Scraped surface heat exchangers

Scraped surface heat exchangers are used for processes likely to result in the substantial deposition of suspended solids on the heat transfer surface. In has been used for many years, and still are used, in aseptic processing systems to heat and cool products.

In principle, a scraped surface heat exchanger is a monotube equipped with a rotating internal scraper. The scraper keeps the heating surface free from any deposits and also promotes turbulence.

Scraped surface heat exchangers can be employed in the continuous, closed processing virtually any pumpable fluid involving cooking, slush freezing, cooling, crystallizing, mixing, plasticizing, gelling, polymerizing heating, aseptic processing, etc.

Use of a scraped surface heat exchanger prevents the accumulation of significant buildup of solid deposits. Unlike tubes that usually operate with water as medium, scrape surface heat exchangers tend to use steam for greater heat transfer efficiency.

Due to the mechanical construction and the moving parts, scraped surface heat exchangers are more expensive than any other heat exchanger use in food processing. They can be justified only for heating/cooling fluid foods that cannot be handled in normal tube or plate heat exchangers.
Scraped surface heat exchangers

Food packaging development

Food packaging industry has become a giant sector in the food industry. Packaging has become an integral part of the processing, preservation, marketing and even the cooking of foods.

Packaging offers the food industry a marketing tool that is moist useful in the growth and promotion of sales. In principle, the product and its package are an integrated unit. The properties of one determine the properties of the other.

Packaging has become a high tech; it is no longer just a box or a  bag that gets a product into a supermarket and then home onto a consumer’s shelf.

Initially, packages served simply to contain products and to protect them from outside contamination. However, there has been tremendous growth in the development and design of new packages to fit specific needs.

While there has been adaptation of many of the traditional packaging materials, e.g paper, glass, and metals (tin, steel, and aluminum), much of the growth has been due to development of plastic or flexible packaging materials.

Technology advances definitely have played a part, for without many of these developments – such as plastic soda and ketchup bottles and microwave containers - none of these new products and packages would have been available.

Improvements in raw materials also have occurred and many packages that were on shelves several years ago have been replaced by better, lighter-weight, and cleaner containers.

The plastic segment of the packaging industry has shown the most rapid growth for many reasons. Some of the most important are:
*Plastics have a wide range of physical and barrier properties
*Plastics offer design capabilities and features not available with other packaging materials
*Some plastics can be used in microwave ovens

Packaging materials may be composed of single component (usually one chemical substance polymeric, building block form) or they may be composed of multiple components, consisting of the variety of materials, usually laminated in layers, offering many advantages not provided by single components.
Food packaging development 

Pretreatment of foods

It is generally necessary for foods to undergo a treatment prior to the canning process, but these pretreatment differ depending on the foods.

The purpose of pretreatment is to help preserve color nutrients, flavor and overall quality.  Specific vegetables and fruits are high in different vitamins. It is important to know how the vitamin is destroyed and what pretreatment will stop the loss.

Some pretreatment are applied to many different foods. One of these, usually applied to vegetables, is blanching. Vegetables may be pretreated before drying, just as they are before freezing, by blanching in boiling water or steam.

Blanching is steam or water is a method of partially cooking the food, typically just to the point of inactivating the enzymes and also used to break the skins of fruits that have a waxy coating.

Steam blanching preserves more of the food’s natural vitamins and minerals than water blanching but requires slightly longer processing period.

Vegetables are first washed, usually in water and detergent, then rinsed. They are then passed over belts, where any remaining foreign matter, such as weeds or stalks, can be removed by hand.

Blanching consists of heat in steam (no pressure) or hot water (usually about 98.9 ° C) until the temperature of the food is brought up to about 82.2 C – 87.8 ° C in all parts, the cooling in water.

Some vegetables cannot be blanched at these high temperatures without adversely affecting their taste and texture. In such cases, catalase is used as the test enzyme for sufficiency of blanch.

Off flavors may result, though even in the absence of catalase, if peroxidase is present.
Pretreatment of foods

Use of food addictive in processing

Food additives play a vital role in today’s bountiful and nutritious food supply. They allow our growing urban population to enjoy a variety of safe, wholesome, tasty foods year round.

Food additives can be used to:
*Improve the taste or appearance of processed food.

*To improve or maintain nutritional value.

*Improve the keeping quality or stability of a food. It is done by adding vitamins and minerals to common foods such as milk, flour, cereal and margarine.

*Enhance flavor or impart desired color.

*Preserve food when this is the most practical way of extending its storage life. It will keep the food appetizing and wholesome. Food addictives retard product spoilage caused by mold, air, bacteria, fungi or yeast.

*To maintain product consistency. Emulsifiers give products such as peanut butter a consistent texture and prevent them from separating. Stabilizers and thickeners give ice cream a smooth, uniform texture.

Use of food additive whether an intentional or incidental one should not be permitted until its safety under conation of the proposed use has been established beyond reasonable doubt as judged by competent experts.  
Use of food addictive in processing