food characteristics

Handout MK Pengawasan Mutu 2011/2012 FOOD CHARACTERISTICS Physical Chemical Food Characteristics Biological & Microbiological Sensory Physical Shape Color Food Characteristics Size Surface condition Texture Freshness Defects Total solids, etc Appearance Chemical Nutritional value Food Characteristics Moisture content Functional value pH Food additives Chem contaminants Etc Biological & Microbiological Total bacteria Food Characteristics Total coliform bacteria Total mold Free from pathogenic mos Etc Sensory Flavor Food Characteristics Aroma Taste Texture Etc Physical Attributes • Physical attributes of food are related with the appearance of food products, including: – Color Appearance – Shape The first – Size impressio – Texture n – Etc COLOR  Color is the one of the most important image features because it contains the basic human vision  Color significantly affects the consumer perception of quality  If the color is unacceptable, the other two major quality factors, flavor and texture, are not likely to be judged at all Size  Area has become a very popular measurement for the quality evaluation of fruit and vegetables such as the determination of tomato ripeness  Length measurements might also be used especially for those long shape food products such as cucumber, banana, which usually measured by skeleton length, mid-line of the products Skeleton length Size • In meat industry, the calculation of surface area and volume of ellipsoid meat joints can be used to determine shrinkage during processing • The measurement of area is also important in meat - the area of marbling/intramuscular fat and the overall area to determine the marbling score Size • Size features can also be used for sorting of fish, and many other products such as pizza, wheat grains Shape • Shape is generally referred to the profile or physical structure of objects geometrically • Conventional measurements of shape called size dependents - try to combine different size parameters together to form dimensionless expressions for shape description Shape • Some shape measurements applied to food industries: – Compactness: the ratio of area over the square perimeter - effective for perfect circle food products – Elongation: the ratio of major axis over the minor axis – Convexity: the ratio of convex perimeter over the perimeter – Roughness: the ratio of area over the square major axis Shape • However, those measurement are doubted Are they sufficient enough for describing the shape of food products, especially those with the irregular shape, such as broccoli, the whole body of fish, etc • Some size independent measurements are developed: – Spatial moment – Boundary encoding – Fourier descriptor Texture • Texture can be generally correlated to the sensory properties of food products • Texture can also be used to determine chemical or physical properties of food products - contain more information about chemical or physical properties than color and size • Textural properties of food product will be change during storage • The importance of texture in the overall acceptability of foods varies widely, depending upon the type of food: Texture • Critical: Food in which texture is the dominant quality characteristic, such as meat, potato chips, cornflakes, etc • Important: Food in which texture makes a significant but not a dominant contribution to the overall quality, for example most fruits, vegetables, cheeses, bread, cereal based foods, candy, etc • Minor: Food in which texture makes a negligible contribution to the overall quality, for example most beverages, thin soups, etc Texture Some of common texture vocabs:           Crisp Dry Juicy Creamy Crunchy Chewy Smooth Hard Tender Soft           Fatty Watery Sticky Tough Greasy Slippery Firm Coarse Springy etc Texture • The textural properties of food are group of physical characteristics that arise from the structural elements of food, are sensed primarily by the feeling of touch, are related to the deformation, disintegration, and flow of the food under a force and are measured objectively by function of mass, time and distance Texture • Relation between textural parameters and popular nomenclature: – Mechanical characteristics Primary parameters Secondary parameters Hardness Cohesiveness Popular terms Soft – firm – hard Brittleness Chewiness Gumminess Crumbly – crunchy – brittle Tender – chewy – tough Short – mealy – pasty – gummy Texture Primary parameters Secondary parameters Popular terms Viscosity Thin - viscous Elasticity Plastic – elastic Adhesiveness Sticky – tacky - gooey Texture – Geometrical characteristics Primary parameters Secondary parameters Popular terms Particle size and shape Gritty, grainy, coarse, etc Particle shape and orientation Fibrous, cellular, crystalline, etc Texture – Other characteristics Primary parameters Secondary parameters Moisture content Fat content Popular terms Dry – moist – wet watery Oiliness Greasiness Oily Greasy Source: Bourne (2002) References • Bourne, M.C (2002) Food Texture and Viscosity: Concept and Measurement 2nd Ed Academic Press New York • Francis, F,J (1995) Quality as influenced by color Food Quality and Preference : 149-155 • Zheng, C., Sun DW., and Zheng L (2006) Recent developments and applications of image features for food quality evaluation and inspection – a review Food Science and Technology 17: 642-655 [...]... properties than color and size • Textural properties of food product will be change during storage • The importance of texture in the overall acceptability of foods varies widely, depending upon the type of food: Texture • Critical: Food in which texture is the dominant quality characteristic, such as meat, potato chips, cornflakes, etc • Important: Food in which texture makes a significant but not a dominant... the shape of food products, especially those with the irregular shape, such as broccoli, the whole body of fish, etc • Some size independent measurements are developed: – Spatial moment – Boundary encoding – Fourier descriptor Texture • Texture can be generally correlated to the sensory properties of food products • Texture can also be used to determine chemical or physical properties of food products... based foods, candy, etc • Minor: Food in which texture makes a negligible contribution to the overall quality, for example most beverages, thin soups, etc Texture Some of common texture vocabs:           Crisp Dry Juicy Creamy Crunchy Chewy Smooth Hard Tender Soft           Fatty Watery Sticky Tough Greasy Slippery Firm Coarse Springy etc Texture • The textural properties of food. .. Sticky Tough Greasy Slippery Firm Coarse Springy etc Texture • The textural properties of food are group of physical characteristics that arise from the structural elements of food, are sensed primarily by the feeling of touch, are related to the deformation, disintegration, and flow of the food under a force and are measured objectively by function of mass, time and distance ... because the brain anticipates what the color should be Factors affecting color  In food products, it is possible to make products look better or worse depending on the lighting  Lighting in supermarkets is designed for the ability to make product more favorable But no single lighting arrangement is optimum for every food product Example : Cranberry juice under normal fluorescent tube light with a high... to combine different size parameters together to form dimensionless expressions for shape description Shape • Some shape measurements applied to food industries: – Compactness: the ratio of area over the square perimeter - effective for perfect circle food products – Elongation: the ratio of major axis over the minor axis – Convexity: the ratio of convex perimeter over the perimeter – Roughness:... Many studies have shown that solutions colored dark red will perceived to be sweeter than others of the same sucrose concentration in lighter colors or distilled water Color scales • There are three characteristics of light by which a color may be specified: hue, saturation, and brightness • Hue is an attribute associated with the dominant wavelength in a mixture of light waves, i.e., it represents... Size • Some other measurements of size: – Feret’s diameter: determined by the distance of 2 pixels with the smallest and the largest coordinates – Major axis: the longest line that can be drawn across food products, calculated by measuring the distance between two boundary pixels and by taking the longest – Minor axis, which the longest line that can be drawn through the object perpendicular to the... become a very popular measurement for the quality evaluation of fruit and vegetables such as the determination of tomato ripeness  Length measurements might also be used especially for those long shape food products such as cucumber, banana, which usually measured by skeleton length, mid-line of the products Skeleton length Size • In meat industry, the calculation of surface area and volume of ellipsoid... index of quality  Color measurement can be used to evaluate pigment content (carotenoid, anthocyanin, chlorophyl, etc.)  Colorimetry and chromatography can be used to measure the pigment content of food product Factors affecting color  Effect of lighting  The type of light falling on a object will affect the perception of color  For example, when green light is directed onto a white sheet of ... Chemical Nutritional value Food Characteristics Moisture content Functional value pH Food additives Chem contaminants Etc Biological & Microbiological Total bacteria Food Characteristics Total coliform...Physical Chemical Food Characteristics Biological & Microbiological Sensory Physical Shape Color Food Characteristics Size Surface condition Texture Freshness... pathogenic mos Etc Sensory Flavor Food Characteristics Aroma Taste Texture Etc Physical Attributes • Physical attributes of food are related with the appearance of food products, including: – Color