Physical Properties of Agricultural and Biological Materials PDF

I. PHYSICAL PROPERTIES Learning Objectives: At the end of this lesson, the students should be able to: 1. Understand the importance of knowing the physical properties of agricultural and biological materials 2. Differentiate physical properties of agricultural and biological materials...

I. PHYSICAL PROPERTIES Learning Objectives: At the end of this lesson, the students should be able to: 1. Understand the importance of knowing the physical properties of agricultural and biological materials 2. Differentiate physical properties of agricultural and biological materials 3. Differentiate the methods in determining the physical properties of agricultural and biological materials Physical characteristics 4. Volume and density (specific = concerned with the physical gravity and porosity) dimensions of a biological or 5. Surface Area agricultural material, such as how much it weighs and how much space 1. Angle of repose, ør it occupies = it includes size, shape, volume, = slope of the sides of the mass of grain when poured to rest by density and surface area of an object gravity on a flat surface = dependent on grain moisture Knowledge of the various physical content and foreign matter properties of biological materials is = useful in designing equipment for essential in guiding the development solid flow and storage structures of: ◘ processing technologies for pest control, disease control, and 2. Angle of friction, øf value-adding; ◘ machinery, facilities and handling = maximum angle at which the systems; and grain remains in equilibrium on ◘ quality evaluation techniques an inclined surface ◘ calculation of the heat transfer = dependent on grain moisture and mass diffusion rates content and type of surface = useful in designing equipment for Physical properties to be considered: transports (load and unload) of 1. Angle of Repose goods and storage bins or 2. Angle of Friction facilities 3. Size and shape = inclination of hoppers: øf + 10° projected area method, electronic inspection systems 3. Size and shape = these are required to describe an object satisfactorily 3.1. Size = can be determined by graphical produce can be sized according to methods, dimensional measurement, different physical parameters, such Strictly for PERSONAL USE ONLY. Do not reproduce. ABE 56 First Semester AY2024-2025  as diameter, length, weight, volume, The dimensions can be measured circumference, projected area, or any using a micrometer or caliper grain combination of these. shape tester. used in screening solids to separate The micrometer is a simple foreign materials, grading of fruits instrument used to measure and vegetables, and evaluating the distances between surfaces. quality of food materials in fluid flow, and heat and mass 3.1.3. Electronic system Various electronic systems are transfer calculations, it is necessary employed to sort agro- commodities to know the size of the sample; it also through off-line or on-line inspection. affects the viscosity and dispersibility This saves labor cost and eliminates and stability of the product human error 3.1. Size (methods of measurement) 3.1.1. Projected area method 3.2. Shape = In this method, three characteristic = describes the object in terms of a dimensions are defined: geometrical body a. Major diameter, which is the = also important in heat and mass transfer calculations, screening solids longest dimension of the to separate foreign materials, grading maximum projected area of fruits and vegetables, and b. Intermediate diameter, which is evaluating the quality of food the minimum diameter of the materials maximum projected area or the = usually expressed in terms of its maximum diameter of the sphericity, aspect ratio, ellipsoid ratio minimum projected area. and slenderness ratio c. Minor diameter, which is the shortest dimension of the 3.2.1. Chartered standards minimum projected area. = In this method, tracings of = Length, width, and thickness terms longitudinal and lateral cross sections are commonly used that correspond of the material can be compared with to major, intermediate, and minor the shapes listed on a charted diameters, respectively standard = Using standard charts, the shape of 3.1.2. Micrometer measurement the product can be defined either by method a number on the chart or by descriptive terms Chartered standards for the shape of apples, peaches and potatoes: Strictly for PERSONAL USE ONLY. Do not reproduce. ABE 56 First Semester AY2024-2025 Descriptive Terms 7. Obovate – inverted ovate 1. Round – approaching spheroid 8. Elliptical – approaching ellipsoid 2. Oblate – flattened at the stem 9. Truncate – having both ends end and apex squared or flattened 3. Oblong – vertical diameter 10. Unequal – one-half larger than greater than the horizontal the other diameter 11. Ribbed – in cross section, sides 4. Conic – tapered toward the apex are more or less angular 5. Ovate – egg-shaped and broad 12. Regular – horizontal section at the stem end approaches a circle 6. Oblique (lopsided) – slanted 13. Irregular – horizontal cross axis connecting stem and apex section departs materially from a circle 3.2.2. Roundness = It is the measure of the sharpness of the corners of the solids (Curry, 1951) 𝐴! ∑ 𝑟 𝑅𝑜𝑢𝑛𝑑𝑛𝑒𝑠𝑠 = = 𝐴" 𝑁𝑅 where: 𝐴! = largest projected area of object in natural rest position 𝐴" = area of smallest circumscribing circle 𝑟 = radius of curvature 𝑅 = radius of maximum inscribed circle 𝑁 = total number of corners summed in numerator Strictly for PERSONAL USE ONLY. Do not reproduce. ABE 56 First Semester AY2024-2025 3.2.3. Sphericity = measure of how closely the shape where: of an object approaches that of a 𝑑# = diameter of largest inscribed mathematically perfect sphere circle 𝑆𝑝ℎ𝑒𝑟𝑖𝑐𝑖𝑡𝑦 𝑑" = diameter of smallest !#" 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑠𝑜𝑙𝑖𝑑 circumscribed circle =+ 6 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑐𝑖𝑟𝑐𝑢𝑚𝑠𝑐𝑟𝑖𝑏𝑒𝑑 𝑠𝑝ℎ𝑒𝑟𝑒 !# 8𝜋;6 =+ $6 bodies 8 ;6450 + D 𝑥 (0.1524𝑚 𝑥 0.1524𝑚 𝑥 0.01𝑚) samples may be determined by solid 𝑚 or liquid displacement methods = 𝟏𝟎𝟒. 𝟓𝟐𝒈 Strictly for PERSONAL USE ONLY. Do not reproduce. ABE 56 First Semester AY2024-2025 4.2.2. Density (measurement) air and liquid. The apparent density 4.2.2.1. bulk density can be calculated from the equation: = can be determined by stacking or 𝑚..,#0 placing a known mass of particles 𝜌, = 𝜌- 𝑥 into a container of known volume, 𝑚..1#2 such as a measuring cylinder where: = material can be filled into a specific 𝑚..,#0 = mass of sample in air geometric container of known 𝜌- = density of the liquid volume, and the excess amount on 𝑚..1#2 = mass of sample in the top of the cylinder can be liquid removed by sliding a string or ruler = based on the Archimedes’ principle: along the top edge of the cylinder “When a body is immersed fully = this method considers all pores inside or partially in a fluid, it as well as outside the individual experiences an upward force particles that is equal to the weight of fluid = after the excess has been removed, displaced by it” the mass of the sample can be measured, and the bulk density can be estimated as: 𝑚 𝜌* = 𝑉* 4.2.2.2. particle density = can be measured by the volume displacement method used in apparent density measurement without coating the particle or object 4.2.2.3. apparent density 4.2.2.3.3. liquid displacement 4.2.2.3.1. geometric dimension method method by direct measurement of volume of The apparent density of a shape of liquid displaced regular geometry can be determined difference between the initial volume from the volume calculated from the of the liquid in a measuring cylinder characteristic dimensions and mass and the volume of the liquid plus this method is not suitable for soft immersed material (coated) is the and irregularly shaped mate-rials, volume of the material where it is not easy to measure the characteristic dimensions (Rahman, The use of a specific gravity bottle 1995) and toluene has been practiced for many years (Bailey, 1912) A small-neck specific gravity bottle is 4.2.2.3.2. buoyant force method not suitable for large objects; thus, a = In this procedure, buoyant force can special design is required. be determined from sample weight in The volume of a specific gravity bottle can be measured using distilled water Strictly for PERSONAL USE ONLY. Do not reproduce. ABE 56 First Semester AY2024-2025  Toluene has many advantages when used as reference liquid Sample problem #2 1. Little tendency to soak on the An avocado was weighed on sample an electronic balance and then 2. Smooth flow over the surface suspended in a beaker of water. The due to surface tension weight of the avocado was 219.8 3. Low solvent action on grams. The container filled with constituents, especially fats water weighed 1137.1 g and when and oils the avocado was suspended in the 4. Fairly high boiling point container, the beaker, water and 5. Stable specific gravity and avocado weighed 1355.3 g. Water viscosity when exposed to the temperature was 20°C (ρw=0.9982 atmosphere g/cc). Determine the density of the 6. Low specific gravity avocado. Toluene is carcinogenic; thus, Given: adequate precautions need to be mavo = 219.8 g taken in using it mcontainer+water = 1137.1 g mcontainer+water+avo = 1355.3 g 4.2.2.3.4. solid displacement Reqd: 𝜌,34 method Soln: = the apparent By Archimedes’ principle volume of an 𝑉,34 = 𝑉5#.!1,"65 -,860 irregular solid 𝑚5#.!1,"65 -,860 can be measured 𝑉5#.!1,"65 -,860 = 𝜌-,860@%:°< by a solid 1355.3𝑔 − 1137.1𝑔 displacement of = 0.9982 𝑔/𝑐𝑚+ glass bead = 218.59𝑐𝑚+ displacement 𝑚,34 219.8𝑔 method 𝜌,34 = = = glass beads have Figure 1-1. Sample + glass 𝑉,34 218.59𝑔 beads (Joardder, et al., 2015) an advantage over sand due to their = 𝟏. 𝟎𝟏 𝒈/𝒄𝒎𝟑 uniform size and shape, thus producing reproducible result Strictly for PERSONAL USE ONLY. Do not reproduce. ABE 56 First Semester AY2024-2025 4.3. Specific gravity = ratio between the density of an object, and a reference substance = can tell us, based on its value, if the object will sink or float in our reference substance = usually our reference substance is water which has a density of 1 gram per milliliter or 1 gram per cubic centimeter. = ' Sample problem #3 >% ? @ ∀ % A BA Determine the volume measurement 𝑆𝐺8 = >& = ' = A )*% BA) = ? @ )*& ) ∀ & for a sample of 16 corn kernels (DE.%+FFGBHH.IJIEG) coated with Pliabond using the (E$.DD:FGBHH.IJIEG) = 0.8648 pycnometer method: 𝑐𝑜𝑛𝑠𝑖𝑑𝑒𝑟𝑖𝑛𝑔 𝜌- = 1𝑔/𝑐𝑐, Weight of sample = ∴ 𝜌8 = 0.8648𝑔/𝑐𝑐 4.598g 𝜌.,A!16 = A A+ L>% = Weight of pycnometer %.-.+)/012- A + L >% = 55.6468g MA)*% NA+ OBA)*%*+ Weight of pycnometer & toluene = 78.2399g 𝜌.,A!16 Weight of pycnometer & water = (4.598𝑔)(0.8648𝑔/𝑐𝑐) = 81.7709g [(78.2399𝑔 + 4.598𝑔) − 79.6226𝑔] Weight of pycnometer plus toluene & (4.598𝑔)(0.8648𝑔/𝑐𝑐) 𝜌.,A!16 = sample = 79.6226g 3.2153 Reqd.: Volume = 1.2367𝑔/𝑐𝑐 𝑚. (4.598𝑔) ∀.,A!16 = = Soln.: 𝜌. 1.2367𝑔/𝑐𝑐 = 𝟑. 𝟕𝟐𝒄𝒄 4.4. Porosity 𝜀* 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑣𝑜𝑖𝑑𝑠 𝑜𝑢𝑡𝑠𝑖𝑑𝑒 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 P 𝑠 𝑏𝑜𝑢𝑛𝑑𝑎𝑟𝑦 = indicates the volume fraction of void = space or air in a material and is 𝑡𝑜𝑡𝑎𝑙 𝑣𝑜𝑙𝑢𝑚𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑠𝑡𝑎𝑐𝑘𝑒𝑑 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙𝑠 𝝆𝒃 defined as 𝜺𝒃 = 𝟏 − 𝝆𝒂 𝑎𝑖𝑟 𝑜𝑟 𝑣𝑜𝑖𝑑 𝑣𝑜𝑙𝑢𝑚𝑒 𝜀= 𝑡𝑜𝑡𝑎𝑙 𝑣𝑜𝑙𝑢𝑚𝑒 4.4. Porosity (uses) = different forms of porosity are used in 4.4.1. In reservoir or land & water food process calculations and food engineering products characterization = Porosity is a measure of the volume within a rock that is available to 4.4.1. bulk porosity, 𝜺𝒃 contain reservoir fluids = volume of fraction of voids outside the boundary of individual materials when packed or stacked as bulk: Strictly for PERSONAL USE ONLY. Do not reproduce. ABE 56 First Semester AY2024-2025 4.4.2. In food or crop processing & heat transfer studies in heating and machinery cooling processes Heat and mass transfer in solids depend on density and porosity 5.1. Surface area (types) values 5.1.1. Boundary surface area Textural and sensorial properties of = mainly estimated from geometric foods are also related to density and dimensions or measured by image analysis or contour analysis. porosity Porosity is related to the chemical 5.1.2. Pore surface area stability of dried products, = surface of the pores in a porous degradation of sugars and lipid medium exposed to fluid flow either oxidation per unit volume or per unit mass of the solid particles. 5. Surface Area 5.1.3 Cross-sectional area = area of a surface after longitudinal or = The outside part or uppermost layer trans-verse section of a material of something = necessary when fluid is flowing over = Important in investigations related to an object spray coverage, removal of spray = methods of boundary surface area residues, respiration rate, light can also be used reflectance and color evaluation, and Strictly for PERSONAL USE ONLY. Do not reproduce. ABE 56 First Semester AY2024-2025 Learning Objectives: Other agricultural materials have At the end of this lesson, the more complicated shapes and can be students should be able to: approximated with a combination of 1. Define surface area solids 2. Differentiate the different types of surface area a. Fruit surface area (prolate 3. Differentiate methods of spheroid) measurement of surface area of 2𝜋𝑎𝑏 agricultural materials 𝑆𝐴 = 2𝜋𝑏 % + 𝑠𝑖𝑛B$ 𝑒 𝑒 𝑏 % e 𝑒 = 1−> D 5. Surface Area 𝑎 = The outside part or uppermost b. Fruit surface area (oblate layer of something spheroid) = Important in investigations 𝑏% 1 + 𝑒 related to spray coverage, 𝑆𝐴 = 2𝜋𝑎% + 𝜋 𝑙𝑛 removal of spray residues, 𝑒 1−𝑒 respiration rate, light reflectance 𝑏 % and color evaluation, and heat 𝑒 = e1 − > D 𝑎 transfer studies in heating and cooling processes where: 𝑎 = major semi-axis of the ellipse of 5.1. Surface area (types) rotation or radius on the major axis 5.1.1. Boundary surface area 𝑏 = minor semi-axis of the ellipse of = mainly estimated from rotation or radius on the minor axis geometric dimensions or 𝑒 = eccentricity measured by image analysis or contour analysis. b. Fruit surface area (frustum right 5.1.2. Pore surface area cone) = surface of the pores in a 𝑆𝐴 = 𝜋(𝑟$ + 𝑟% )fℎ% + (𝑟$ − 𝑟% )% porous medium exposed to fluid where: flow either per unit volume or per ℎ = altitude unit mass of the solid particles. 𝑟$ = radius of top 5.1.3 Cross-sectional area 𝑟% = radius of base = area of a surface after 5.2.2. Egg surface area longitudinal or trans-verse section of a material a. Empirical equation of surface = necessary when fluid is area flowing over an object Weigh the egg samples using an = methods of boundary surface electronic balance. The surface area area can also be used of the egg will be computed using the 5.2. Surface area (methods of empirical equation reported by Besch measurement) et al. (1968). The formula of the 5.2.1. Fruit surface area surface area is given by the equation: Similar with volume, agricultural 𝑆𝐴 = 𝑘𝑊 A products can be estimated using where: similarity to geometric solids SA = Surface area, cm2 Strictly for PERSONAL USE ONLY. Do not reproduce. ABE 56 First Semester AY2024-2025  W = weight of egg, g ∆𝑦 = interval of the segments or the k= constant, 4.56-5.07 height of the cylinder m= constant, 0.66 𝑑# = diameter or length of the b. Summation of SA using segment projected method To estimate the SA of a fresh egg, c. Resemblance to a prolate the profile of the egg is determine spheroid using overhead projector (OHP). Use The major and minor diameters of the a transparent ruler to be projected in sample chicken egg will be measured OHP and the projected length of an using the digital caliper. The values inch will be measured. Then the will be recorded, and the surface area profile will be divided into upper will be computed using the formula: segment, lower segment and the 𝑑 𝐷 % middle sections of Δy thickness. 𝑑 % 𝑥 More line segments will be drawn 𝑆𝐴 = 2𝜋 j k + 2𝜋 l 2 2 n 𝑠𝑖𝑛B$ 𝑒 2 𝑒 horizontally with an interval of 0.1 inch (projected length also) starting 5.2. Direct measurement from the line segment at the top to Narrow strips of masking tape will be the line segment at the bottom. cut and used to cover the surface of The two regions (A1 and A2) at the the sample chicken egg. end are assumed to be a segment of The strips will then take out from the spheres. egg and laid out in a piece of paper On the other hand, the sections (A3) Using a caliper or image analysis, the between the two ends will be area of the laid out strips is assumed to be cylinder with heights determined to approximate the Δy and diameters di. surface area of the chicken egg The surface area of the egg will be computed using the formula of the surface area of the sphere for the two regions and the surface area of cylinder for the segments in between them. The equation for each region is as follows 𝑆𝐴$ = 2𝜋𝑟$ ℎ 𝑆𝐴% = 2𝜋𝑟% ℎ Q 𝑆𝐴+ = 𝜋∆𝑦 i 𝑑# #R$ where: 𝑆𝐴# = surface area of region 𝑖, 𝑖 =1,2,3 𝑟 = radius of a segment of a sphere ℎ 𝑑% 𝑟 = + h 2 8ℎ d Strictly for PERSONAL USE ONLY. Do not reproduce. ABE 56 First Semester AY2024-2025