eChapters

The de    e plant growth, biomass composition, and energy potential.
(a) Nitrogen Determination by Kjeldahl Method
Theory
The Kjeldahl method is one of the most reliable and widely accepted procedures for determining organic nitrogen in biomass samples. It involves the conversion of nitrogen compounds into ammonium sulfate through digestion with concentrated sulfuric acid and a catalyst. The resulting ammonia is then distilled and quantified by titration. This method measures total nitrogen, excluding nitrate and nitrite forms, and is used extensively in plant, feed, and biomass analysis.
The process involves three major steps:
Digestion
Organic nitrogen in the sample is converted to ammonium sulfate by boiling with concentrated sulfuric acid and a catalyst mixture (usually potassium sulfate and copper sulfate) Organic-N+H2SO4?(NH4)2SO4+CO2+H2O
Distillation
The digested sample is made alkaline with sodium hydroxide, releasing ammonia gas, which is distilled and absorbed in a known volume of standard acid.

Introduction Diet and dietary component are proved to be the first line of intervention in prevention and treatment of non-communicable diseases by many studies (R. Vrolix and R.P. Mensink, 2010). Hence the interest has grown in development of functional food product in recent years which provides not only basic nutrients but also has health promoting and diseases preventing properties (Rozek et al., 2010). The Functional Food Center (FFC) defines “functional food” as natural or processed foods that contain known or unknown biologically-active compounds; the foods, as defined, effective, and non-toxic amounts, provide a clinically proven and documented health benefit for the prevention, management, or treatment of chronic disease (Martirosyan et al., 2015). Fiber is classified into two separate groups i.e. soluble which forms gel like substance when comes in contact with water and insoluble is a solid form that does not break down when exposed to water (web 4). Soluble fibers increase total transit time by delaying gastric emptying and also slow glucose absorption, which includes pectins, β-glucans, galactomannan gums, mucilages, and some hemicelluloses (J.H.Cummings and A.M.Stephen 2007). The American Society for Nutrition stated that cereal fibers are modestly associated with a reduced risk of type II diabetes, obesity, and cardiovascular disease (Cho Qi, Fahey Jr & Klurfield, 2013).

In the detection of soil organic carbon a known weight of soil is heated with an excess volume of standard K2 Cr2 O7 in the presence of Con. H2 SO4 . The soil is slowly digested at the low temperature by the heat of dilution of H2 SO4 and the organic carbon in the soil is thus oxidized to CO2 . The highest temperature attained by the heat of dilution reaction produced with the addition of Con. H2 SO4 is approximately 12o C which is sufficient to oxidize the active forms of the soil organic carbon but not the more inert forms of carbon that may be present.

Particle density of soil is the ratio of mass and volume of soil solids. Particle density of soil is an important physical characteristic because the interrelationships of porosity, bulk density and air space, and rates of sedimentation of particles in fluids depend on particle density.

Principle

The determination of particle density (ρ_p) requires the measurement of mass of the solid and its volume. The mass is obtained by weighing the oven- dry soil sample and volume by calculating from the mass and density of water displaced by the sample in a pycnometer. The pycnometer is a glass flask with a ground glass stopper having a capillary opening. The particle density can be calculated using the following equation:

Particle-size distribution is one of the stable soil characteristics, being little modified by agricultural management practices. The particle-size distribution expresses the proportion of various size particles in a soil, especially sand, silt and clay that determine soil texture (Hillel, 2004). Soil texture is closely related to soil physical properties such as water retention and release characteristics, surface area, swelling and shrinking, soil strength and tillage properties. There are two common methods being employed for particle-size (<2.0 mm) analysis namely international pipette method and the hydrometer method. Both the methods are based on Stokes’ law which establishes a relationship between particle size and the rate of sedimentation. Thus, particles are assessed by their settling velocities from suspension in a water solution that can be used to quantify particle size. Size range of soil particles (sand, silt and clay) according to two most adopted systems i.e. U.S. Department of Agriculture (USDA) and International Union of Soil Science (IUSS) formerly known as International Society of Soil Science (ISSS) are given below:

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.

100 ppm ‘P’ : By dissolving oven dry KH2 PO4 salt. Take 0.4393 gm of KH2 PO4 and volume to 1 ltr that gives 100 ppm ‘P’.

Phytochemicals are chemical compounds that occur naturally in plants (phyto means “plant” in Greek). Some are responsible for color and other organoleptic properties, such as the deep purple of blueberries and the smell of garlic. The term is generally used to refer to those chemicals that may have biological significance, for example antioxidants, but are not established as essential nutrients. Scientists estimate that there may be as many as 10,000 different phytochemicals having the potential to affect diseases such as cancer, stroke or metabolic syndrome. The potential of the phytochemicals have large scale pharmacological and biological activities such as antioxidant constituents (hydrolysable tannins, phenolic acid and flavonoids) of the plant materials for the care of health and protection from coronary heart diseases, cancer, anti-carcinogenic and anti-mutagenic effects. Varieties of herbaceous vegetables are protective against various diseases, particularly cardiovascular diseases. These herbaceous plants and species are harmless sources for obtaining natural antioxidants. Antioxidant constituents can delay or inhibit the oxidation of lipids and other compounds by inhibiting the propagation of oxidation chain reaction (Hussain et al., 2011)

Primarily, antioxidant effect is due to phenolic compounds such as phenolic acid, flavonoids and phenolic diterpenes and their mode of action for antioxidant compounds is due to its redox reaction properties which can absorb and neutralize free radicals by quenching singlet and triplet oxygen. Vitamins are organic substances necessary for metabolism. Human diet does not always contain the required amount of vitamins for the normal growth and maintenance of the body function and as such cannot produce enough quantity for their body metabolism, so it can be obtained from fruits, vegetables and foods. Deficiency of vitamins can cause serious human health diseases and sometimes, very small concentrations are required for maintenance of good human health.

Theory

Porosity is a physical property characterizing the texture and the quality of dry and intermediate moisture foods. Porosity means inter-granular space. It is the measure of void space between the materials. Porosity may be defined as the percentage of volume of inter-grain space to the total volume of grain bulk. Porosity depends on size, shape, dimension, and roughness of grain surface.

The porosity of an unconsolidated agricultural material can either be determined experimentally using the porosity tank method or theoretically from bulk and true densities of the material. Porosity can be determined from the difference between bulk volume of a porous material and its volume after destruction of all voids by compression. Porosity determination requires the knowledge of the total or apparent volume, and the void volume included in the material matrix; their difference is also known as the particle volume.

Objective
After performing this experiment you will be able to learn 
Determination of porosity of tin plate.

Introduction

Porosity in tinplate refers to the presence of tiny holes or pores in the tin coating on steel sheets used for making tin cans. These pores can expose the underlying steel to the contents of the can, potentially leading to corrosion and contamination of the food product. Ensuring minimal porosity is crucial for maintaining the integrity and safety of food packaging. Tinplate is produced by coating a thin layer of tin onto a steel sheet. This can be done through hot dipping or electroplating. The goal is to create a uniform and continuous tin layer that acts as a protective barrier against corrosion. During the coating process, imperfections such as pores or pinholes can form in the tin layer. These imperfections can occur due to variations in the coating thickness, impurities in the tin, or mechanical damage during handling and processing.When a tinplate can with porosity is filled with food, the contents can come into direct contact with the exposed steel through the pores.The acidic or basic nature of certain food products can accelerate the corrosion of the exposed steel, leading to the formation of rust.This corrosion can compromise the structural integrity of the can and potentially contaminate the food with rust particles or harmful by-products of the corrosion process. The primary function of the tin coating is to act as a physical barrier that prevents the food from contacting the steel. A continuous and defect-free tin layer ensures effective protection.Tin also provides cathodic protection to the steel. In the presence of an electrolyte (e.g., acidic food), tin acts as the sacrificial anode, corroding preferentially to the steel. However, this mechanism is only effective if the tin layer is relatively thick and the porosity is minimal.

Take 5 ml/2.5 ml aliquot in a 25 ml volumetric flask.

Introduction

In order to use a fine quality of DNA for various molecular biological work like sequencing, cDNA synthesis and cloning, RNA transcription, transfection, nucleic acid labeling (random primer labeling), etc., quality and quantity of DNA is extremely important to have the defined template concentration. Failure to produce results from the above techniques can sometimes be attributed to an incorrect estimate of the DNA template used.

Materials Required

Sample, reagents, beakers, conical flasks, pestle and mortar, funnels, volumetric flasks, pipettes, hot plate, weighing balance, spectrophotometer/colorimeter.

Reagents

    1.    0.1 N NaOH: Dissolve 4 g NaOH (AR) crystals in sufficient water to make up the final volume 1 Litre.
    2.    1 % Phenolphthalein: Dissolve 1 g in 100 ml water. Readymade indicator solutions are more commonly used.
    3.    Alkaline copper Tartarate
        a.    Dissolve 12.5 g anhydrous sodium carbonate, 10 g sodium bicarbonate, 12.5 g potassium sodium tartarate and 100 g anhydrous sodium sulphate in about 400 ml of distilled water and make up the final volume to 500 ml.
        b.    Dissolve 15 g copper sulphate in distilled water. Add one drop of sulphuric acid and make up to 100 ml in distilled water.
    4.    Always prepare fresh Alkaline Copper Tartarate reagent by mixing 96 ml of sol. a. and 4 ml of sol. b. and before use.
    5.     Arsenomolybdate Reagent: Dissolve 5.0 g ammonium molybdate (AR) in 90 ml of distilled water. Add about 5.0 ml of concentrated sulphuric acid and mix well. Add 600 mg of disodium hydrogen arsenate dissolved in 50 ml water. Mix well and incubate the prepared reagent at 37ºC for 24-48 hr or 55ºC for 30  min. with constant stirring.

Materials Required

Ostwald viscometer, stop watch, sample, distilled water, thermometer.

Procedure

    a.    Take sample and distilled water. Record their temperatures (they should be same for correct estimation). If the temperatures are not same bring both to a specific temperature say 20ºC or the room temperature.
    b.    Clean and dry the Ostwald viscometer properly before use
    c.    Fill the ostwald viscometer with distilled water and record the time taken (T₁) for the a known volume of water to flow through the orifice.
    d.    Empty the viscometer and dry it
    e.    Fill the ostwald viscometer with sample juice or liquid and record the time taken (T₂) for the a known volume of sample to flow through the orifice of the same viscometer.
    f.    Calculate the relative viscosity using the following formula

Materials Required

Sensory scoring card, products, pen/ pencil for coding, plain water.

Procedure

    1.    Assign codes to the samples i.e. a, b, c, …… or 1, 2, 3, ….. etc.
    2.    Keep the coded samples randomly (eg. c, f, a, b, d, e) in a row for evaluation
    3.    Start the evaluation of samples one by one. 
    4.    Evaluator should rank the samples on the basis of intensity of a single sensory attribute according to his / her preference.
    5.    Compute the means on the basis of the evaluation of different evaluators (replications).
    6.    List the samples in increasing or decreasing order of preference.

Materials Required

Sensory scoring card, products, pen/pencil for coding, plain water.

Procedure

    1.    Take the given two samples
    2.    Make them three by duplicating/repeating either one of the two
    3.    Assign codes to the samples eg. AAB, ABA, ABB,  BAB etc.
    4.    Ask the evaluators to evaluate the samples for any differences between the 3 on the given Specimen Evaluation Card.
    5.    Find out how many of the evaluators have chosen the odd sample correctly (say it is 16 out of 20 evaluators).
    6.    Now find out the degree of difference in the samples indicated by the evaluators who correctly found the odd sample (Say it is much as per 3, moderate as per 8 and slight as per 5 out of the 16 correct evaluators.).
    7.    Find out how many of the correct evaluators preferred A sample and how many the B sample (say 11 preferred A sample and 5 B sample).
    8.    After going through Annexure II you may conclude that the two samples differed significantly from each other as 16 out of 20 evaluators found the odd sample correct. But, the preference was not significant as it should have been at least 13 out of 16 judges indicating same preference so as to make it significant. So, it may be concluded that the two samples differ significantly but both are acceptable.

Materials Required

Sensory scoring card, products, pen/ pencil for coding, plain water

Procedure

    1.    Assign codes to the samples i.e. a, b, c, …… or 1, 2, 3, ….. etc.
    2.    Keep the coded samples randomly (eg. c, f, a, b, d, e) in a row for evaluation
    3.    Start the evaluation of samples for various sensory attributes one by one. 
    4.    Evaluator should rinse his/ her mouth after each sample so as to avoid overlapping of taste, flavour etc.
    5.    Assign marks from 1-9 based on pleasurable and un pleasurable experiences.
    6.    Compute the means for a particular attribute on the basis of the evaluation of different evaluators (replications).
    7.    Find out the best sample on the basis of highest average scores obtained.

Determination of size of the food materials

Size is an important physical attribute of foods used in screening solids to separate foreign materials, grading of fruits and vegetables, and evaluating the quality of food materials. Various types of cleaning, grading and separation equipment are designed on the basis of size. The size and shape of the grains are used to determine the size of screen openings, angle of inclination, vibration amplitude and frequency of screen in designing an air screen grain cleaner and conveying characteristics of the solid materials.