole foods. Dried fruits are highly nutritious and provide a range of phytochemicals such as phenolic acids, flavonoids (anthocyanidins, flavan-3-ols, flavones, flavonols, and isoflavones), phytoestrogens, and carotenoids, among others [3,4, 14–28]. They, in general, contain traces or undetectable amounts of proanthocyanidins [29]. Proanthocyanidins detected in plums and grapes are absent in prunes and raisins, which suggests that these compounds are degraded during the drying process [30].

Dried fruits are excellent sources of phenolic compounds in the diet [31–35]. These make up the largest group of plant phytochemicals in the diet and they appear to be, at least in part, responsible for the health benefits associated with diets abundant in fruits and vegetables. Phenolic compounds contribute most to the antioxidant activity of fruits and vegetables [36] and have a multitude of functional capaci...

Table of contents

• Cover
• Series
• Title Page
• Copyright
• List of Contributors
• Preface
• Chapter 1: Composition, phytochemicals, and beneficial health effects of dried fruits: an overview
• Chapter 2: Cancer chemopreventive effects of selected dried fruits
• Part 1: Dried Berries
• Part 2: Nontropical Dried Fruits
• Part 3: Tropical Dried Fruits
• Index