Tehnik Pengolahan dasar.ppt

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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