10 Flashcards
Example of quality defect
Fat bloom: discoloration due to fat crystallization on the surface.
Quality assurance
Involves taking measures to ensure processing steps are performed properly to ensure consistent quality of finished products
Appearance attributes of QC
Color: human eye, spectrophotometer (transparent liquids), tristimulus colorimeter =objectively. Color difference measurements are used because more sensitive, like a standard plate is made to represent desired color. Sophisticated color monitoring tools are much more common and enable product color to be better controlled and quality enhanced.
Viscosity and textural attributes of QC
Rheology: study of the deformation and flow of matter.
Subjective descriptors describe rheological characteristics of a product.
Objectively: for fluids we use Bostwick consistometer to measure the time it takes for a viscous fluid to flow down an inclined plane and numerical measurements can also be used by viscometers.
For solids and semi-solids, we measure texture and not viscosity. We measure the Force required for deformation of a material, like compression, shear, tension or combination (chewing). Also, Instron Universal Testing Machine is used with bunch of accessories to mimic food forces. Texture and viscosity changes over time and processing but we try to keep it as best as possible.
Flavor attributes of QC
Gas chromatography for volatile compounds associated with aroma, conductivity for salt concentration, pH meters for acidity and refractometers for sugar concentration. But no instrument has replaced humans yet so we do consumer taste panels and sensory evaluation
Hidden attributes of QC (non-sensory)
Nutritional value is a type of hidden quality attribute. Best-before date. Accelerated storage trials are conducted to determine best before dates (elevated temperatures). In-house quality considerations impact the final quality like plant sanitation and microbiological quality.
Unit operation definition
Food manufacturing processes subdivisions = unit operations.
Material handling
Harvesting, transport of product to processing plant, pneumatic conveying of powders (flour,sugar) in trucks, bins. Must be carried out under sanitary conditions, minimize losses of raw materials, maintain quality, minimize microbial growth. Liquid nitrogen is used to cool fruits and veggies at harvest. Includes also in-plant conveying of materials like pumping of liquids. Pumps and all other equipment in contact with food require sanitary design.
Cleaning-related operations
All raw materials are contaminated to some degree and require some cleaning operation. Purification of water, evisceration of animals, washing of eggs, removal of mud from oysters, removal of metal fragments from bulk grain with magnetic metal separator. Also includes cleaning of processing equipments, CIP (cleaning-in-place) exist for automated liquid processing equipment, but other types have to be disassembled
Separation-related operations
Solid from solid: peeling of potatoes (most important step), shelling of nuts. Liquid from liquid: separate cream from milk, centrifugation. Solid from liquid: whey proteins from whey. Liquid from solid: pressing juice from fruit, whey from curd
Disintegration-related operations
Reduction in size like slicing of potatoes, grinding meat, milling wheat for flour, homogenization of milk (reduction in fat globule size) filleting of fish.
Mixing related operations
Solid-solid: dry ingredients like soup mix
Solid-liquid: sugar and water like paddles and propeller
Liquid-liquid: oil and water (emulsions) high pressure homogenizers
Gas-solid: incorporate air into ice cream, various types of mixers and beaters.
Heat-transfer related operations
Roasting, cooking, canning, pasteurization, microwave heating, extrusion. Cooling process often have purpose of extending shelf life but not always (ice cream). Includes freezing processes as well
Evaporation-concentration related operations
May require vacuum because of heat sensitivity so we reduce pressure to reduce boiling water to have higher quality
Drying related operations
Reduce water activity and weight.