CHAPTER 9 CORRELATION OF FOOD NUTRIENTS WITH THE DIELECTRIC PROPERTIES OF SOME FOODGRAINS, PULSES AND OILSEEDS

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1 of food nutrients with the dielectric properties CHAPTER 9 CORRELATION OF FOOD NUTRIENTS WITH THE DIELECTRIC PROPERTIES OF SOME FOODGRAINS, PULSES AND OILSEEDS 9.1 Introduction The major constituents of different types of foods are their nutrients viz., proteins, fats, fiber, ash, carbohydrates and moisture contents. The electrical properties of food grains have been found to have relationship with their nutrients and have important applications in the field of agriculture. Dielectric constant (ε') and dielectric loss (ε'') factor are the properties of primary importance for predicting heating rates for food materials when subjected to microwave radiation. Dielectric properties can also be used in assessment of food quality. It has now been established that the dielectric properties of food grains, pulses, and oilseeds mainly depend on their moisture content. The total average values of dielectric properties also depend on the food nutrients, like, proteins, fats, fiber, ash and carbohydrates. Therefore, the detailed study of their dependence on the food nutrients is helpful to develop a better understanding of physical phenomena in agricultural physics and food science, like maturity of fruits, moisture level of crops, cooking and processing of food by microwaves etc. The correlation between the dielectric properties of food grains, pulses and oilseeds with their food nutrients will therefore be beneficial for product and process development and in the modern design of dielectric heating systems for the requirements of intended applications Nutrients Nutrients are the nutritious components in foods that an organism utilizes to survive and grow. Food nutrients are mainly of two types : (a) macro nutrients, viz., fats, carbohydrate etc.(b)micro nutrients, viz., vitamins, iron, calcium, zinc, iodine etc. Macronutrients provide the major portion of energy for an organism's metabolic system to function, while micronutrients provide the necessary cofactors for metabolism to be carried out efficiently. Both types of nutrients can be acquired from the environment (Whitney and Rolfes, 2005). They are used to build and repair

2 of food nutrients with the dielectric properties tissues, regulate body processes, and are converted into energy required by the body to perform different functions. Good nutrition helps preventing diseases and promotes healthy living. There are six categories of essential nutrients that the body requires from food : carbohydrates, fats, fiber, vitamins, minerals and water Proteins Proteins play a crucial role in growth of any living organism. Proteins are important constituents of tissues and cells of the body. The proteins in the form of enzymes and hormones are responsible for a wide range of vital metabolic processes in the body. Proteins, as antibodies help the body to defend against infections. Proteins supply amino acids, which help to build and maintain healthy body tissues. There are as many 20 amino acids, which are considered essential for our healthy living, because their right amount in right proportion is required by the body to function properly. Twelve of these amino acids are produced in the body but the other eight (amino acids) must be provided by the diet. All foods, except the refined sugar, oil and fats contain different amount of proteins Fats Fats are an important component of diet, which support a number of functions in the body. They are the concentrated source of energy that supplies more than twice the energy per unit weight provided by either proteins or carbohydrates. Their presence in the diet is important because they help in absorption of fat soluble vitamins like, vitamin A and carotene present in the diet. Fat is also known as lipid and is mainly present in food in a form called 'triglycerides'. Fats and oils are classified as saturated and unsaturated according to the number and bonding of the carbon atoms in the aliphatic chain. Saturated fats have no double bonds between the carbons in the chain while unsaturated fats have one or more double bonded carbons in the chain. The fats present in the diet are of two kinds : the visible fat and invisible fat Carbohydrates Carbohydrates are a class of energy yielding materials and constitute the major part of our daily intake. Carbohydrates are of two types : simple and complex

3 of food nutrients with the dielectric properties carbohydrates. Complex carbohydrates are preferred as food components as they are more nutritious yet have fewer calories per gram as compared to fats and fewer problems with overeating than those encountered with fats or sugar. Complex carbohydrates are also preferred over simple carbohydrates by diabetic people because their sugar contribution is less harmful Fiber Dietary fiber is a type of carbohydrates that cannot be digested by the body. It is found in edible plant foods, such as cereals, fruits, vegetables, dried peas, nuts, lentils and grains. Though most carbohydrates are broken down into sugar molecules, fiber cannot be broken down into sugar molecules, and instead it passes through the body undigested. Fibers help in regulating use of sugars by the body, helping to keep hunger and blood sugar under check. Fiber appears to reduce the risk of developing various conditions, including heart disease, diabetes, diverticular disease, and constipation. Fibers are grouped into soluble and insoluble on the basis of their physical properties. All types of fiber have important roles to play in human metabolism Moisture Content Moisture content is one of the most important constituenst of food materials A knowledge of the moisture content is often necessary to predict the behaviour of foods during their processing, e.g., mixing, drying and packaging. The texture, taste, appearance and stability of foods depend on the amount of water they contain.. The propensity of microorganisms to grow in foods is dependent on their water content. For this reason many foods are dried below some critical moisture content, for saving them from being spoiled refers to a technique used to measure the relationship between two or more variables. When two quantities are correlated, it means that they vary together. It represents the degree of linear association between such variables. In statistics, the correlation is estimated in terms of the Pearson product-moment correlation coefficient, which measures the linear relationship between two variables

4 of food nutrients with the dielectric properties X and Y and varies between +1 and 1 inclusive; the value 1 showing a total positive correlation, 0 shows no correlation and 1 represents the total negative correlation. does not make a priori assumption as to whether one variable is dependent on the other(s)and it does not prove or disprove any cause-and-effect (causal) relationship between the variables, instead it gives an estimate as to the degree of association between the variables. Thus, correlation is useful in discovering possible connections between variable. In fact, correlation analysis tests for interdependence of the variables. The strength of the relationship is represented by the correlation, but it can actually be measured by the coefficient of determination( r 2 ). The significance of the relationship is expressed in terms of the probability level (p), which tells how unlikely a given correlation coefficient r will occur, given no relationship exists in the population, viz., p = 0.05 indicates significant correlation. The smaller the p-level, the more significant is the relationship; the stronger the relationship, larger is the value of correlation coefficient. The Pearson coefficient is widely used in the sciences to represent the degree of linear dependence between any two variables (Pearson, 1895; Stigler and Stephen, 1989) i Coefficient, (r) The strength and direction of linear relationship between two variables is measured by a quantity r, called the linear correlation coefficient. It is sometimes referred to as the Pearson product moment correlation coefficient, in the honour of its developer Karl Pearson. The value of the correlation lies in the range -1 < r < +1. The + and signs are used to represent the positive linear correlation and negative linear correlation, respectively. It is a dimensionless quantity; i.e., its value does not depend on the units employed i.a Positive For strong positive linear correlation between x and y, r is close to +1. A perfect positive linear fit is indicated by r = +1. A positive value of r indicates that as the value of x increases, the value of y also increases, i.e., the slope of the x y line is positive.

5 of food nutrients with the dielectric properties i.b Negative When r is close to -1, the variables x and y are said to have a strong negative linear correlation. A negative value of r indicates that as the value of x increases, the value of y decreases, i.e., the slope of x y line is negative i.c No When r is close to zero, the variables x and y are said to have no linear correlation or to have a weak linear correlation. A value of r near zero indicates that there can be random non linear relationship between the two variables, but no linear relationship. In case of a perfect correlation (r = ± 1) all the data points lie on the straight line between the two variables. The Pearson correlation coefficient is called symmetric if corr (X, Y) = corr (Y, X) Between Dielectric Properties and Nutrients Since the dielectric properties of foods depend on their chemical composition, it is possible to develop a correlation between dielectric properties of food entities with their nutrients viz., moisture, crude proteins, fats, crude fiber, total ash and total carbohydrates. In the present research we have tried to establish a correlation between the dielectric properties (dielectric constant and loss factor) and the nutrients of some food grains, pulses and oilseeds, and find out the value of correlation for them. The influence of water and salt (or ash) content on dielectric properties depends largely on the manner in which they are bound or restricted in their movement by the other food components (Venkatesh and Raghvan,2004). Tabil (2006) observed that the dielectric properties of food products depend on their composition. Carbohydrates, Fats, Moisture, Proteins and salt contents are the major components of food materials. Many researchers viz., Calay et al.(1995); Guan et al. (2004) ; Sun et al. (1995) have made attempts to express dielectric properties as a function of processing variables and chemical composition. These attempts include modelling a single food item, as well as a combined data of a wide range of food commodities. Sun et al. (1995) compiled the data of dielectric properties available

6 of food nutrients with the dielectric properties in literature and their dependence on moisture, ash contents of fruits, vegetables, fish, and meats to develop predictive equations. They concluded that it was difficult to develop a generic composition based equations for dielectric properties of all food products. Therefore, it was considered desirable to develop such equations for a specific product or a group of products of food. Calay et al. (1995) grouped food materials into grains, meats, vegetables and fruits, and developed the predictive equations for their dielectric properties based on moisture, salt, fats, and temperature with the coefficients of determination (R 2 ) lying between 0.70 to Sipahioglu and Barringer (2003) developed predictive models describing the dielectric properties at 2450 MHz as a function of temperature (5 130 C), ash, and moisture content for 5 fruits and 10 vegetables. However, the dielectric properties of some of the vegetables, such as yam, white potato, and spinach did not fit within the developed equations. The problem was attributed to the transition in the physical properties of the carbohydrate components in these vegetables during heating. Guan et al. (2004) developed such equations for dielectric properties of mashed white potatoes for a range of moisture and salt contents, subjected to pasteurization and sterilization by radio-frequency and microwave processes in the frequency range (1 1800) MHz and temperatures (20 C to 120 C). However, the major constituents in starchy vegetables, such as starch and sugar contents, were not considered in the developed regression equations Regression Analysis Regression analysis is a process of finding out the relationship between a dependent variable and one or more independent variables. A model of the relationship between the variables is hypothesized, and the values of the parameters are used to develop a relationship in the form of regression equation. If the model is proved to be satisfactory, the regression equation can be utilized for predicting the values of the dependent variables, provided that the values of the independent variables are given.

7 of food nutrients with the dielectric properties Materials The food grains used in the present study are: i. Cereals and grains : Wheat, Rice, Barley, Pearl Millet, Sorghum ii. Pulses and legumes : Chickpea, Whole Green gram, Split green gram iii. Nuts and oilseeds : Mustard seeds, Soybean Grains of four different varieties of farm type wheat (viz., LOK 1, UP 2382, RAJ 3765 and RAJ 2384) required for the present studies were obtained from Durgapura Agriculture Research Station of Rajasthan Agriculture University, Bikaner and one sample of local variety of fresh crop (Sharbati) was procured from the market. Also, the samples of Pearl Millet, Chickpea, and Barley grains of different varieties were also obtained from Durgapura Agriculture Research Station. Samples of rice, sorghum and soybean which could not be available from the Durgapura Research station, were purchased from the local market. The samples of mustard seeds were, however, obtained from the National Mustard Research Centre, Sewar, Bharatpur. 9.3 Methodology The dielectric properties of all the above stated food grains were determined in powder form at four microwave frequencies lying in C, J, X and Ku bands of microwaves viz., 4.65 GHz, 7.00 GHz, 9.35 GHz and GHz respectively, by using two point method and employing the dielectric cells specially designed for powders to be used in the microwave benches for the four microwave bands. The experimental details of the two point method have been discussed in Chapter 3. Also, the dielectric properties of wheat determined by this method in powder form for five different varieties (cultivars) at 9.35 GHz for grain size microns have already been reported in Table 8.2 of Chapter 8 of this thesis.the nutrients of all the food grains mentioned above and five varieties of wheat were determined by employing following methods, which are well established in bio chemical sciences and can be used for the analysis of food nutrients.

8 of food nutrients with the dielectric properties Table 9.1: Biochemical methods for estimation of food nutrients S.No. Name of Nutrient Method Reference 1. Proteins Micro Kjheldal Method AOAC, Fats Ether extractive method AOAC, Moisture Oven drying AOAC, Carbohydrates Calculation Method AOAC, Crude fiber Acid Alkali Method AOAC,2005 The details of these standard biochemical methods have been discussed in Chapter 3. between the dielectric properties and nutrients of food materials is then established by using SPSS software. The module of SPSS used was SPSS SPSS is one of the most widely used softwares for statistical analysis in social sciences. 9.4 Results and Discussion The dielectric properties of food grains, viz., barley, rice, sorghum, pearl millet, wheat, chickpea, green gram, split green gram and mustard seeds were determined by two point method at four different frequencies and the results have been discussed in chapter 4. The nutrients of these food grains are determined by standard biochemical methods given in Table 9.1 and the results obtained are displayed in Table 9.2. Table 9.2 : Values of food nutrients for different varieties of food grains, pulses and oilseeds Sample Moisture Proteins Fats Crude Fiber Carbohydrates Barley(RD 2508) 11.69± ± 2.04± ± 66.99±0.59 Rice (PR 11) 12.28± ± ± 0.50± 81.00±0.75 Sorghum (CH5) ± 2.34± ± 70.34±0.79 Pearl Millet (HHB 62) 10.66± ± ± ± ±0.62 Wheat(Raj 2384) 9.39± ± 1.56± ± ±0.78 Chickpea(RSG 888) 9.66± ± ± ± 54.95±0.65 Green gram (Mani) 12.86± ± ± 4.10± ±0.89 Split green gram(mani) 12.51± ± ± 0.80± 59.90±0.85 Mustard Seeds (MAYA) 9.01± ± ± ± 21.50±0.56 Soyabean 12.01± ± ± ± 21.02±0.86

9 of food nutrients with the dielectric properties The nutrient analysis for five different varieties of wheat was also done by employing the methods described in Table 9.1. The results obtained are assembled in Table 9.3. Table 9.3: Values of food nutrients for five varieties of wheat Variety Moisture Proteins Fats Carbohydrates Ash Fiber LOK ± ± ± ± ± ± 0.22 UP ± ± ± ± ± ± 0.14 RAJ ± ± ± ± ± ± RAJ ± ± ± ± ± ± Sharbati 10.20± ± ± ± ± ± of Dielectric Properties of Food Grains, Pulses and Oilseeds with Their Nutrients In order to determine correlation between different nutrients and the electrical properties, i.e., the dielectric constant (ε') and dielectric loss factor (ε'') of different varieties of food grains, pulses and oilseeds, the values of their ε' and ε'' at four different frequencies viz., 4.65 GHz,7.00 GHz, 9.38 GHz and GHz along with their food nutrients are reproduced in Tables 9.4, 9.5, 9.6 and 9.7 respectively. analysis was done using SPSS software and the values of the correlation coefficient r for Barley(RD 2508), Rice (PR 11), Sorghum (CH5 ), Pearl Millet (HHB 62), Wheat (RAJ 2384), Chickpea (RSG 888), Green gram (MANI) Split green gram(mani), Mustard Seeds (MAYA), Soybean are reported in Table 9.8.

10 of food nutrients with the dielectric properties Table 9.4 : Values of Dielectric constant(ε') and dielectric loss factor (ε'') of different varieties of food grains, pulses and oilseeds at 4.65 GHz frequency along with the estimated values of food nutrients Sample ε' ε'' Moisture Proteins Fats Crude Fiber Carbohydrates Barley (RD 2508) 4.55 ± 0.40 ± ± ± 2.04 ± ± ± 0.59 Rice (PR 11) 2.34 ± 0.25 ± ± ± ± 0.50± ± 0.75 Sorghum (CH5) 4.23 ± 0.34 ± 11.46± ± 2.34± ± 70.34± 0.79 Pearl Millet (HHB 62) 4.31 ± ± ± ± ± ± ± 0.62 Wheat (RAJ 2384) 4.28 ± 0.32 ± 9.39 ± ± 1.56 ± ± ± 0.78 Chickpea (RSG 888) 4.52 ± ± 9.66 ± ± ± ± ± 0.65 Green gram (MANI) 4.04 ± ± 12.86± ± ± 4.10 ± ± 0.89 Split green gram (MANI) 3.83 ± ± 12.51± ± ± 0.80 ± ± 0.85 Mustard Seeds (MAYA) 4.88 ± ± 9.01 ± ± ± ± ± 0.56 Soyabean

11 of food nutrients with the dielectric properties Table 9.5 : Values of Dielectric constant(ε') and dielectric loss factor (ε'') of different varieties of food grains, pulses and oilseeds at 7.00 GHz frequency along with the estimated values of food nutrients Sample ε' ε'' Moisture Proteins Fats Crude Fiber Carbohydrates Barley (RD 2508) 3.89 ± 0.35 ± ± ± 2.04 ± ± ± 0.59 Rice (PR 11) 1.91 ± 0.17 ± ± ± ± 0.50 ± ± 0.75 Sorghum (CH5) 3.85 ± ± 11.46± ± 2.34± ± 70.34± 0.79 Pearl Millet (HHB 62) 4.03 ± ± 10.66± ± ± ± ± 0.62 Wheat (RAJ 2384) 3.97 ± ± 9.39 ± ± 1.56 ± ± ± 0.78 Chickpea (RSG 888) 3.57 ± ± 9.66 ± ± ± ± 54.95± 0.65 Green gram (MANI) 2.87 ± ± 12.86± ± ± 4.10 ± ± 0.89 Split green gram (MANI) 2.30 ± 0.25 ± 12.51± ± ± 0.80 ± 59.90± 0.85 Mustard Seeds (MAYA) 3.97 ± 0.31 ± 9.01 ± ± ± ± 21.50± 0.56 Soyabean

12 of food nutrients with the dielectric properties Table 9.6 : Values of Dielectric constant (ε') and dielectric loss factor (ε'') of different varieties of food grains, pulses and oilseeds at 9.35 GHz frequency along with the estimated values of food nutrients Sample ε' ε'' Moisture Proteins Fats Crude Fiber Carbohydrates Barley (RD 2508) 2.28 ± 0.28 ± 11.69± ± 2.04± ± 66.99± 0.59 Rice (PR 11) 1.60 ± ± 12.28± ± ± 0.50± 81.00± 0.75 Sorghum (CH5) 3.16 ± 0.24 ± 11.46± ± 2.34± ± 70.34± 0.79 Pearl Millet (HHB 62) 3.03 ± ± 10.66± ± ± ± ± 0.62 Wheat (RAJ 2384) 3.63± 0.15 ± 9.39± ± 1.56± ± ± 0.78 Chickpea (RSG 888) 2.78 ± 0.29 ± 9.66± ± ± ± 54.95± 0.65 Green gram (MANI) 2.50 ± 0.26 ± 12.86± ± ± 4.10± ± 0.89 Split green gram (MANI) 2.05 ± ± 12.51± ± ± 0.80± 59.90± 0.85 Mustard Seeds (MAYA) 2.31 ± 0.22 ± 9.01± ± ± ± 21.50± 0.56 Soyabean

13 of food nutrients with the dielectric properties Table 9.7 : Values of Dielectric constant(ε') and dielectric loss factor (ε'') of different varieties of food grains, pulses and oilseeds at GHz frequency along with the estimated values of food nutrients Sample ε' ε'' Moisture Proteins Fats Crude Fiber Carbohydrates Barley (RD 2508) 1.86 ± ± ± ± 2.04 ± ± ± 0.59 Rice (PR 11) 1.39 ± ± ± ± ± 0.50 ± ± 0.75 Sorghum (CH5) 2.68 ± 0.16 ± ± 2.34± ± 70.34± 0.79 Pearl Millet (HHB 62) 2.48 ± 0.03 ± ± ± ± ± ± 0.62 Wheat (RAJ 2384) 1.37 ± ± ± ± 1.56 ± ± ± 0.78 Chickpea (RSG 888) 1.97 ± 0.10 ± ± ± ± ± ± 0.65 Green gram (MANI) 1.99 ± ± ± ± ± 4.10 ± ± 0.89 Split green gram (MANI) 1.78 ± ± ± ± ± 0.80 ± ± 0.85 Mustard Seeds (MAYA) 1.35 ± 0.05 ± ± ± ± ± ± 0.56 Soyabean

14 of food nutrients with the dielectric properties Table 9.8: Results of Analysis of dielectric properties of all the food grains (viz., cereals, pulses and oilseeds taken together) with their food nutrients at room temperature (28 C) Moisture protein Fat Fiber Carbohydrate Dielectric constant -ε' (4.65 GHz) Dielectric constant - ε' (7.00 GHz) Dielectric constant - ε' (9.35 GHz) Dielectric constant - ε' (14.98 GHz) Dielectric loss factor-ε'' (4.65 GHz) Dielectric loss factor- ε'' (7.00 GHz) Dielectric loss factor-ε'' (9.35 GHz) Dielectric loss factor- ε'' (14.98 GHz) Significance(p) Significance(p) Significance(p) Significance(p) Significance(p) Significance(p) Significance(p) Significance(p) *. is significant at the 0.05 level (2-tailed)

15 of food nutrients with the dielectric properties It is clear from Table 9.8 that the value of p is more than 0.05 for all values of r. This shows that no significant correlation is obtained between dielectric constant (ε') and the nutrients, i.e., moisture content, proteins, fats, fiber and carbohydrates at any of the four frequencies. Similarly, no significant correlation is obtained between dielectric loss factor (ε'') and the food nutrients. It is apparent from this table that the correlation of dielectric constant with moisture is positive at frequency GHz, whereas it is negative at the other three frequencies. On the other hand, the correlation between dielectric constant and proteins is positive at 4.65 GHz frequency while it is negative for the rest three frequenciesof observation. Similarly,the fats and carbohydrates show positive as well as negative correlation at different frequencies, however the correlation of dielectric constant with fiber is positive at all frequencies. Thus, no particular trend is observed for variation of dielectric constant (ε') with moisture, proteins, fats, fiber and carbohydrates. Dielectric loss factor (ε'') also has positive correlation with fiber and negative correlation with proteins at all the frequencies, but with other nutrients such as moisture, fats and carbohydrates, it has positive correlation at some frequencies and negative at the others. This shows that there is no definite relationship between dielectric loss and nutrients. It may be inferred that contribution of different nutrients to dielectric properties very much depends on the frequency of microwaves. Moreover, the molecules of different nutrients not only behave differently at a particular frequency, but their response to electromagnetic radiation also changes with the frequency of Dielectric Properties of Cereals with Their Nutrients Though no significant correlation between two types of properties and nutrients was obtained when all the three types of food grains (viz., cereals, pulses and oilseeds) were considered together, however, when the correlation analysis was done for dielectric properties and nutrients of one type of materials, say five cereals viz., barley, sorghum, pearl millet, wheat and rice. It was observed that the dielectric constant (ε') and dielectric loss factor (ε'') show significant relationship with several food nutrients, as shown in the table given below. This reveals that for a particular group of food grains the two types of properties show better correlation.

16 of food nutrients with the dielectric properties Table 9.9: coefficients of dielectric parameters (ε' and ε'') of cereals with their nutrients Moisture Proteins Fats Crude Fiber Carbohydrates Dielectric constant -ε' (4.65 GHz) Dielectric constant - ε' (7.00 GHz) Dielectric constant - ε' (9.35 GHz) Dielectric constant -ε' (14.98 GHz) Dielectric loss factor - ε'' (4.65 GHz) Dielectric loss factor- ε'' (7.00 GHz) Dielectric loss factor- ε'' (9.35 GHz) Dielectric loss factor - ε'' (14.98 GHz) Significance (p) Significance(p) * Significance(p) Significance(p) ** Significance(p) ** Significance(p) * * Significance(p) Significance(p) *. is significant at the 0.05 level (2-tailed) **. is significant at the level (2-tailed)

17 of food nutrients with the dielectric properties Results of correlation analysis on five cereals viz. Barley, pearl millet, sorghum, rice and wheat are tabulated in Table 9.9. From this table, it is apparent that at 9.35 GHz frequency the dielectric constant (ε') is significantly correlated with proteins at 5% level of significance, as apparent from the value of significance parameter p = 2. Nutrients like fats, fiber and proteins show positive correlation with ε' at all the four frequencies while carbohydrates show negative correlation with ε' at all the four frequencies, whereas with moisture the correlation is positive at GHz and negative at the other three frequencies. The correlation between dielectric constant and nutrients at a particular frequency can be pictorially depicted by a regression line for the cases where correlation is found to be significant Predictive equations can also be obtained for such a linear relationship by using SPSS-22 package. Fig 9.1 depicts the linear dependence of dielectric constant(ε') of cereals on percentage proteins for the cereals. From Table 9.9, it is also seen that the dielectric loss factor (ε'') shows significant positive correlation with fats at 4.65 GHz, 7.00 GHz and 9.35 GHz, the level of significance being 1% at frequencies 4.65 GHz and 7.00 GHz, whereas the level of significance is 5% at 9.35 GHz. However, at GHz the correlation of ε'' with fats is negative. For dielectric loss (ε''), carbohydrates show negative correlation at all the frequencies, the correlation being significant at 9.35 GHz frequency. For cereals, the dielectric loss factor (ε'') is positively correlated with fiber content at all the four frequencies. However, the moisture and proteins are found to positively correlate with ε'' at some frequencies, the correlation being negative at other frequencies. Graphical representation of linear regression for significant correlations mentioned above is represented in Figs. 9.1 to 9.5

18 Dielectric constant (ε') of food nutrients with the dielectric properties Dielectric constant (ε') - % proteins correlation at 9.35 GHz % Proteins Fig. 9.1: Regression line between dielectric constant (ε') and percentage protein for cereals at 9.35 GHz. From Fig. 9.1, it is clear that dielectric constant (ε') of cereals can be represented by a linear function of % proteins (P) at frequency 9.35 GHz, the equation for this linear regression is given by ε' = 0.323*P (9.1) Equation (9.1) shows that ε' is positively correlated with proteins, the slope of the regression line being The value of both the correlation coefficient (r=0.953) and the significance coefficient (p = 2) between ε' and % proteins show that the significance for this correlation is within 5% level of significance. The dielectric loss factor (ε'') shows significant correlation with fat (F) at frequency 4.65 GHz, 7.00 GHz and 9.35 GHz. Fig. 9.2 depicts the linear regression curve estimation for ε''- fats correlation at 4.65 GHz and the equation of the line in this case is given by ε'' = 3*F (9.2) In this case the correlation coefficient is r = and the significance is The correlation is significant at 1 % level of significance.

19 Dielectric loss factor(ε'') Dielectric loss factor( ε'') of food nutrients with the dielectric properties Dielectric loss(ε'') - % Fats correlation at 4.65 GHz % Fats Fig. 9.2 : Regression line between dielectric loss factor (ε'') and percentage fats for cereals at 4.65 GHz Dielectric loss ( '') - % Fats correlation at 7.00 GHz % Fats Fig. 9.3: Regression line between dielectric loss factor (ε'') and percentage fats for cereals at GHz. In Fig. 9.3, we plot the linear regression line for ε''- fats correlations at 7.00 GHz frequency. It is observed from Fig. 9.4 that dielectric loss factor (ε'') of cereals can be represented by a linear equation with fat (F) at frequency 7.00 GHz, which is given by ε'' = 9*F (9.3)

20 Dielectric loss factor (ε'') Dielectric loss factor (ε'') of food nutrients with the dielectric properties Equation (9.3) shows that the correlation is positive in this case and the value of correlation coefficient is r = 0.960, whereas the significance is p = The correlation is achieved within 5% level of significance in this case. Dielectric loss ( '') - % Fats correlation at 9.35 Ghz % Fats Fig. 9.4: Regression line between dielectric loss factor (ε'') and percentage fats for cereals at 9.35 GHz Fig. 9.4 represents dielectric loss factor (ε'') as a linear function of percentage fat (F) at frequency 9.35 GHz, the equation of which is given by ε'' = 0.060*F (9.4) Equation (9.4) shows that ε'' is positively correlated with % fats, the slope of the line being The correlation is significant in this case within 5%, the correlation coefficient being r = and the significance coefficient is p = Dielectric loss (ε'')-% Carbohydrates correlation at 9.35 GHz % Carbohydrates Fig. 9.5: Regression line between dielectric loss factor (ε'') and percentage carbohydrate for cereals at 9.35 GHz

21 of food nutrients with the dielectric properties As shown in Fig. 9.5, the dielectric loss factor (ε'') is significantly correlated with percentage carbohydrates (C) at frequency 9.35 GHz. The correlation obtained is negative in this case. The linear regression equation is represented by ε'' = -6 * C (9.5) showing that the slope of line is -6.The correlation is significant within 10%, the correlation coefficient being r = and the significance is p= of Dielectric Properties of Pulses with Their Nutrients analysis was done on dielectric properties and nutrients of pulses viz., chickpea, whole green gram, split green gram following the same procedure as discussed above, and the results obtained are compiled in Table Table 9.10: Results of analysis of dielectric properties of pulses and their nutrients Dielectric constant- ε' (4.65 GHz) Dielectric constant- ε' (7.00 GHz) Dielectric constant - ε' (9.35 GHz) Dielectric constant - ε' (14.98 GHz) Moisture Proteins Fats Fiber Carbohydrates Significance Significance * * Significance Significance Dielectric loss factor- ε'' (4.65 GHz) Significance Dielectric loss factor- ε'' (7.00 GHz) Significance Dielectric loss factor- ε'' * (9.35 GHz) Significance Dielectric loss factor- ε'' (14.98 GHz) Significance * is significant at the 0.05 level (2-tailed) ** is significant at the level (2-tailed)

22 Dielectric constant (ε') of food nutrients with the dielectric properties It is observed that dielectric constant (ε') of pulses show significant correlation with fiber and carbohydrate at 5 % level of significance at 9.35 GHz frequency. Dielectric loss factor (ε'') shows negative significant correlation with carbohydrates at 9.35 GHz frequency at significance level of 5%. The ε' shows positive correlation with proteins and fats at all the four frequencies while it shows negative correlation with the % moisture content. Further,it may be observed from this table that correlation for ε'' is positive at all the four frequencies for proteins and fats, and negative for the moisture whereas for fiber and carbohydrates it is positive at some frequencies and negative at the others Dielectric constant(ε') - % fiber correlation at 9.35 GHz Percentage fiber Fig. 9.6 Regression line between dielectric constant (ε') and percentage fiber for pulses at 9.35 GHz From Fig. 9.6, it is clear that at frequency 9.35 GHz, the dielectric constant (ε') of pulses can be represented by a linear function of % fiber (Fib), the equation of the line is given by ε' = *Fib (9.6) Equation (9.6) shows that ε' is positively correlated with % fibers, the slope of the regression line being The values of both the correlation coefficient (r = 0.999) and the significance coefficient (p = 2) between ε' and % fibers are significant within a level of 5% significance.

23 Dielectric loss factor(ε'') Dielectric constant(ε') of food nutrients with the dielectric properties Dielectric constant(ε')- %carbohydrate correlation at 9.35 GHz Fig. 9.7: Regression line between dielectric constant (ε') and percentage carbohydrates for pulses at 9.35 GHz As shown in Fig. 9.7, the dielectric constant (ε') is significantly correlated with percentage carbohydrates (C) at frequency 9.35 GHz.The correlation obtained is negative in this case. The linear equation is represented by ε' = *C (9.7) showing that the slope of line is The correlation is significant within 5%, the correlation coefficient being r = and the significance is p= Fig. 9.8 Regression line between dielectric loss factor (ε'') and percentage carbohydrates for pulses at 9.35 GHz Percentage Carbohydrates Dielectric loss (ε'') - %carbohydrate correlation at 9.35 GHz Percentage Carbohydrates

24 of food nutrients with the dielectric properties Fig. 9.8 represents dielectric loss factor (ε'') as a linear function of % carbohydrates (C) at frequency 9.35 GHz, the equation of which is given by ε'' = - 8*C (9.8) Equation (9.5) shows that ε'' is negatively correlated with % carbohydrates, the slope of the line being -8. The correlation is significant in this case within 5%, the correlation coefficient being r = and the significance coefficient is p= of Dielectric Properties of Wheat with Its Nutrients The values of dielectric constant (ε') and dielectric loss factor (ε'') for five varieties (viz., LOK 1, UP 2382, RAJ 3765, RAJ 2384 and Sharbati) of wheat powder of grain size μm at 9.42 GHz frequency as obtained by two point method are presented in Table This table also contains the values of their food nutrients as obtained from proximate analysis. Table 9.11 : Values of nutrients of five varieties of wheat obtained from proximate analysis and values of their dielectric constant (ε') and dielectric loss factor (ε'') at 9.42 GHz frequency for grain size μm Variety ε' ε'' Moisture Protein Fat Carbohydrate Ash Fiber LOK ± ± ± ± ± ± 0.22 UP ± ± ± ± ± ± 0.14 RAJ ± ± ± ± ± ± RAJ ± ± ± ± ± ± Sharbati ± ± ± ± ± ± 0.21

25 Dielectric constant (ε') of food nutrients with the dielectric properties Table 9.12: coefficients for dielectric parameters (ε' and ε'') of wheat in powder form with grain size μm with food nutrients at 9.42 GHz Moisture Proteins Fats Carbohydrates Ash Fiber Dielectric constant - ε' Dielectric loss factor-ε'' ** Significance(p) * Significance(p) * is significant at the 0.05 level (2-tailed) ** is significant at the level (2-tailed) The correlation coefficients for dielectric parameters (ε' and ε'') of wheat with its nutrients for grain size microns determined by using SPSS software are shown in table Dielectric constant (ε') for grain size microns also has significant relation with moisture with r = at 5 % level of significance. The dielectric loss factor has significant relation with fat at 5% level of significance. Graphical representation of significant correlations are depicted in Fig. 9. to Fig. 9.7 for grain size μm Dielectric constant - % Moisture correlation for wheat at 9.42 GHz % Moisture Fig. 9.9: Regression line between dielectric constant (ε') and percentage moisture content for grain size μm of wheat at 9.42 GHz

26 Dielectric loss factor(ε'') of food nutrients with the dielectric properties In Fig. 9.9, correlation of dielectric constant (ε') of wheat powder for grain size μm has been depicted with % moisture content at 9.42 GHz. The relationship is linear, which can be represented by a linear equation given by ε' = *M (9.8) Equation (9.8) shows that ε' is positively correlated with percent moisture content. The correlation coefficient in this case is r = and the significance parameter is p = 0.005, the level of significance being within 1%. Dielectric loss - % fats correlation at 9.42 GHz % Fats Fig. 9.10: Regression line between dielectric loss factor (ε'') and percentage fat for wheat powder of grain size μm at 9.42 GHz Fig shows the correlation between dielectric loss factor and percentage fat content in wheat powder for grain size 250 μm -300 μm. The figure show a positive correlation. This means that as the fat increases, ε'' also increases. The equation of regression is given by ε'' = 9 *F (9.9) Thus, it is clear from above discussion that no regular trends for correlation are observed in between the nutrients and dielectric properties of wheat at the frequencies of experiment. It is difficult to form, therefore, predictive equations for ε' and ε'' in terms of nutrients. The complex structure of grain kernels (changing with

27 of food nutrients with the dielectric properties stage of maturity and storage), the dependence of the dielectric properties upon moisture content, grain density and temperature, and the unknown character of the dielectric relaxations, all contribute to the complexity of the dielectric behaviour of grains. Granular and powdery materials are so complex in their composition and in their dielectric behaviour that it is usually necessary to measure the electrical properties under the particular conditions of interest to obtain reliable data as has also been observed by Hlavacova, (2005). 9.5 Conclusion The dielectric properties of food grains do not show any significant correlation with food nutrients when food grains of different types, such as cereals, pulses and oilseeds are considered together. However, when we consider the cereal group or pulses group individually, significant correlations with certain nutrients at particular frequencies. Similarly, for wheat, significant correlation was obtained for ε' and ε'' with only a few nutrients. Therefore, it can be concluded that Dielectric properties of a typical food material depend on a number of factors and cannot be easily predicted just based on its proximate analysis and composition. The reasons which make the composition based predictions of dielectric properties of foods so difficult are that the molecular structures and chemical compositions of the nutrients are quite complex and susceptible to different physical conditions, whose effects differ for different nutrients and that both non electrolyte and electrolyte systems play an important role in determining the dielectric properties of foods.