Application of Evaporators in Fruit and Vegetable Processing

Submitted to: Submitted By: Preeti Birwal

Dr. Rekha Menon PhD (DE)

NDRI

Introduction

The process of evaporation is widely used to concentrate foods

Evaporation technology is a process of separating substances by means of thermal energy. The concentrated liquid, which is still pump able, usually is the desired final product.

Three element: Heat transfer, Vapor-liquid separation and vapor condensation

Objectives

To reduce water activity and lengthen shelf life

To reduce packaging, transportation, and storage cost (Reduction in bulkiness)

To improve the stability and handling of the product.

It may be used as an economical preparatory step for subsequent dehydration, as in the cases of spray drying, drum drying, vacuum drying, freeze-dried, crystallization and mixing (Food mixing).

Pre-concentration reduces cost of energy for subsequent processes.

Concentrate as commodity is easier to market.

Applications

Evaporators are used in a wide range of processes, including pharmaceuticals, foods, beverages, juices dairy industry, sugar syrups, pulp and paper, chemicals, polymers and resins, inorganic salts, acids, bases, and a variety of other materials.

Fruits and Vegetables

Fruit puree( Grapes, apple, cherry)

Grape juice

Lime juice

Pear juice

Pineapple juice

Mango juice

Orange juice

Citrus juices

Blueberry juice

Beetroot juice

Carrot juice

Passion fruit juice

Acerola juice

Coconut juice

Other vegetable juices

Selection of Evaporators

Evaporators chosen all on fruit properties: chemical, rheological and thermal.

The necessary high final concentrations, depend on the type of fruit, degree of ripeness, juice production method, pretreatment and the fiber and pulp proportion.

For most fruit juices, 316 stainless steel is used

Types of Evaporators

Unstirred Open Pan or Kettle

Multi-effect Evaporator: Falling and Rising

Short Tube Vertical Evaporator

Agitated Thin Film Evaporator (ATFE)

Thermally Accelerated Short Time Evaporators (TASTE)

Plate evaporators: Falling Film, Rising/Falling Film, Paravap, Paraflash

Centritherm

Falling Film Long Evaporator (FFLE)

Scraped Surface Evaporator (SSE)

Unstirred Open Pan or Kettle: operating at atmospheric pressure, steam jacketed or heated with closed steam coils and are used for concentration of sauces, jams, and confections products, operating temperatures is 100.8°C

Falling Film Evaporator: largely used for fruit juices.

Plate Evaporators: can be used on a broad range of products, the main application has been with products that are heat sensitive and therefore benefit from the high HTC’s and low residence time.

Rising/Falling Film Plate Evaporator: use in juice processing for product where low residence time and less temperature below 90°C is required.

Falling Film Plate: system with the added benefits of shorter residence time and larger evaporation capabilities, has wide acceptance for heat sensitive products.

Paravap: thin film turbulent evaporator, atomize system provide grater surface area. Finishing evaporator to concentrate materials to high solids. Used for apple puree (70°Brix), Cherry puree (60°Brix) and grapes puree (50°Brix)

Paraflash: suppressed boiling, forced circulation, used for product which subject too high fouling in falling film evaporators. Ex. grape juice etc.

Short Tube-Vertical Evaporator: concentration of sugar cane juice.

Scraped Surface Evaporator: for tomato puree (Highly viscous)

FFLE (Falling Film Long Evaporator): is the current development in the plate evaporator technology. Has a 50% longer flow path. This creates thinner films off the plate, with improved wetting characteristics. The FFLE is current state-of-the art technology, producing concentrates of high quality on a wide range of juices

Centritherm Evaporator: continues to be the evaporator of choice for heat sensitive, viscous and high value products where color, functionality and flavor are important. Pineapple juice concentrates from 12°Brix to 87°Brix, Carrot up to 65°Brix, Blueberries up to 73.5°Brix , Grape juice to 70°Brix and coconut water to 65°Brix. It is used in citrus energy at higher temperature.

Agitated Thin Film Evaporator (ATFE): concentration of orange juice

Thermally Accelerated Short Time Evaporators: high-temperature short-time, multi-effect vacuum tubular evaporators, evaporates 65% solids desired for frozen orange juice

Centritherm

TASTE

ATFE

Reference

APV, Evaporator hand book.

GEA, Evaporation technology for the juice industry.

Karel M. and Lund B. D. (2003), physical principle of food preservation, second edition, chapter;9, concentration, 330-349.

Kerkai H. E. and Mate S. M., manufacturing fruit beverages and concentration, Handbook of fruit and fruit processing, Authors; Sinha N., Sidhu J., Barta O., Wo J., Chapter;13, 215-228.

Sandhu S. K. and Mindas D. K., Orange and citrus juice, Handbook of fruit and fruit processing, Author; Y. H. Hui, Chapter; 19, 309-357.

Skaliotis L., 2012, Beverage application using spinning cone technology. Food marketing and technology, 26-28.

William B. Glover (2004), Selecting evaporators for process applications, Chemical Engineering Progress, 26-33.

Thank You