eChapters

Purpose: The organic acids present in fruits and vegetables influence the flavour, colour, keeping quality and maturity. The maturity standards are determined by the acid and sugar ratio. The total acidity (citric acid) is determined by titrating the juice against standard alkali solution.

Equipments and chemicals: 10 ml., pipette, 25ml. Burette, small glass funnel, dropper, juice extractor, distilled water, 100ml. volumetric flask, burette stand, beaker, N/10 sodium hydroxide, filter paper, phenolphthalein indicator (one gram of phenolphthalein in 100ml. of 95% ethyl alcohol)

Principle: Sample extract in oxalic acid is titrated against standard sodium 2, 6 dichlorophenolindophenol dye to a faint pink colour which persists for 5-10 seconds.

(Indophenols Method)

Purpose: The ash content of plants represents the deposition of minerals elements in the plant or in its parts. The value of ash content in the plant tissue indicates the health of the plant. Plant ash is also used both in qualitative and quantitative estimation of mineral elements.

Material and Equipments: Crucible, oven, chemical balance and weight box.

54.1. Aim

To determine crude fibre in given samples.

54.2. Theory

Fibres can be classified into four categories like crude fibre (cellulose); acid detergent fibre (cellulose + lignin); neutral detergent fibre (cellulose + lignin + hemicelluloses) and total dietary fibre (Cellulose + lignin + hemicelluloses + pectic substances). Crude fibre is the organic residue of a sample. A fat free sample is treated with boiling sulphuric acid and subsequently with sodium hydroxide. The residue after subtraction of ash is regarded as crude fibre.

54.3. Reagents/ Apparatus/Glassware

1. 0.255 N Sulphuric acid solution

2. 0.313 N Sodium hydroxide solution

3. 10% Potassium sulphate solution

4. Ethanol

Fructose, a keto-hexose (called as fruit sugar), is usually accompanied by sucrose in fruits and estimated by the methods of Ashwell (1957).

Materials

Resourcinol reagent: Dissolve 1g resorcinol and 0.25 g thiourea in 10 ml glacial acetic acid. This is stable in the dark.

Dilute HCl: Mix five part of conc. HCl with one part of distilled water.

Standard fructose solution: Dissolve 50mg of fructose in 50 ml water. Dilute 5 ml of this stock soln. to 50 ml for a working standard.

Mechanical damage is inflicted on seeds during harvesting, threshing drying, processing and handling. Injury may occur from any kind of physical abuse. Threshing abuse probably is most serious but, seed conditioning and handling also contribute to seed injury. High temperatures during drying or drying too quick or excessively can cause injury. Susceptibility to mechanical injury increases as the moisture content of the seed decreases. Effect of all individual impacts received by the seed appears to be cumulative in total seed damage. Cereals are largely immune to mechanical injury presumably because of the protective outer structures, the palea and lemma. Large sized legumes are more suscepitable. Small seeds tend to escape injury during harvest and seeds that are spherical tend to suffer less damage than elongated or irregularly shaped ones.

Preparation of the material: Common minute material for analysis in Waring blender for 1 to 2 minutes. Do not over heat. Pass it through No.60 sieve and put is in airtight container.

Procedure: Take 2 to 3 g sample in duplicate in pre-dried and pre-weighed 7 cm diameter aluminium dishes. Remove the dish cover and put them in vacuum oven and dry for 6 hours at 88°C and 26-22 inch vacuum. During this process, admit to oven a slow current of air (2 bubbles per second) dried by passing H₂SO₄ replace the cover, cool it in desiccators and weigh again.

Principle: Addition of calcium chloride results in the precipitation of pectin as calcium pectate from an acid solution. Calcium pectate is washed with water to make free from chloride and is dried and weighed.

26.1. Aim

To determine the pH of food samples.

26.2. Theory

The hydrogen-ion concentration of a food is a controlling factor in many chemicals and microbiological reactions. Pure water has equal concentration of H+ and OH- ions, each having the value of 1×107g/litre at room temperature that is why water is regarded as neutral. The pH of pure water is 7.0, the solution having pH below 7.0 is regarded as acidic while solution with pH above 7.0 is alkaline. Most fruits and fruit products have pH below 4.0 while vegetable; milk and meat products have pH more than 4.0. The pH value of some fruits and fruit products is given in Table 6.1. Thus, with the increase in acidity in the solution, the pH value decrease and vice versa. However, presence of buffer salts helps in maintenance of pH. Estimation of pH of the food is important as the processing conditions for different food products are categorized on the basis of their pH.

Procedure: Standardize the pH meter with a buffer solution of pH. Take the sample solution in a 100 ml beaker. Put the electrodes in the solution and read on pH meter. After each observation, wipe the electrodes with a piece of cotton soaked in distilled water and rinse the electrodes with water with the help of a wash bottle and dry with filter paper.

Principle: The copper in the Fehling solution is reduced to red, insoluble cuprous oxide in the presence of invert sugars like glucose and fructose. The quantity of sugars solution liquids for complete neutralization of a known quantity of Fehling mixture is determined by titration using methylene blue as the indicator.

(Lane and Eynon Method)

Principle: A weighed sample is dried in an oven at 60-70⁰C up to a period of time when weighing made at 2 hour intervals do not differ by more than 2-3 mg.

23.1. Aim

To determine the total soluble solids in fresh and processed fruit and vegetable products.

23.2. Theory and principle

Total soluble solids (TSS) are determined by means of brix which measures the specific gravity or by using hand refractometer which measures refractive index. Brix is a measure of soluble solids only in case of pure sucrose solutions. Generally, the fruit juices contain more sugar than any other soluble constituent. Hence, brix provides a useful guide of soluble solids or sugar contents. Brix hydrometer is used to determine the percentage of brix in syrup while Abbe refractometer gives refractive index as well as degree brix. The Refractive index of the test solution is measured at 20°C using a refractometer and the soluble solid content is determined by the use of tables correlating refractive index with soluble solids. Generally, hand refractometer is used for determining TSS in food samples in fruit processing units (Table 3.1).

Purpose: The estimation of total soluble constituents gives the approximate amount of water soluble substance present in the sample. Among the various soluble substances the amount of sugar is 80-85 percent. The TSS value is roughly considered to be the amount of sugar and soluble minerals present in fruits and vegetables. The total soluble solid content can be determined by hand refrectometer.

Material and equipments: Hand refrectometer, juice, muslin cloth or tissue paper and glass rod.

1. VARIETY

Variety is a seed/crop which suit the prevailing agroclimatic conditions, high yielding and possessing desirable attributes such as disease resistance, earliness and grain quality. Similarly, the seed should be pure, appropriate classes, and obtained from an authorised official agency.

2.1 Introduction

Greenhouses are used mainly for cultivating vegetables and fruits during the off-season to provide favorable growing conditions. Proper management of the greenhouse structure is necessary to create these off-seasonal favorable conditions for plants. Factors like site selection, location, atmospheric conditions, cropping pattern, and structure of the greenhouse are considered during the development of a greenhouse. The National Committee on the use of Plastics in Agriculture (NCPA-1982) suggests conducting site-specific greenhouse technology trials before implementation across the nation.

1. Introduction

Jackfruit is a fruit crop that is under appreciated and neglected. The jackfruit (Artocarpus heterophyllus Lam.) is a member of the Moraceae family. India is the world’s greatest cultivator and producer of jackfruit, also known as the poor man’s fruit because it grows more in rural than metropolitan areas. It is a pretty huge tree that bears the world’s largest edible fruit. The jackfruit is a tropical fruit native to Southeast Asia. It is thought to have originated in India’s rainforests, in the Western Ghats, and is now widely farmed throughout the region’s lowlands. The leading jackfruit producers in the world include Bangladesh, India, Myanmar, Nepal, Thailand, Vietnam, China, the Philippines, Indonesia, Malaysia, and Sri Lanka. Jackfruit can be found in East Africa, Brazil, and Caribbean nations such as Jamaica. Bangladesh’s national fruits are the jackfruit, mango, and banana.

ABSTRACT

Owing to paucity of available genetic / molecular markers, onion breeding still relies heavily on phenotypic selection methods. DNA markers can provide plant breeders genetic information for indirect selection of plants. All the DNA based procedures require high quality plant genomic DNA. Abundance of polysaccharides and phenolics present in plant tissue often impede PCR amplification. The polysaccharide contaminants can also produce downstream problems by inhibiting many of the enzymes that are employed in subsequent analysis and cloning. RFLP based markers in Allium species pose certain problems due to relatively large size of the genome compared to most other herbaceous crops. As an alternative, RAPD would prove advantageous in genetic analysis of Allium. Here we present our results on optimization of DNA extraction in onion to get amplifiable quality of DNA for further RAPD analysis. Leaf samples were collected from the onion germplasm maintained at Indian Institute of Horticultural Research (IIHR), Bangalore. Dried leaf protocol was suitably modified to obtain fair quality of DNA. After varying each of the ingredients of the extraction buffer we arrived at the optimal extraction buffer, which resulted in good quality DNA. Quality was analyzed by subjecting the DNA to agarose gel electrophoresis and restriction digestion. Extracted genomic DNA was quantified with ‘Hoefer’s Dynaquant’ (Pharmacia, USA). The DNA quantity ranged between 160-2400mg/gm of dried powder. The standardized 25ml PCR mixture contained template DNA (25ng), 5 pmol of primer (Operon Tech. Inc., Alameda), 2mM MgCl₂, I unit of Taq polymerase (Bangalore Genei), with 10x buffer along with 200 mM each of dNTPs. Amplifications were performed in thermal cycler (MJ Research, PTC 100) for 45 cycles after an initial denaturation of 95°C for 3 minutes. In each cycle denaturation for one minute at 95°C, annealing for one minute at 35°C and extension for two minute at 72°C was programmed with final extension step at 72°C for 5 minutes. This fine tuned protocol resulted in clear, informative RAPD profile.

1. INTRODUCTION

India is blessed with all types of vegetation because of the diversified climatic and physiographic factors like tropical, subtropical, temperate and alpine. Due to its wide ranging environmental regimes and diverse biological communities, it is one of the world’s 12 “Mega diversity” nations. Out of nearly 425 families of flowering plants in the world, 328 families with 21,000 species are found in India. Further, in India about 20.64 % area is under forest where various species of trees are found, depending upon the climatic conditions.

There are about 29 species of pine which produce edible nuts and utilized at least by indigenous tribal culture in the world. Most of these nut bearing pines are haploxilon (soft) pines, although several species are of diploxilon (hard) pine group. Spain is the largest producer of Pinus pinea and China is the largest producer and exporter of Pinus koriences and Pinus sibrica nuts. Some of the famous edible pine nut species are listed in Table 1. Chilgoza (P. gerardiana Wall.), commonly known as ‘chilgoza’ or ‘Neoza’ is a member of genus Pinus that maintains a very unique position of being an integral part of the vibrant, but fragile ecosystems of the great Himalayas in the Indian sub-continent. The chilgoza pine is the only pine which is of immense social forestry importance. The earning for the bread and butter of most of tribals in HP is from the chilgoza nuts. Further, it also forms an important part of their diet as well as an item essential for some social obligations. Tribals are still adopting the age old practices for chilgoza nut extraction and further their selling to the agents at throw away prices during peak season of nuts.

Tomato (Solanum lycopersicum L.) is one of the most important vegetable crops cultivated in the world. It is used as raw in salads and also used as cooked vegetable in the preparation of curries. Processed items such as tomato puree, ketchup, pickle, chutney, whole peeled tomatoes and tomato powder are also consumed considerably. It is a rich source of Vitamins A & C. Lycopene and other flavonoids in tomato serve as good source of antioxidants. Tomato occupies 5 million hectares with a productivity of 34t/ha. in the world. In India it is cultivated in an area of 0.88 million hectares with productivity of 21 t/ha.