FST 403:FRIUTS AND VEGETABLE TECHNOLOGY FIRST SEMESTER: 20111/2012 Lecturer: Prof. F.O.Henshaw E-mail:[email protected] :[email protected] Mobile phone: +234 8034056311 COURSE OBJECTIVES • FST 403: A compulsory core course for the B.Sc Food Science and Technology programme • At the end of the course students should have: – Acquired an understanding of the nature and properties of the food commodity class, Fruits and vegetables – Acquired an understanding of the post harvest physiological changes in fruits and vegetables – Been exposed to various processing and preservation technologies appropriate for fruit and vegetables – Acquired the required skills in post harvest handling and storage of different fruits and vegetables – Developed critical thinking in relating post harvest handling to quality of fresh and processed fruits and vegetable products COURSE OUTLINE 1 2 3 4 5 6 Classification of Fruits and Vegetable Structure of Fruits and Vegetables Chemical Composition Post harvest Physiology Storage of fresh fruits and vegetable *Controlled Atmosphere *Modified Atmosphere Pretreatment methods: Blanching,sulphiting 7 8 Preservation Technologies Freezing Canning Dehydration sun drying mechanical drying Osmo dehydration Fruit and Vegetable Products Fruit juice and Drinks Fruit leather 9 Sugar Preserves jam, jellies and marmalade 10 Fermented vegetables Pickles, COURSE REQUIREMENTS • 75% attendance of Lectures condition to qualify to seat for final examination. Distribution of course grade Take home assignment 10% In Class Quiz 20% Final Examination 70% CLASSIFICATION • FRUITS: Botanically, are mature ovaries and seed bearing parts of plants • Include: grains, legumes, nuts Cucumbers, olives , mangoes, peppers, tomatoes, citrus, bananas grapes, strawberry, pineapple, • The course however does not include fruits of the grass family such as Cereals, nor the Legumes and nuts • The succulent, high moisture and generally sweet fruits and consumed raw as dessert rather than main meals. • Vegetables: are all other parts of plant which are edible • Include; roots, stems, tubers , leaves etc • These are generally consumed, processed in one form or the other and part of main meal. • This course does not include the starchy roots and tubers • This class of commodity (Fruits and Vegetable) have the following characteristics: high moisture content highly perishable • Post harvest changes in Fruits and vegetable can be desirable e.g Ripening of fruits, which leads to changes necessary for optimum eating quality, colour change, taste and flavour development Structure of Fruits and vegetables • Fruits and Vegetables are made of Simple and Complex cells – Simple cells • Dermal tissue • Parenchyma tissue Dermal tissue is the single layer outside surface of leaves, stem, roots, etc • Parenchyma tissue form majority of the plant tissue and is where the basic molecular activity take place: • Synthesis – Storage of carbohydrate (Photosynthesis) occur. Chemical composition • • • • • • • • Water Carbohydrates Organic acid Fiber Pigments Vitamins Minerals Pectic substances Food Cereals wheat flour, white rice, milled, white maize, whole grain Earth vegetables potatoes, white sweet potatoes Vegetables carrots radishes asparagus beans, snap, green peas, fresh lettuce Fruit banana orange apple strawberries Carbohy Protein drate Fat Ash Water 73.9 78.9 72.9 10.5 6.7 9.5 1.9 0.7 4.3 1.7 0.7 1.3 12 13 12 18.9 27.3 2.0 1.3 0.1 0.4 1.0 1.0 78 70 9.1 4.2 4.1 7.6 17.0 2.8 1.1 1.1 2.1 2.4 6.7 1.3 0.2 0.1 0.2 0.2 0.4 0.2 1.0 0.9 0.7 0.7 0.9 0.9 88.6 93.7 92.9 89.1 75.0 94.8 24.0 11.3 15.0 8.3 1.3 0.9 0.3 0.8 0.4 0.2 0.4 0.5 0.8 0.5 0.3 0.5 73.5 87.1 84.0 • Phytochemicals: non nutrient plant chemicals • Beneficial in disease prevention • Subject of Scientific research on effects on human health Structure of chlorophyll • Chlorophyll –green pigment in plant found in the chloroplast, it is responsible for photosynthesis • Fat soluble • Structurally a porphyrin ring containing magnesium at the center • Displacement of magnesium from the center leads to irreversible pigment change • Change to a gray-green called pheophytin • conversion to pheophytin is favoured by acid Phbut does not occur easily under alkaline condition • Other factors that can cause colour change; – Heat of cooking – Change in pH – Minerals ( zinc and copper) Carotenoids – Red, orange, and yellow pigments in fruits and vegetables – Occur in chloroplast along with chlorophyll,where the chlorophyll dominates – Also in chromoplasts without chlorophyll • Carotenoids are responsible or the colour of tomatoes, peppers, citrus , carrots. • E.g beta –carotene- orange colour, structurally an unsaturated hydrocarbon, the conjugated double bonds are responsible for the colour • Beta-carotene is a precursor of vitamin A (retinol), cleaved by enzyme in the intestinal mucosa to yeild vitamin A • Lycopene- red-orange colour of tomatoes and water melon, • Xanthophylls: yellow orange colour • Derivatives of carotene • Reponsible for colour of yellow maize (cryptoxanthin) • Are vitamin A precursor • Carotenoids are fairly stable , resistant to to heat, pH changes, water leaching since they are fat soluble carotenoids may undergo autoxidation due to large nos of double bonds • Can lead to off-flavour • Antioxidants are usually applied to prevent oxidative changes Structure of carotenoids • Flavonoids:- group of compounds, pigments and colour precursors – Water soluble – E.g; Anthocyanins: red, blue-red, purple pigments such as in blueberries, cherries, raspberries, plums and grapes – structrally Structure of Anthocyanin Structure of e.gs of Anthoxanthin Harvesting, handling and Postharvest changes • Different harvest regimes for Fruits and vegetables • Appropriate maturity stage required for optimum quality • Respiration continue after harvest i.e taking in O2 and giving off CO2, heat and moisture • mechanical damage during harvesting hastens respiration rate and spoilage • Ripening: major post harvest change in fruits • Ripening pattern vary , 2 categories – Climacteric ripen after harvest – Non Climacteric ripen before harvest Climacteric NonClimacteric Apples Banana Mango Peach Plum Pawpaw avocado Citrus Cherry Pineapple melon strawberry • Ripening involves biochemical changes • Enzymic, hormonal • Leading to colour changes, flavour development and optimum eating quality • Storage of fresh produce must seek to control post harvest changes • Controlled storage conditions ca extend the shelf life of produce – Modified atmosphere packaging: Principle is to replace the internal atmosphere of fresh produce by flushing with nitrogen or carbon dioxide and this will lead to extension of shelf life • After flushing the material is sealed in a package to prevent oxygen entry • Normal air composition (78%, Nitrogen; 20% oxygen and 0.03% carbon dioxide) is modififed within the package to: – Reduces respiration – Retards growth of aerobic organisms • Controlled atmosphere storage: • Principle is similar to MA storage involve modification of the gas composition. Reducing oxygen and increasing carbon dioxide in the store • Combined with low temperature.