20/01/2013 PRESERVATION AND QUALITY Introduction ASPECTS OF SELECTED Changes occurring with processing SRI LANKAN FRUITS Undesirable Desirable Development of Development of toxic pleasing odors, substances flavors and textures Changers to the Inactivation of some texture, flavor, color enzymes and and nutritive value nutritional substances Dharmasena D.A.N. Head/Department of Agricultural Engineering Improvement of the Faculty of Agriculture functionality in food University of Peradeniya ingredients Sri Lanka Introduction Contd. Introduction Contd. • Lime, Tamarind and Garcinia are some of the • The processed products obtained from seasonal fruits those are traditionally used for indigenous preservation methods lead to a cooking in Sri Lanka poor quality end products • The preservation is mainly done by indigenous methods: • Therefore, crops are still considered as Sun drying, Kiln drying, heating, cooling underutilized crops in Sri Lanka (chilling & freezing), reduction of water activity by adding common salt, concentration • The compositional changes with processing & dehydration have not being studied sufficiently • Lime juice for soft drinks is preserved using preservatives Importance of fruits • Citric acid is present up to 8% in its juice. Citric acid is a natural preservative, aids digestion Lime and it also helps in dissolving kidney stones • Lime is well known for Vitamin C – 29mg/100g (35% of the adult requirement), a powerful water soluble • The fruit is also a good source of B-complex natural anti-oxidant vitamins such as pantothenic acid, pyridoxine, • However, this Vitamin C content drops sharply in and folates (The herbal resource, n.d.) processing • The fruit is low in calories, 29 cal/100 g, one of the lowest among the citrus group • Lime also contains a healthy amount of • Rich in dietary fiber (7.36% of RDA) (Kumari, 2010) minerals like iron, copper, potassium, and • Lemon is one of the very low glycemic fruits calcium 1
20/01/2013 Lime processing • In addition, lime extracts and lime essential oils are Citrus aurantifolia frequently used in perfumes, cleaning products, and aromatherapy Drying of Lime • However, lime harvesting is limited to 2-3 months, preservation is a must. Drying characteristics and energy use efficiency of whole lime (black lime) under • But preserved juice is not processed and available for different drying conditions has shown changes sale in the country. Surplus is exported as dried lemon in rate of drying with the drying temperature • The maximum storage duration of fresh lime is three (Kumari, 2010) months but, lime juice is used almost every day for cooking Drying of whole lime Experiment for hydrated lime has shown Changes in the equilibrium moisture content Diameter Drying reduction with drying temperature as follows Temperature ratio Equilibrium Drying Moisture Temperature content Titrable acidity Amaratunga et al., 2003 • Rate of change of color depend on the Drying The Lime Time and Drying Temperature Dried at higher temperatures (70 0 C and 100 0 C) produced black lime Preferred in Saudi Arabia • Drying Temperature …….. Greenness The Lime • Drying Temperature …….. Darkness Dried at lower temperatures (45 0 C 60 0 C) brownish and lighter in color • Fruit initial Moisture .……. Rate of change of colour Preferred by other Gulf countries Amaratunga et al., 2003 2
20/01/2013 Tamarind - Tamarindus Indica Fresh juice storage Importance Sweet and tangy tamarind is one of the widely used • Fresh lime juice can be frozen and store for 9- condiments by South Asians 12 months without any chemical Sticky pulp is a rich source of non-starch polysaccharides or dietary fiber such as gums, hemicelluloses, preservatives. mucilage, pectin and tannins • The frozen product when packaged properly, 100 g of fruit pulp provides 5.1 or over 13% of can be used daily without off flavours & dietary fiber requirement microbial spoilage. Dietary fiber in the food increases its bulk and bowel movements thereby help prevent constipation • However, the Vitamin C content drops The fiber also binds to toxins in the food thereby help drastically during storage. (Dharmasena, 2011) protect the colon mucus membrane from cancer causing chemicals (S hankaracharya, 1998) • It is a good source of minerals like copper, • Dietary fibers bind to bile salts (produced from cholesterol) potassium, calcium, iron, selenium, zinc and and decrease their re-absorption in the colon; thereby help magnesium. Potassium is a component of cell and excretion of “bad” or LDL cholesterol levels from the body body fluids that helps control heart rate and blood pressure • Tamarind is rich in tartaric acid that gives a sour taste to food but is also a very powerful antioxidant (Anti-oxidant • Rich in many vital vitamins including thiamin, E334). It helps body protect from harmful free radicals vitamin A, folic acid, riboflavin, niacin, vitamin-C that are essential for optimum health (Tamarind • Volatile phytochemicals such as limonene, geraniol, safrole, nutrition facts, n.d.) cinnamic acid, methyl salicylate, pyrazine and alkylthiazole s account for the medicinal properties of Tamarind ( Tamarind • There is no scientific evidence on nutritional nutrition facts, n.d.) quality after various traditional processing The colour change of the Tamarind pulp during The Tamarind fruit processing storage The ripen Tamarind fruit 63-69% pulp, moisture (66%), Fresh Tamarind pulp Fresh Tamarind pulp pigments, citric, tartaric, oxalic, Storage malic and succinic acids Colour – Become darker Colour - Brownish red After 1 year change to black Drying Due to leuco – cyanidin and , Due to Millard reaction as the Anthocyanin pigment presence of free amino acids and The wine from The Tamarind The dried pulp reducing sugars in the pulp Tamarind pellets 45-55% pulp,23-30% The antioxidant activity Brix, pH 3.2 solubility by 2 ½ times than (reference - ascorbic acid) the unprocessed tamarind 88% - 96% Marasinghe, 2010 Kumari, 2003 3
20/01/2013 Garcinia Tamarind processing industry at present Garcinia cambogia • The main products are salted & sundried pod packed in consumer packages and Tamarind paste • Tamarind drink is served in some star class hotels • A fruit - Too acid in fresh • Farmers collect pods, de-shell, partially dry under Sun – Tartaric acid ( 10.6 %) and sell them to the collectors at a very low price – Reducing sugars (15%) – Phosphoric acid (1.52%) • Two food processing companies process a small quantity into paste and sold in the city centers. There – Hydroxycitric acid (HCA) is the profit for the value addition is 100- 300% main bio-active chemical • The ability of HCA to reduce blood lipid levels Importance and naturally lower blood cholesterol is another • Hydroxycitric acid or HCA is gaining a reputation property of this amazing natural medicine for assisting weight loss through appetite suppression and by reducing the body’s ability to • More recently, it has been proposed that Garcinia form adipose (fatty) tissue during times of cambogia has a hepatoprotective ability against overeating (believed to be through inhibiting the external toxins, such as alcohol body’s ability to convert carbohydrates to fats) • A recent study reported that Garcinia prevented (The herbal resource, n.d.) liver cells from becoming fibrotic and stopped cell • Garcinol is known to lower acidity in the stomach damage caused by high blood lipid levels (The and protects the gastric mucosa, reducing gastric herbal resource, n.d.) ulcers Garcinia processing Processing industry at present Garcinia pellets • The trees are grown mainly in the home gardens • Variations after boiling in a water bath in the wet zone of Sri Lanka • The well ripen fruits are collected after natural Rinds Pellets fall and sun dried the rind or sometimes dry in a Same weight firewood kiln • Product is purchased by the collectors and finally goes to the wholesale buyers for distribution • Recently, a food processing company has Low acidity Three times acidity as rind introduced the paste to the supermarkets in the Less color More color cities • The main use of the dried fruit is for cooking fish Amaratunga et al., 2003 4
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