Pra-treatment (Raw Material Preparation)Yosfi Rahmi S.Gz. MSc. Jurusan Gizi Fakultas Kedokteran Unibraw Malang 2011
BackgroundCleaning, Sorting, grading or peelingHigh quality foodFurther processingFood after harvesting(variation and contaminants)
CLEANINGDefinition:Process where contaminating materials are removed from the food and separated to leave the surface of the food in a suitable condition for further processing
Peeling (fruits and vegie), skinning meat or descaling fish considered as cleaning process
CLEANINGContaminants on raw foods
CLEANINGShould take place at the earliest opportunity in a food process to:Prevent damage to subsequent processing equipment by stones, bone or metalsPrevent time and money from being spent on processing contaminantsReducing food wastageImprove the quality of final productProtecting the consumer
Cleaning ProcedureWet CleaningDry Cleaning
The selection of cleaning procedure is determined by:The nature of the product to be cleanedThe type of contaminant to be removedIn general, more than one type of cleaning procedure is required to remove variety of contaminants on food
Wet CleaningMore effective than dry methods for removing soil from root crops or dust and pesticide residues from soft fruits/vegieDustless and causes less damage to foods than dry methodsRecirculated, filtered, and chlorinated water is used whenever possible to reduce costsThe equipment include spray washers, brush washers, drum or rod washers and flotation tanks
Wet Cleaning
Dry CleaningUsed for smaller productUsed for product have greater mechanical strength and possess a lower moisture contentEx. grains and nutsAfter cleaning, the surface are dry preservationBut, produce dust
Dry CleaningMain groups of equipments:Air classifiersMagnetic separators andSeparators based on screening of foods
Dry Cleaning
SORTINGDefinition:The separation of foods into categories on the basis of a measurable physical propertySizeShapeWeightColour
Purpose: to ensure a uniform product for subsequent processing
GRADINGDefinition:The assessment of a number of attributes to obtain an indication of overall quality of a food carried out by trained operators in some cases, the grade of food is determined from laboratory analyses results
PEELINGDefinition:Process to remove unwanted or inedible material and to improve the appearance of the final product
5 main methods of peeling: Flash steam peeling Knife peeling Abrasion peeling Caustic peeling Flame peeling
SIZE REDUCTIONBecause of grinding, compression or impact forcesBenefit of Size reduction in food processing:Increase rate of drying, heating or cooling and improves the efficiency and rate of extraction of soluble componentImportant for the correct functional or processing properties of some productsMore complete mixing of ingredients
SIZE REDUCTIONClassification of the Methods:Solid foodChopping, cutting, slicing and dicingMilling to powders or pastes (comminution)Fluid food:Emulsification and homogenisation
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