Quality measurement using direct human senses is known as assessment senses (sensory evaluation). Assessment senses, among others, are used to assess the taste, smell, aroma, flavor, appearance (appearance) and sometimes color. With the development of increasingly advanced technology now found a tool capable of measuring multiple factors replacing the sensory quality of the human senses.
The second way instrumental evaluation is used to measure the quality factors that are not directly be assessed by human senses, such as the chemical properties, physico-chemical, physical properties and most of micro-analysis (analysis of microorganisms in materials). To facilitate an understanding of the factors discussed quality of agricultural products will be grouped into physical factors, chemical and microbiological. Keep in mind that in the sorting and grading only physical quality factors are used, while the chemical and microbiological quality factor usually used for the determination of the quality of the product.
Physical deciding factor is the physical properties of materials agricultural products that can be used to determine the level of quality of the material. In this discussion are classified into physical determinants of foodstuffs are: size and shape, color and luster as well as “tekstures” or “kinesthetics”.
1) Size and shape
The size and shape are factors that can be seen real quality and usually can be measured and monitored with ease. Classification of the quality of the material by size and shape is usually the first stage in classifying the level of quality of agricultural produce. This classification can be done by hand (manual) and can also be done by using mechanical devices eg filter and mechanical sorting.
Classification of materials by size and shape is done with the intent to obtain uniformity, the size of agricultural produce and is an indication of the level of maturity of such materials, such materials have a smaller size may indicate the nature of less elderly when compared to the same material at a larger size , Several criteria including the size of the weight, volume, density, density, length, width and the center line (diameter).
While the shape of the material can be seen directly, for example round, oval, symmetrical, curved and so on. Measurement form of quantitatively determined based on a comparison between the length by the width, height or diameter.
The size of the weight of a material can be expressed by the total weight, the average weight, the weight of materials depending on the purpose of unity and purpose. To see the picture and determine the uniformity of materials usually used heavy material unity (x kg per item).
Volume measurement is done by determining the amount of space that can be occupied by the material to be determined the volume. Measurement of volume, there are two ways of “apparent displacement” and “absolute displacement”. In the “apparent displacement” that there is a space between the material to be ignored in the measurement of the material and is usually expressed in the unity of the container eg the number of oranges in a crate, the amount of corn in a crate and so on.
In the “absolute displacement” contained spaces between materials with materials taken into account. To get the measure “absolute displacement” solid material is dipped into the liquid in a measuring cup. The difference in fluid volume dipped after the previous material shows the volume of material. For example, the volume of water in a measuring cup before the material is dipped in 10 ml, after the materials incorporated into a 12 ml volume increases.
Thus the material volume is 2 ml. For small-sized material, measuring the volume of material is done by dipping the material in a certain amount at once. For example, 100 pieces of green beans dipped in water on a glass surface measuring raise the limit of 200 ml to 400 ml, then the volume of beans is 200 ml per 100 pieces of green beans or 2 ml per fruit beans.