Postharvest Biology and Technology of Tropical and Subtropical Fruits

Açai to Citrus

Elhadi M. Yahia

• Publisher: Woodhead Publishing
• Year: 2011
• Print ISBN: 9781845697341
• eBook ISBN: 9780857092762
• Topic: Business
• Subtopic: Agribusiness
• Index: Business

While products such as bananas, pineapples, kiwifruit and citrus have long been available to consumers in temperate zones, new fruits such as lychee, longan, carambola, and mangosteen are now also entering the market. Confirmation of the health benefits of tropical and subtropical fruit may also promote consumption further. Tropical and subtropical fruits are particularly vulnerable to postharvest losses, and are also transported long distances for sale. Therefore maximising their quality postharvest is essential and there have been many recent advances in this area. Many tropical fruits are processed further into purees, juices and other value-added products, so quality optimization of processed products is also important. The books cover current state-of-the-art and emerging post-harvest and processing technologies. Volume 1 contains chapters on particular production stages and issues, whereas Volumes 2, 3 and 4 contain chapters focused on particular fruit.Chapters in Volume 2 review the factors affecting the quality of different tropical and subtropical fruits from açai to citrus fruits. Important issues relevant to each product are discussed, including means of maintaining quality and minimizing losses postharvest, recommended storage and transport conditions and processing methods, among other topics.With its distinguished editor and international team of contributors, Volume 2 of Postharvest biology and technology of tropical and subtropical fruits, along with the other volumes in the collection, will be an essential reference both for professionals involved in the postharvest handling and processing of tropical and subtropical fruits and for academics and researchers working in the area. - Along with the other volumes in the collection, Volume 2 is an essential reference for professionals involved in the postharvest handling and processing of tropical and subtropical fruits and for academics and researchers working in the area - Reviews the factors affecting the quality of different tropical and subtropical fruits from açai to citrus fruits - Important issues relevant to each particular fruit are discussed, including means of maintaining quality and minimising losses postharvest, recommended storage and transport conditions

1

Açai (Euterpe oleracea Martius)

C.M.G. Bichara, Federal Rural University of Amazonia, Brazil

H. Rogez, Federal University of Pará, Brazil

Abstract:

Euterpe oleracea Martius (açai palm) is a palm tree that is widespread in the Amazonian region. The juice of E. oleracea fruits, known as açai, is viscous (approximately 8 to 15% dry matter) and is typically prepared by macerating the fruits and adding water while the pulp is extracted. Açai juice is the most commonly consumed beverage in the Amazon region, where individual consumption can reach one liter per day. The juice presents several potential health benefits for consumers, mainly due to its high concentration of polyphenols. High concentrations of anthocyanins (mainly cyanidin-3-glucoside and cyanidin-3-rutinoside) are responsible for the black-purple color of açai juice.

Key words

Euterpe oleracea

açai

polyphenols

postharvest

1.1 Introduction

1.1.1 Origin and botany of the açai palm

The American literature mentions 30 species of the Euterpe genus in Central and South America (Moore, 1973; Uhl and Dransfield, 1991). Euterpe oleracea Martius is a palm tree that is found throughout the Amazon basin and is particularly abundant in the Eastern Amazon. The species occurs in floodplains, on land and in swampland soils. The açai palm often grows alongside other palm trees, typically alongside another palm from the Amazon, the buriti (Mauritia flexuosa). Floodplain soils are, from a biological point of view, favorable for the development of hygrophilic vegetation species like the açai palm, not only because of the humid soil but also because of the greater light intensity due to the limited vegetation cover (Pires, 1973; Cavalcante and Johnson, 1977). The açai palm forms a multi-stem clump structure as it grows. E. oleracea grows in the shape of a big tree shoot (Plate Ia: see colour section between pages 244 and 245) that is composed of stems. Fruiting occurs throughout the year, with a period of higher production occurring between July and December, when it is less humid. During this period, the ripeness of the fruit is also more homogeneous. Fruit production begins when the palms are three years old, and the trees become fully productive three years later (Rogez, 2000).

The stem of the açai palm is smooth, slim, generally upright and gray in color. In the adult stage it is of medium height (10 to 15 meters) and has a diameter of 12 to 18 cm. The apex is composed of a crown of nine to 15 leaves. The mature leaf has a petiole measuring 20 to 40 cm and a total length of 2 to 3.5 meters. The leaves are pinnately divided, with 50 to 80 regularly spaced green and glabrous segments or leaflets, each measuring 40 to 80 cm in length and 4 to 5 cm in width. Six to 11 leaves are shed each year; the greater the number of leaves shed, the greater the fruit production (Castro, 1992). The thick and wide base of the petiole that surrounds the tree at the crown is called the sheath. The section of the stem equivalent to the sheath is cut and processed. It is traded as palm heart, a product that is widely recognized in Brazil and around the world. The açai palm’s inflorescence consists of branches with a variety of male and female flowers that grow in bunches after the fruit has developed (Plate Ib: see colour section between pages 244 and 245).

1.1.2 Fruit morphology and structure

The açai fruit has a globular, round shape, with a diameter of 1 to 2 cm and a weight of 0.8 to 2.3 g. It is composed of core and pulp. The fruit pulp represents 5 to 15% of the fruit’s volume, varying according to the origin and maturity of the fruit (Plate Ic: see colour section; Rogez, 2000). Each fruit has a core that is surrounded by a fibrous tuft of feathers, covered by a thin greasy cuticle. The core has a small and solid endosperm, which is attached to the tegument. The pericarp is partially stringy, rich in silica and poor in lipids, proteins, and starch. At maturity, the endosperm is rich in cellulose, hemicelluloses, and inulin crystals; however, before the fruit reaches maturity, it is rich in lipids. The embryo is small, with a cotyledon that is rich in starch grains, and poor in inulin crystals (Rogez, 2000).

As already mentioned, fruit are more abundant from July to December, in the season that is less rainy. This is also when the tuira fruit (fruit at the ideal stage of maturation – see section 1.2.1), are produced. The tuira fruit, identifiable by their waxy white macula, provide a juice of greater quality (Cavalcante, 1976). All fruit varieties (i.e. green, tinga, black varieties) are green before maturing. Fruits of the green and tinga varieties remain green after maturation, but fruits of the black variety, which is the most abundant (more than 95% of the market) become dark reddish – blue. The variety of fruits differs according to the phenotypic characteristics of the plant. It is the presence or absence of anthocyanins that is responsible for the change in color (Rogez, 2000).

1.1.3 Worldwide importance and economic value

There is currently increased interest in açai fruit production. Açai was initially only produced and sold locally, but it is now sold in new markets internationally, and has become a significant source of jobs and income. In 2006, 500 000 tons of açai fruit was produced, and consumption of the juice reached 240 000 tons in Pará state (Northern Brazil), 58 000 tons in the rest of Brazil, and 12 000 tons abroad (Santana and Costa, in press).

The US has the largest functional food and beverage market in the world and it is expected to have an annual growth rate of 6.1% between 2007 and 2012. Concern about health is driving a number of sub-trends in the US market and fuelling interest in certain ingredients, such as low-calorie sweeteners, fiber, probiotics, omega fatty acids, and antioxidants. Antioxidants are turning up in all sorts of food products, from beverages to baby food. These products are using ‘superfruits’ as ingredients, which are fruits that are high in antioxidants and have high Oxygen Radical Absorbing Capacity (ORAC) values. Common superfruits include blueberries, pomegranate, açai and cranberry. Globally, between 2003 and 2008 pomegranate and açai appeared in the greatest number of new products (Evani, 2009). These trends demonstrate that consumers are increasingly looking out for antioxidants, which they associate with health promotion, mainly in terms of the prevention of cancer and cardiovascular diseases, neutralization of free radicals and memory improvement. Although the global ‘health foods’ industry grows by only 4.5 to 5% each year, sales of products that are recognized as ‘functional’ through ‘claims’ are expected to grow by 12 to 14% annually (ABIA, 2008).

1.1.4 Culinary uses

Açai or açai drink is made from the fruit. This drink is traditionally prepared in two steps. First, the fruit is softened in warm water, and then it is mechanically depulped, as water is added. In the Amazon region, açai is frequently consumed with mandioca flour, fish, shrimp or meat, the basic foods of the local people who live along the rivers in Amazonia (...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributor contact details
• Woodhead Publishing Series in Food Science, Technology and Nutrition
• Foreword
• Chapter 1: Açai (Euterpe oleracea Martius)
• Chapter 2: Acerola (Malpighia emarginata DC.)
• Chapter 3: Achachairú (Garcinia humilis (Vahl) C. D. Adam)
• Chapter 4: Ackee fruit (Blighia sapida Konig)
• Chapter 5: Aonla (Emblica officinalis Gaertn.)
• Chapter 6: Arazá (Eugenia stipitata McVaugh)
• Chapter 7: Assyrian plum (Cordia myxa L.)
• Chapter 8: Avocado (Persea americana Mill.)
• Chapter 9: Bael (Aegle marmelos (L.) Corr. Serr.)
• Chapter 10: Banana (Musa spp.)
• Chapter 11: Black sapote (Diospyros digyna Jacq.)
• Chapter 12: Breadfruit (Artocarpus altilis [Parkinson] Fosberg)
• Chapter 13: Breadnut (Artocarpus camansi Blanco)
• Chapter 14: Cactus pear (Opuntia species)
• Chapter 15: Cajá (Spondias mombin L.)
• Chapter 16: Camu-camu (Myrciaria dubia Kunth McVaugh)
• Chapter 17: Cape gooseberry (Physalis peruviana L.)
• Chapter 18: Carambola (Averrhoa carambola L.)
• Chapter 19: Cashew apple and nut (Anacardium occidentale L.)
• Chapter 20: Chili plum (Spondias purpurea var. Lutea)
• Chapter 21: Citrus spp.: orange, mandarin, tangerine, clementine, grapefruit, pomelo, lemon and lime
• Index