Pineapple


Introduction


Pineapple (Ananas cosmosus) is a tropical fruit which grows in countries which are situated in the tropical and sub-tropical regions. It is native to Central and South America.

Pineapple belongs to the Bromeliaceae family and grows on the ground. It can grow up to 1m in height and 1.5m wide. Other bromeliads live on trees (epiphytes). There are many cultivars of Ananas, but the predominant one is 'Smooth Cayenne' (Samson, 1986). Total pineapple production worldwide is around 16 to 18 million tons (Carvalho et al., 2008; Fernandes et al., 2008). There are several countries (e.g. Thailand, Brazil, India, Phillipines and China) which contribute to the total production.

pineapple.jpg
Pineapple plant, from Google image.
Pineapple is an important food which can be eaten fresh or eaten in a processed form. It is composed of nutrients which are good for human health. This is due to researches carried out on the relationship between nutrients in pineapple and human health. Processing pineapple in industries can leave a lot of waste which can cause serious environmental problems. Researches have been carried out recently to counteract this problem.

Uses and Compositon

Pineapple is largely consumed around the world as canned pineapple slices, chunk and dice, pineapple juice, fruit salads, sugar syrup, alcohol, citric acid, pineapple chips and pineapple puree. It is also exported to other countries as a fresh product. Sixty percent of fresh pineapple is edible (Samson, 1986).

Pineapple composition:
Table 1. Chemical composition of the edible portion of pineapple (all varieties) (the data from USDA Nutrient Database)

Nutrient
Units
Value per 100 grams
Proximates


Water
g
86.00
Protein
g
0.54
Total lipid (fat)
g
0.12
Ash
g
0.22
Carbohydrate, by difference
g
13.12
Fiber, total dietary
g
1.4
Sugars, total
g
9.85
Sucrose
g
9.85
Glucose (dextrose)
g
5.99
Fructose
g
1.73
Vitamins


Vitamin C, total ascorbic acid
mg
47.8
Vitamin A, IU
IU
58
Vitamin A, RAE
mcg_RAE
3
Other


Carotene, beta
mcg
35

Pine_pic2.jpg
Pineapple fruit, from Google image.
Pineapple mainly contains water, carbohydrates, sugars, vitamins A, C and carotene, beta. It contains low amounts of protein, fat, ash and fibre. Pineapples contain antioxidants namely flavonoids, vitamin A and C. These antioxidants reduce the oxidative damage such as that caused by free radicals and chelating metals. It also has the enzyme complex protease (bromelain). Bromelain contains peroxidase, acid phosphate, several protease inhibitors and organically bound calcium (Tochi et al., 2008).

Processing


Processed pineapple is a popular product which is exported by countries which produce pineapple. Brazil is considered the main pineapple producing country in the world since 2005 (Carvalho et al., 2008). During processing, nutritional quality of pineapple can be reduced but there are recent reasearches carried out which uses new technologies which tries to retain the nutritional quality of the pineapple fruit. This is to meet the consumer demand for healthy, nutritious and "natural" products (Deliza et al., 2005).

Some of the processing methods using the new technologies are as follows:
i. Vacuum frying - a dehydration process that produces healthy fruit snacks (pineapple chips) which partially preserve the fruits original colour and nutritional compounds and have a high hydrophilic antioxidant capacity (Perez-Tinoco et al., 2008).

ii. Radiation processing - a dose of 2KGy did not affect significantly the nutritional value as well as the sensory quality of minimally processed pineapple (Hajare et al., 2006).

iii. Thermal processing - helps in the improvement of colour, as a quality attribute of processed pineapple puree. This is made possible by the increase in knowledge of kinetic of colour change (Chutintrasri and Noomhorm, 2007).

iv. Ultrasound - This is a pre-treatment for drying of pineapple. Drying of pineapple reduces post-harvest loss of fruits and also a process to produce dried fruits, which can be directly consumed or become part of foodstuffs like cakes, pastries and many others. This method has affected the sugar gain of pineapples during the pre-treatment and also has affected the water effective diffusitivity of pineapples during air-drying process (Fernandes et al., 2008).

v. Osmotic evaporation - this is a process whereby pineapple juice is concentrated at moderate temperatures and pressures with good nutritional and sensory qualities. This process has minor changes in the concentrated juices which makes it more preferable (Hongvaleerat et al., 2008).

vi. High pressure technology - This method is used in food processing where food borne micro-organisms and enzymes are inactivated at low temperature, without the need for chemical preservation. This is done in fruit juice processing to preserve most of the nutritional qualities similar to a fresh product (Deliza et al., 2005).

Utilisation of Pineapple waste


Pineapple waste is a by-product of the pineapple processing industry and it consists of residual pulp, peels and skin. These wastes can cause environmental pollution problems if not utilised. Recently there are investigations/studies carried out on how to utilise these wastes.

Pineapple peel is rich in cellulose, hemicellulose and other carbohydrates. Ensilaging of pineapple peels produces methane which can be used as a biogas. Anaerobic digestion takes place and the digested slurry may find further application as animal, poultry and fish feeds (Rani and Nand, 2004).

Correia et al (2004) investigated the ability of Rhizopus oligosporous to produce enhanced levels of free phenolics from pineapple residue in combination with soy flour as potential nitrogen source. From this investigation, they established a relationship between antioxidant activity, ß-glucosidase and total phenolic content in these pineapple/soy flour extracts. They will further investigate these extracts but from this, the value of pineapple wastes can be enhanced.

Bromelain is present in pineapple wastes. Hebber et al (2008) carried out a study where they use Reverse micellar extraction (RME) technique to extract and purify bromelain from pineapple wastes. They found that CTAB/isooctane/hexanol/butanol system resulted in a fairly good extraction of bromelain from pineapple core.

Therapeutic Application


In the tropics, pineapple is grown and used as a medicinal plant. Pineapple contains the enzyme bromelain (protease) which has several therapeutic properties including malignant cell growth, thrombus formation, inflammation, control of diarrhoea, dermatological and skin debridement (Tochi et al., 2008). According to Tochi et al, available evidence indicates bromelain is well absorbed orally with its therapeutic effects being enhanced in a dose dependent manner and if successfully incorporated in foods, it could become more acceptable as a nutraceutical product than it now is.

Conclusion


Pineapple is a tropical fruit which is consumed fresh or in a processed form. It contains nutrients which are good for human health. It also contains antioxidants and protease. It has therapeutic properties: malignant cell formation, thrombus formation, inflammation, control of diarrhoea, dermatological and skin debridement. As pineapple contains bromelain (protease), it can be incorporated into foods which is an advantage to human health when taken orally.

Processed pineapples are consumed worldwide and processing industries are trying out or using new technologies to retain the nutritional quality of the pineapple fruit. This is to meet the demand of consumers who want healthy, nutritious and natural products. Pineapple wastes from these processing industries can be utilised to produce methane, animal feed, phenolics and bromelain.

References