muttu phm[1].pptx.........................

muttu phm[1].pptx.........................

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  KELADI SHIVAPPA NAYAKAUNIVERSITY OF AGRICULTURE AND HORTICULTURAL SCIENCES, SHIVAMOGGA. TOPIC: PRESERVATION BY DRYING AND DEHYDRATION Submitted to: Dr. Ravishankar. M. Patil Assistant professor Dept of Post harvest technology COA, Shivamogga. Submitted by: Muttanna Jr. M. Sc MH2TBD0365 Dept of Fruit Science COA, Shivamogga
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  DRYING
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  Drying : • Itis the application of heat under controlled condition to remove water by evaporation. • One of the oldest method of preservation food. • Removes moisture and stops the growth of bacteria, yeasts and molds that spoil food Drying can be achieved through: • natural methods such as air drying or sun drying, • artificial means like using heat, dehumidification, or vacuum technologies making them suitable for storage, transportation, or consumption
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  1. Natural Drying SunDrying: Using sunlight to dry materials like grains, fruits, or fish. Common in agriculture. Air Drying: Uses ambient air (with or without natural airflow) without external heat sources. 2. Convective (Hot Air) Drying Uses heated air that flows over the material to remove moisture. Examples:Tray dryers,Tunnel dryers,Spray dryers,Fluidized bed dryers Types Of Drying
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  3. Conductive (Contact)Drying Heat is transferred directly from a hot surface to the material. Examples:Drum dryers,Vacuum shelf dryers 4. Radiative Drying Uses electromagnetic radiation (usually infrared or microwaves) to heat the material. Examples:Infrared drying,Microwave drying
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  Types of drying: •Air drying • Sun drying • Oven drying • Freeze drying • Spray drying • Vacuum drying etc
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  DEHYDRATION
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  Dehydration : • Itis the process of removal of moisture by the application of artificial heat under controlled conditions of temperature, humidity and air flow. • Dehydration is a specific type of drying process. Dehydration methods commonly include • Heat, airflow, and desiccants (substances that absorb moisture) to facilitate the removal of water. • This process is extensively used in food preservation, pharmaceuticals, and the production of materials like leather or dried flowers, where maintaining the integrity of the product is essential
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  Dehydration techniques: • SolarDehydration • Osmotic Dehydration • Vacuum Dehydration • Spray Dehydration • Freeze Dehydration (Freeze-Drying) • Microwave Dehydration etc
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  Aspect Renewable MethodsNon-Renewable Methods Definition These use energy sources that are naturally replenished and sustainable over time. These rely on finite sources of energy like fossil fuels (coal, natural gas, electricity from non- renewable sources). Energy source Natural, sustainable sources Fossil fuels or electricity from non-renewable sources Common energy types Solar, wind, biomass Electricity (from coal, gas), diesel, LPG Environmental impact Low or zero emissions High emissions, carbon footprint Operating cost Low (after setup) High (due to fuel or electricity costs) Examples of drying methods - Solar drying (direct/indirect) - Sun drying (open-air) - Electric dryer - Gas-fired dehydrator - Microwave drying Initial investment Moderate to low Moderate to high Drying time Longer (weather-dependent) Shorter, consistent Renewable and non renewable methods of drying:
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  Principle of dryingand dehydration: • Drying is the process of moisture removal from the product. • Since foods are hydroscopic material which can either absorb or desorb moisture from the air or its surroundings depending on the difference in vapour pressure. • Moisture transferred from a higher vapour pressure, to the lower one.
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  Importance of drying& dehydration: • Minimizes microbial spoilage. • Continuous supply of product throughout the year. • Better quality products. • Make products available during off season. • Minimum cost for packaging, handling and transportation. • Improved milling and mixing
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  Drying Dehydration Drying mainlyremoves moisture from a solid, semi- solid or a liquid food product Dehydration removes water from a water containing compound It is done using controlled conditions It is carried under controlled conditions and sophisticated equipment Losses of fruit quality Less or minimised Time consuming Less time Cheapest method Expensive method Eg: Dried beans and Peas, Raisins, Dates, Apricots Eg: Powdered lemon, Apple chips Difference between drying and dehydration:
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  FRUIT PROCESS Apple Peel,core and slice into 3/8-inch rings, or cut into 1/4-inch slices. Pretreat and dry 6-12 hours until pliable Apricot Cut in half and turn inside out to dry. Pretreat and dry 8-20 hours until pliable Banana Peel, cut into 1/4-inch slices and pretreat. Dry 8-16 hours until pliable or almost crisp. Blue berries Dry 10-20 hours until leathery. Cherry Cut in half and dry 18-26 hours until leathery and slightly sticky. Peach Peel, halve or quarter. Pretreat and dry 6-20 hours until pliable Pear Peel, cut into 1/4-inch slices, and pretreat. Dry 6-20 hours until leathery. Pineapple Core and slice 1/4-inch thick. Dry 6-16 hours until leathery and not sticky. http://farmgal.tripod.com/Dehydrate.html Fruit drying guide:
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  Pre-treatment: • Some fruitsneed to have their enzymes inactivated before drying, especially those that oxidize when exposed to air (e.g. bananas, apples, pears) • Ascorbic Acid • Fruit juice dip • Honey dip • Syrup blanching • Commercial acids Preparing fruit for drying: • Rinse fruits under cold running water. • Cut away bruised portions and remove seeds. Pre-treatment: • Blanching: Blanching is briefly precooking food in boiling water or steam, and it is used to stop enzymatic reactions within the foods. Blanching also shortens drying time and kills many spoilage organisms
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  Steps for waterblanching: • Use a blancher or a deep pot with a tight-fitting lid. • Fill the pot two-thirds with water, cover, and bring to a rolling boil. • Place fruits into a wire basket and submerge them into the boiling water for the recommended time. • Remove fruit and place in cold water to stop cooking. • Drain and place fruits on drying tray Steps for syrup blanching: • Combine 1 cup sugar, 1 cup light corn syrup, and 2 cups water in a pot. • Add 1 pound of fruit. • Simmer 10 minutes. • Remove from heat and keep fruit in syrup for 30 minutes. • Remove fruit from syrup, rinse, drain, and continue with dehydration step.
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  • Sulphuring/Sulphiting: • Mostfruits are treated with sulphur dioxide by placing them in a closed chamber in which sulphur (3 g/kg of fruit) is burned so that the fruits can absorb SO fumes. ₂ The process is called sulphuring or sulphur fumigation. • Sulphiting, on the other hand, refers to the immersion of prepared fruits or vegetables in a solution of potassium meta-by-sulphite to serve the same purpose as sulphiting. • Sulphuring helps preserve color, prevents browning, and reduces the destruction of carotene and ascorbic acid, in addition to preventing spoilage of the dried product.
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  • POST DRYINGTREATMENTS: • After drying, foods undergo sweating, packaging, and potentially pasteurization to ensure quality and safety. 1. Sweating - involves storing dried foods in bins to equalize moisture content. 2. Packaging - protects against moisture, microorganisms, and insects. 3. Pasteurization - eliminates pathogens, typically with a heat treatment of 30-70 minutes at 65 - 85 0 C. 1. Sweating: • This post-drying process involves storing dried foods, like almonds and walnuts, in bins or boxes. • This allows for moisture equalization, ensuring a uniform moisture content throughout the product. • It can also involve adding moisture to reach a desired level.
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  2. Packaging: • Mostdried foods are packaged soon after drying to protect them from moisture, microbial contamination, and insect infestation. • While some dried fruits may be stored for up to a year before packaging, prompt packaging is generally recommended. 3. Pasteurization: • Pasteurization is a heat treatment used to eliminate harmful pathogens that might be present in dried fruits. • The treatment is typically applied in the package and involves heating the fruit for 30-70 minutes within a temperature range of 65 to 85 0 C.
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  After Drying Fruit: •Cool fruit 30-60 minutes before packaging. • Don’t pack too soon or moisture buildup could occur. • Don’t wait too long or the fruit could pick up moisture from the air. Conditioning Fruit: • Conditioning is used to equalize moisture  Pack cooled fruit in plastic bag or glass jar  Seal and let stand for 7-10 days  Shake jars daily to separate pieces and check for moisture (condensation on sides of bag/jar) • If there is condensation, return fruit to dehydrator for more drying or place in freezer. • There is a chance mold will have already started growing in too-moist fruit; discard if you find mold.
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  Drying techniques: • SunDrying • Vacuum Dryer • Solar Dryer • Freeze Dryer • Osmatic Dehydration • Oven Dryer • Tray Dryer • Tunnel Dryer • Roller or Drum Dryer • Bin Dryer • Belt Dryer
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  1. Sun drying: •To dry in the sun, hot dry days are best. • A minimum temperature of 86 °F is needed with higher temperatures being better. • It takes several days to dry fruits out-of-doors. Because the weather is uncontrollable. • Sun drying can be risky. Also, the high humidity in the South is a problem. • Humidity below 60 percent is best for sun drying.
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  2. Vacuum drying: •Vacuum drying is an important process for heat sensitive materials. • The process of vacuum drying can be considered according to physical condition used to add heat and remove water vapour. • Low temperature can be used under vacuum for certain methods that might discolor or decompose at high temperature. • It is considered too costly for large scale production of commodity.
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  3. Solar dryer: •Recent efforts to improve on sun drying have led to solar drying. • Solar drying also uses the sun as the heat source. • A foil surface inside the dehydrator helps to increase the temperature. Ventilation speeds up the drying time. • Shorter drying times reduce the risks of food spoilage or mould growth.
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  4. Freeze drying: •Freeze-drying, also known as cryo-desiccation. • It is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport. • Freeze-drying works by freezing the material and then reducing the surrounding pressure to allow the frozen water in the material to sublimate directly from the solid phase to the gas phase
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  Working principle offreeze dryer: • Freeze drying is also called as lyophilization. It is the removal of water in the form of vapour directly from the frozen state (ice), without changing into the liquid state. • Material is dried by exposing it to a temperature and pressure below its triple point. • However, the temperature must be below the eutectic point during the process. • Under these conditions the heat supplied acts as latent heat and sublimation occurs (i.e., conversion of solid into vapour). • These formed water vapours are eliminated by passing it through a condenser, which is maintained at a temperature lower than the temperature of frozen material.
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  5. Osmotic dehydration(OD): • Osmosis is known as a partial dehydration process. • Although it does not remove enough moisture to be considered as a dried product, the process has the advantage of requiring little energy. • It works well as a pre-treatment prior to drying by other methods. • The advantage of OD is its lower energy use and lower product thermal damage since lower temperatures used allow the retention of nutrients. • Main advantages of using OD as the reduction of process temperature, sweeter taste of dehydrated product, reduction of 20– 30% energy consumption and shorter drying time.
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  6. Oven drying: •An oven is ideal for occasional drying of fruit leathers, it may not be satisfactory for preserving abundant garden produce. • Oven drying is slower than dehydrators because it does not have a built-in fan for the air movement. (However, some convection ovens do have a fan). • It takes about two times longer to dry food in an oven than it does in a dehydrator. Thus, the oven is not as efficient as a dehydrator and uses more energy.
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  7. Tray dryer: •In tray, the fruit spread out thinly. • Heating may be by an air current sweeping across the trays by conduction from heated trays or heated shelves on which tray lies. • Most tray dryer heated by air, which also remove moist vapours.
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  8. Tunnel dryer: •These may be regarded as developments of the tray dryer, in which the trays on trolleys move through a tunnel where the heat is applied and the vapours removed. • In most cases, air is used in tunnel drying and the material can move through the dryer either parallel or counter current to the air flow. • Sometimes the dryers are compartmented, and cross- flow may also be used.
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  9. Roller orDrum dryer: • In these the fruit is spread over the surface of a heated drum. • The drum rotates, with the food being applied to the drum at one part of the cycle. • The food remains on the drum surface for the greater part of the rotation, during which time the drying takes place, and is then scraped off. • Drum drying may be regarded as conduction drying.
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  10. Bin dryers: •In bin dryers, the foodstuff is contained in a bin with a perforated bottom through which warm air is blown vertically upwards, passing through the material and so drying it.
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  11. Belt dryers: •The fruit is spread as a thin layer on a horizontal mesh or solid belt and air passes through or over the material. • In most cases the belt is moving, though in some designs the belt is stationary and the material is transported by scrapers.
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  Factor affecting dryrate: • Temperature • Velocity of air • Surface area • Size of product • Tray load • Relative humidity of air 1. Temperature: • Higher temperatures increase the rate of moisture evaporation. • Must be controlled to prevent damage to heat-sensitive materials (e.g., vitamins, enzymes).
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  2. Air velocity: •Increased air flow removes moist air around the product quickly. • Enhances heat and mass transfer, speeding up drying. 3. Humidity of drying air: • Lower relative humidity promotes faster drying. • Moist air slows down moisture removal. 4. Surface area: • Larger surface area allows more moisture to escape. • Sliced, shredded, or spread-out materials dry faster. 5. Thickness of the material: • Thicker layers slow down drying as moisture has a longer path to travel. • Thinner layers dry more quickly and uniformly.
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  6. Type andcomposition of material: • Materials high in sugar, fat, or fiber dry more slowly. • Porosity and structure affect how easily moisture moves out. 7. Drying method: • Convectional, freeze, vacuum, microwave, or solar drying each have different efficiencies and suitability based on the material. 8. Initial moisture content: • Higher initial moisture takes longer to dry. • Affects the choice of drying parameters and equipment. 9. Equipment design: • Uniform airflow, temperature control, and tray design improve efficiency and drying uniformity.
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  Changes during drying: •Food materials do not have perfect elasticity and water is no removed evenly throughout food as it is dried causes shrinkage. • Due to high surface temperature and unbalanced drying, dry skin will form and causes hardening. • Enzymatic browning of products due to poor blanching. • Loss of volatile flavor constituents. • Partial loss of some essential nutrients like Vit C
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  Benefit of driedfruit: • Dried fruits are good sources of phytochemicals. • Dried fruits are an important source of antioxidants in the diet. • Dried fruits, such as prunes, provide pectin, a soluble fiber that may lower blood cholesterol. • Dried fruits, such as raisins, are a source of prebiotic compounds in the diet. • Dried apricots and peaches are good sources of carotenoids. • Dried fruits contain organic acids such as tartaric acid (raisins) and sugar alcohol such as sorbitol (prunes).
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  How dryness offruit can be determined? • Drying fruit can take anywhere from 6 hours for thin or small pieces or 10-12 hours for larger juicy fruits such as peach or apricot halves. • Dried fruit will feel leathery; won’t stick to itself. • Cut fruit should have no visible moisture inside though it may be soft
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  Merits of preservationby drying and dehydration methods: 1. Inhibits microbial growth 2. Extends shelf life 3. Reduces weight and volume 4. Retains nutritional value 5. Cost-effective preservation method 6. Requires no refrigeration 7. Simple and accessible technology 8. Suitable for a wide range of foods 9. Helps reduce food waste 10. Enhances or concentrates flavor in some foods
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  Limitations or Drawbacksof drying and dehydration methods: 1. Loss of heat-sensitive nutrients 2. Altered texture and flavor 3. Risk of microbial contamination during drying 4. Requires airtight storage to prevent moisture reabsorption 5. Time-consuming process 6. High energy consumption in mechanical drying 7. Potential for uneven drying 8. Not effective for all food types 9. Risk of case hardening 10. Dehydrated food may have inferior quality
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  CASE STUDIES -01 Objectives: To study the effects of drying methods on the values on physico-chemical properties of dehydrated tomato powder Ramya et al. (2017)
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  Material and methods: Ramyaet al. (2017)
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  Table 1: Physico-chemicalproperties of fresh tomato and dehydrated tomato powder Yellow colour – Maximum Green colour – Almost same in all Red colour - Minimum Ramya et al. (2017)
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  • This studyconcluded that more better results can be obtained using spray type of driers that can remove moisture rapidly from drying chambers. • It was found that drying of tomato in vacuum dryer gave some advantages with respect to some nutritional contents on in order to obtain products with better sensory and nutritional characteristics and better process yield INFERENCE: Ramya et al. (2017)
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  Objective: To investigatethe micronutrient content of six commonly consumed green leafy vegetables after dehydration by using four different drying methods, i.e. sun drying, shade drying, cabinet dryer and microwave oven drying. CASE STUDIES - 02 Khatoniar et al. (2019)
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  Material and methods: Sixcommonly available green leafy vegetables were selected 1. Amaranthus spinosus 2. Chenopodium album 3. Spinacia oleracea 4. Phyllanthus amarus 5. Talinum triangulare 6. Ludwigia adscendens Dehydration by using four different drying methods, 1. Sun drying 2. Shade drying 3. Cabinet dryer 4. Microwave oven drying. Khatoniar et al. (2019)
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  Lowest Highest Khatoniar et al.(2019) Table.2: Effect of moisture content (g/100g) of the greens after dehydration
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  Table.3 Effect ofascorbic acid content (mg/100g) of the greens after dehydration Minimum retension Maximum retension Khatoniar et al. (2019)
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  • This studyconcludes that the mineral content of all of the selected greens became concentrated after dehydration. • These dehydrated leaves have good rehydration capacity for incorporation into various products to reduce micronutrient deficiency. • Dehydration also increases shelf-life of the greens. • Consumption of dehydrated green leafy vegetables incorporated products in daily diet will ensure micronutrient security INFERENCE: Khatoniar et al. (2019)
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  CASE STUDIES -03 Objective: To assess the effect of some pre-treatments and drying methods on the qualities of dried mango slices. Dereje et al. (2020)
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  Material and methods: Derejeet al. (2020)
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  Table 4. Physicochemicalanalysis result for fresh mango fruit Dereje et al. (2020)
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  Table 5. Thecolour of dried mango as affected by pretreatments and drying methods Dereje et al. (2020)
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  Table 6. Theantioxidants of dried mango as affected by pretreatments and drying methods Dereje et al. (2020)
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  • The resultsof the study showed that dried mango slices were good sources of nutrients and • antioxidants. • Freeze and fluidized bed drying methods produced better dried mango slices with high quality parameters. • Pretreatments were found to be a suitable method for the colour and vitamin C preservation of dried mango fruits. • The best colour and vitamin C parameters were observed with lemon juice and hot water blanching pretreated samples INFERENCE: Dereje et al. (2020)
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  CASE STUDIES -04 Objective: Aimed to determine the effect of freeze drying (FD), hot air drying (HD), vacuum drying (VD), and infrared hot air drying (IRD) on the quality of two kinds of garlic varieties (white and purple garlic) Gong et al. (2022)
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  Material and methods: Gonget al. (2022)
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  Table 7. Thevalues of L*, a*, and b* of the dried white and purple garlic slices. Gong et al. (2022) Red clr – Lowest Yellow clr - Highest
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  Figure 1. Theallicin content of dried white and purple garlic slices. Each value represents the mean of three replicates, and error bars indicate standard deviation (± SD). Different letters (a–d) mean the significant difference between the fresh and drying methods. (p < .05). Different letters (A and B) mean the difference significantly at p < .05 under the same drying methods in different garlic variety. Gong et al. (2022)
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  INFERENCE: Gong et al.(2022) • The different drying treatments (FD, HD, VD, and IRD) can significantly affect the colors, bioactive compounds of white and purple garlic. • The highest whiteness of dried white and purple garlic was obtained in the FD treatment. • FD and IRD treatment can preserve well active substance including allicin of white and purple garlic • Especially, the allicin in dried purple garlic was higher than the white one under the same drying methods
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  CASE STUDIES -05 Objectives: To evaluate the influence of infrared radiation-assisted freeze-drying (IRFD) on the process efficiency and quality of blackberries (Rubus spp. variety Tupy). Oliveira et al. (2023)
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  Material and methods: Oliveiraet al. (2023)
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  Table 8: Textureprofile analysis: sample sizes (cm3 ), hardness (N) and chewiness (J); and bioactive compounds: content of total phenolic compounds (TPC, mg gallic acid/g sample), antioxidant capacity (AC, %) and anthocyanin content (mg/100 g) of drying blackberries (Rubus spp. variety Tupy) subjected to freeze- drying(FD), near-infrared assisted freeze-drying (NIRFD), freeze-drying + near-infrared heating after 40 % weight reduction (NIRFD40%WR), mid-infrared-assisted freeze-drying (MIRFD) and, freeze-drying + mid- infrared heating after 40 % weight reduction (MIRFD40 %WR) Yellow clr – Highest Red clr - Lowest Oliveira et al. (2023)
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  Fig. 2. Effectof different drying methods on the rehydration characteristics of freeze-dried blackberries NIRFD samples had the highest values for RR throughout the entire time, while MIRFD had the lowest values. Oliveira et al. (2023)
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  • NIRFD, whichused continuous short-wave IR lighting, was more efficient than the other treatments, given that it reduced the time for complete dehydration while still preserving bioactive compounds such as total phenols and antioxidants. • It also had high anthocyanin content conclude that IRFD, especially freeze- drying with continuous near infrared radiation heating, has good potential for the production of dried blackberries with high added value, as its final products have a good appearance and high nutritional content while saving time and energy INFERENCE: Oliveira et al. (2023)