Food Preparation Conceptual Reviewer

FOOD PREPARATION WET PROCEDURE RAW MATERIAL PREPARATION Soaking Are unit operations done to ensure that foods...

FOOD PREPARATION WET PROCEDURE RAW MATERIAL PREPARATION Soaking Are unit operations done to ensure that foods Spraying with a uniformly high quality are prepared for flotation washing subsequent processing. ultrasonic cleaning Highly cost-effective method of improving the quality of the raw material. DRY PROCEDURE Includes: Cleaning, sorting, grading, and peeling. Separation by air Magnetism CLEANING Other physical methods Unit operation that removes contaminants. WET CLEANING Prepares surface of food in suitable condition for further processing. Employs water Should take place at the earliest stages of the more effective than dry methods for removing process soil from root crops or dust and pesticide The selection of a cleaning procedure is residues from soft fruits or vegetables. determined by the nature of the product to be Dustless cleaned and by the types of contaminant to be Causes less damage to food removed ADVANTAGES OF WET CLEANING EXAMPLES OF CLEANING OPERATIONS Flexibility in operations: can use different Peeling fruits and vegetables combinations of detergent and sterilant at Skinning meat different temperatures. Descaling fish Water can be recirculated, filtered, and Blanching vegetables chlorinated. WHAT CLEANING PREVENTS DISADVANTAGES OF WET CLEANING damage to equipment because of stones, bone Warm cleaning water may accelerate chemical or metals. and microbial spoilage. overly large time and money costs spent on Produces large volumes of effluents with high processing contaminants BOD and COD. subsequent loss of the remaining bulb by Needs costly and high amount of cleaning water. microbial growth during storage or delays before High effluent disposal and water treatment processing charges. Overall, cleaning reduces food wastage, improve EXAMPLES OF WET CLEANING EQUIPMENTS economics, and protects the consumer Spray Washers CONTAMINANTS FOUND IN FOOD Brush Washers Drum or Rod Washers Ultrasonic Cleaners Floatation Tanks DRY CLEANING Used for products that are smaller, have greater mechanical strength and possess a lower moisture. ADVANTAGES OF DRY CLEANING Smaller and cheaper equipment Produces a concentrated dry effluent which is cheaper to dispose Plant Cleaning is simpler Chemical and microbial deterioration of food is reduced. DISADVANTAGES OF DRY CLEANING Additional capital expenditure may be necessary. MAIN GROUP OF DRY-CLEANING EQUIPMENT Screen capacity is influenced by factors such as: Air classifiers - Particle shape Magnetic separators - Size distribution Separators based on screening of foods - Sieve material CLASSIFIERS - Shaking amplitude and frequency - Methods to prevent sieve blockage Uses a moving stream of air to separate Commonly used for sorting dry foods (flour, contaminants from foods. sugar, spices) Utilizes difference in densities Moisture can cause issues like particles sticking Widely used in harvesting machines to separate or clumping together heavy contaminants from light contaminants VARIABLE APERTURE SCREENS REMOVING CONTAMINANTS AND FOREIGN BODIES Have either gradually widening or stepwise CONTAMINANTS WITH REGULAR WELL- increasing apertures. DEFINED SHAPES: Removed by conveyors, disc Gentler than drum screens separators, and screens. Suitable for delicate foods like fruits. CONTAMINATION BY METAL FRAGMENTS: Continuously variable screens use diverging Removed by either permanent or rollers, cables, or conveyor belts to align and sort electromagnets. food based on its smallest dimension. CHECKING CONTAMINATION IN SMALL- Stepwise screens adjust gaps between rollers PARTICULATE FOODS: Automatically checked and a conveyor belt to sort food by a consistent for contaminants using microprocessor dimension, such as the core diameter of a fruit. controlled colour sorting equipment IMAGE PROCESSING USING X-RAYS Sorts foods based on length, diameter, surface Used to detect metals and other types of solid defects, orientation, and color. contaminant in both raw materials and inside packaged foods. COLOR SORTING limited to products that are larger than 15 cm Manual sorting by color is still widely used but is mainly applied to glass jar inspection increasingly expensive in labor cost, operator NEW DEVELOPMENTS IN X-RAYS training, and space requirement. X-ray sensitive elements which collect a sample MACHINE VISION SORTING SYSTEMS of information as the product passes over the Monochrome (Black & White) sensors Bichrome (4100 shades of red & green) include detection of stones, bone fragments, Trichromatic or full color (262 000 shades of red, plastics, seafood shells and ceramics or concrete green, and blue) with optional infrared in addition to metals, and also bag-in-box packaging and metallised pouches. CHUTE-TYPE COLOR SOTERS SORTING commonly used for food, as prices are lower, capacities are higher, and products can be seen separates foods into categories based on more easily from both sides measurable physical properties are usually applicable to specific products, as the should be done early to ensure uniformity in chute is designed with special channels for this processing. kind of material based on size and shape of the The four main properties used are size, shape, material weight, and color. The shape and size of foods are crucial for BELT-TYPE COLOR SORTERS processing and retail value Convey material from feeding port to the output Uniform shapes improve efficiency and market port steadily. appeal. recognized by HD industrial camera. Material Shape sorting can be manual, mechanical, or with abnormal or unwanted colors will be done through image processing removed by air ejectors. Near the output port, FIXED APPERTURE SCREENS the material will be Two common fixed aperture screens: flatbed WEIGHT SORTING screen (sieve) and drum screen (rotary screen) more accurate than other methods and is Multideck flatbed screen uses multiple mesh therefore used for more valuable foods layers with varying aperture sizes (20 micrometers to 125 millimeters) Separates particles by gravity ASPIRATION AND FLOATATION PEELING This sorting equipment exploits differences in used in fruit and vegetable processing to remove food density to sort food. inedible parts and enhance appearance Example: The density of peas correlates with goal is to minimize costs by reducing waste and their tenderness and sweetness: denser, starchy keeping the peeled surface clean and and overmature pieces sink and are separated undamaged. from the required product, which floats in the FIVE MAIN PEELING METHODS brine. 1. Flash Steam Peeling COLLATION OF FOOD 2. Knife Peeling refers to the process of gathering or assembling 3. Abrasion Peeling various types of food 4. Caustic Peeling often laborious and time consuming FLASH STEAM PEELING Normally performed by operators who select items from a pool of materials and collect them Root crops (and similar foods) are fed in batches by trial and error into a pack which is as close as into a rotating pressure vessel (4–6 rpm). possible to the required weight. High-pressure steam (1500 x 10³ Pa) is now performed automatically by a introduced to expose all food surfaces to the microcomputer. steam. Items of food are weighed and placed in a The time of exposure varies depending on the magazine then the microcomputer then selects type of food. the best combination of items to produce the High temperatures quickly heat the surface desired number in a pack, with minimum (within 15–30 seconds), but the low thermal giveaway conductivity prevents further heat penetration, so the product does not cook. GRADING Texture and color are preserved. GRADING: assesses overall quality based on multiple Instant pressure release causes steam to form attributes under the skin, resulting in the surface "flashing off." SORTING: Separates items based on single characteristics. Can be part of grading Most peeled material is discharged with the steam. GRADING PROCESS: Conducted by trained operators Water sprays are used only to remove any who evaluate multiple variables at once remaining traces. This type of peeler is becoming popular due EXAMPLES OF GRADING to: EGGS: Inspected visually using ‘candling’ to check for - Lower water consumption factors like fertilization, malformation, blood spots, or - Minimal product loss rot - Good appearance of peeled surfaces - High throughput (up to 4500 kg/h) MEATS: Inspected for disease, fat distribution, bone-to- - Automatic control of the peeling cycle flesh ratio, carcass size, and shape. Technological - Production of easily disposable advancements, such as image processing, are used for concentrated waste more detailed inspections (e.g., bruising, skin color, damage) KNIFE PEELING CHEESE AND TEA: : Graded based on flavor, aroma, and Stationary blades are pressed against the surface color. of rotating fruits or vegetables to remove the APPLES: Graded using colored cards to assess color skin. distribution, surface blemishes, size, and shape Stationary blades are pressed against the surface of rotating fruits or vegetables to remove the LABORATORY ANALYSIS: Some food grades are skin. determined by lab analyses (e.g., wheat flour assessed Suitable for citrus frits where skin is easily for protein content, dough extensibility, color, moisture, removed and there is little damage or loss of insect presence). fruit. COST AND QUALITY: Grading is more expensive than ABRASION PEELING sorting due to the need for skilled operators, but it results in a more uniform, high-quality product that Food is fed onto carborundum drum or rollers or assesses multiple non-automatable attributes placed in a rotating bowl lined with carborundum. Abrasive surface removes the skin, washed away by water. ADVANTAGES OF ABRASION PEELING Low energy costs (operates atroom temperature) Low capital costs No heat damage to food Good surface appearance LIMITATIONS OF ABRASION PEELING Higher product loss compared to flash peeling (25% vs. 8–18%) Production of large volumes of dilute waste Difficult and expensive waste disposal Relatively low throughput as food needs to contact abrasive surfaces CAUSTIC PEELING Material to be peeled is passed through a dilute sodium hydroxide solution (1–2%). Sodium hydroxide softens the skin, allowing it to be removed by high-pressure water sprays. Dry caustic peeling: - Material is dipped in a 10% sodium hydroxide solution. - Softened skin is removed using rubber discs or rollers. Drawback of caustic peeling: it causes decolorization of the product. FLAME PEELING utilizes a conveyer belt to transport and rotate the material through a furnace heated to temperatures above 1000°C. The skin is burned off and then removed by high pressure water sprays.