Packaging of Convenience foods

What are convenience foods?

Convenience foods are used to shorten the time of meal preparation at home.  Some foods can be eaten immediately or after adding water, heating or thawing etc.

Convenience food, or tertiary processed food, is commercially prepared food designed for ease of consumption. Although restaurant meals meet this definition, the term is seldom applied to them. Convenience foods include prepared foods such as ready-to-eat foods, frozen foods such as TV dinners, shelf-stable products and prepared mixes such as cake mix.

Bread, cheese, salted food and other prepared foods have been sold for thousands of years. Other kinds were developed with improvements in food technology. Types of convenience foods can vary by country and geographic region. Some convenience foods have received criticism due to concerns about nutritional content and how its packaging may increase solid waste in landfills. Initiatives have occurred to reduce the unhealthy aspects of commercially produced food and fight childhood obesity.

Convenience food is commercially prepared for ease of consumption. Products designated as convenience food are often sold as hot, ready-to-eat dishes; as room-temperature, shelf-stable products; or as refrigerated or frozen food products that require minimal preparation (typically just heating) Convenience foods have also been described as foods that have been created to "make them more appealing to the consumer." Convenience foods and fast foods are similar, because the development of both occurred to save time in the preparation of food. Both typically cost more money and less time compared to home cooking from scratch.

Types of convenience foods:

Convenience foods can include products such as

Ø  Candy.

Ø  Beverages such as soft drinks, juices and milk.

Ø  Fast food.

Ø  Nuts, fruits and vegetables in fresh or preserved states.

Ø  Processed meats and cheeses.

Ø  Canned products such as soups and pasta dishes.

Ø  Frozen foods.

Ø  Chips and cookies.

Ø  Dehydrated foods etc.,

Candy Packaging:

Prior to the 1900s, candy was commonly sold unwrapped from carts in the street, where it was exposed to dirt and insects. By 1914 there were some machines to wrap gum and stick candies, but this was not the common practice. After the polio outbreak in 1916, unwrapped candies garnered widespread censure because of the dirt and germs. At the time, only upscale candy stores used glass jars. With advancements in technology wax paper was adopted, and foil and cellophane were imported from France by DuPont in 1925. Necco packagers were one of the first companies to package without human touch.

Packaging preserves aroma and flavor and eases shipping and dispensation. Wax paper seals against air, moisture, dust, and germs, while cellophane is valued by packagers for its transparency and resistance to grease, odors and moisture. In addition, it is often resealable. Polyethylene is another form of film sealed with heat, and this material is often used to make bags in bulk packaging. Saran wraps are also common. Aluminum foils wrap chocolate bars and prevent transfer of water vapor, while being lightweight, non-toxic and odor proof. Vegetable parchment lines boxes of high-quality confections like gourmet chocolates. Cardboard cartons are less common, though they offer many options concerning thickness and movement of water and oil.

Packages are often sealed with a starch-based adhesive derived from tapioca, potato, wheat, sago, or sweet potato. Occasionally, glues are made from the bones and skin of cattle and hogs for a stronger and more flexible product, but this is not as common because of the expense.

Beverages Packaging:

The packaging requirements for all types of beverages are:

• Absolutely leak-proof and prevent contamination

• Protect the contents against chemical deterioration

• No pick up of external flavours

• Be hygienic and safe

• Retain carbonation in the case of carbonated beverages

• Economical, easy to use and dispose

• Good aesthetic appearance

Beverages are classified into Alcoholic and Non-Alcoholic beverages.

Packaging Materials for Non-Alcoholic Beverages:

Key parameters to be considered when selecting a packaging system are:

• Process

• Distribution, shelf-life requirements, legislation

• Product composition and quality as produced and at full shelf-life

• Product protection required during storage, distribution and retail sale

• Pack size, printing options, display etc.

• Packing system concept, automation options, ability to integrate with existing and/or future systems

• Consumer appeal, image of product and packing

The different packaging materials used are:

• Glass Containers: The use of glass bottles for the packaging of fruit beverages was widespread although the hot-fill/hold/cool process had to be applied with care to avoid breakage of the containers. Glass is still the preferred packaging medium for high quality fruit beverages. However, over recent years, an increasing proportion is being packed aseptically, into cartons.

The improvements that have occurred in glass bottle packaging are:

• Light weight

• Surface coating to increase abrasion resistance

• Use of wide mouth containers fitted with easy-open-caps.

• Metal Containers: Tinplate cans made of low carbon mild steel of 99.75% purity, coated with tin with easy open ends are used. These tinplate containers are either 3 piece or 2 piece containers. They are lacquered internally to prevent corrosion.

• Plastic Containers: Fruit juices contain organic substances, which are sensitive to bacterial contamination. Packaging of such products is done through hot filling, to achieve extended shelf-life, PET bottles are usually used for hot filling applications. Special features are added to the containers through design and manufacturing process. The package is heat-set in order to improve the temperature resistance of the containers. PET resins with a higher Tg (glass transition) temperature and/or a faster rate of crystallisation are used. Normally hot-filled PET bottles are designed about 1.5 times heavier than cold-filled bottles. Reinforcing ribs and grooves are also provided along the circumference and base of the bottle. After filling and capping operations, the liquid continues to cool, which results in formation of vacuum. The bottle wall can deform under the influence of vacuum, and this problem is overcome by providing vacuum panels in the container side wall. Generally, lower levels of PET co-polymer are preferred and intrinsic viscosities of about 80 are acceptable. Flexible plastic packages offer economic savings over conventional glass and metal containers but they are permeable to oxygen. Therefore, it is critical to select a flexible package that minimizes the permeability to oxygen. Flexible laminated pouches like metalized polyester/polyester/ polyethylene are used for hot fill packaging method without retorting for acidic fruit juices. These are used either as flat pouches or stand-up pouches. However, the shelf-life of the product in these pouches is limited.

• Aseptic Packages: Ready to serve fruit beverages and fruit pulps / concentrates, packed in aseptic packages provide excellent protection for fruit juices / pulps. These aseptic packages are made by combining thermoplastic with paperboard and aluminium foil. Their multi-layered construction enables the carton to protect the contents from various factors responsible for spoilage. The aluminium foil layer is a strong barrier for O2 and light. The inner plastic layer made of polyethylene makes it possible to seal through the liquid. The outer paper layer provides stiffness making it possible for the cartons in a brick shape, thus, enabling maximum utilization of available storage and transportation space. Excellent graphics are possible leading to good display and shelf appeal and also providing information regarding the product. The aseptic process makes the product bacteria-free before being packaged. To provide convenient access to the contents, beverage cartons offer a variety of opening devices. A familiar opening feature of the pack is the drinking straw, which is attached to the package. Some recent trends are pull-tab opening, which can be readily detached from a pre-punched hole without compromising the package integrity. Also, custom designed caps and closures can be incorporated on beverage cartons for easier pouring and for enhancing the brand image. Also, the beverage cartons are now available in new prisma shape, which is comfortable to hold, and the unique shape offers maximum display effectiveness and high space efficiency. These packs are shelf-stable at room temperature and the shelf-life and nutrient composition of the fruit juice is influenced by the barrier properties of the tetrapak.

• Bag-in-Box System: It consists of a collapsible bag within a rigid container, a filling machine to introduce the liquid product into the bag and a dispenser to draw the product out.

Bag: The outer container can be a box, a crate or a drum. The bag actually consists of two bags. An inner bag contains the liquid and an outer bag provides the barrier properties. Both are heat-sealed at the edges. The tubular spout fitted to the bag aids in filling and dispensing of the product. As little as 3 litres or as much as 1000 litres, can be packed.

The bag is the “life” of the system. The bag itself consists of three components:

i. An inner layer

ii. An outer layer

iii. A spout

The function of the inner layer, the one in contact with the material being packed, is to provide the bag with seal integrity. The seals are to be strong enough to withstand constant mechanical and chemical “pressure” for at least twice the expected shelf-life of the product.

Generally, the inner layer is not designed for barrier unless the product needs extra barrier, which the outer layer cannot provide. Plastic films manufactured from high performance polyethylene, with excellent sealing and puncture properties are usually used as inner layer materials.

The function of the outer layer is to provide the bag with barrier commensurate with the expectation of the shelf-life of the product. In this respect, bag in box scores over other packaging forms, because unlike other packaging materials like jars and cans, the barrier property and hence the cost of this packaging form can be varied. The shelf-life expectations and storage condition play an important part in determining what the barrier requirements of the outer layer needs to be. The standard outside layer is a metalized film laminate, which under standard conditions has an OTR of 1cc/m2 / 24hrs. The spout and cap assembly are made of injection moulded plastics. The spout is provided with a flange, which is welded to the bag’s inner layer during bag’s manufacture. The spout and cap have two functions. They are used to fill the product in the bag and are also used to dispense the product from the pack. Several spout types are available ranging from a simple bung like configuration to ones, which can only be opened on the filling machine. The caps come with various tamper evident features as well.

Rigid Containers: The purpose of this container, is to hold the bag during storage, transportation and use. As is evident, the bag being made from flexible films, is incapable of being stored and transported by itself. Hence, each bag is individually stored into rigid outer container post filling. For packs of capacity below 50 litres, corrugated fibreboard cartons are generally used as the rigid containers. Beyond that plastics and metal drums are used. For very large bags, 1000 litres, + polygonal (6-8 faces) corrugated fibreboard containers made from 7 to 9 ply are used, though there are other alternatives as well.

Ex) Coffee

While developing packaging system for coffee the following are to be considered:

• Moisture vapour ingress

• Oxygen permeability

• CO2 and Volatile component egress

• Grease resistance

The packaging materials used are tinplate containers, composite containers, glass jars and flexible plastic pouches. The flexible laminates most widely used are 12μ PET / 2μ Al Foil /

70μ LDPE and MET PET / LDPE. Aluminium foil lined plastic pouches are most popular having 59% contribution in terms of volume.

Carbonated Drinks:

Carbonated drinks contain carbonated water, flavour, colour, sweeteners and preservatives.

CO2 gas from pure source is dissolved in water (amount varies with different types of beverages). A variety of ingredients like flavouring agents, colouring agents, preservatives, artificial sweeteners, antioxidants and foaming agents are then added.

Two major deteriorative changes that occur in carbonated drinks are the loss of carbonation and rancidification of essential flavouring oils. The first is largely a function of the effectiveness of the package in providing a barrier to gas permeation, while the latter can be prevented by the use of high quality flavourings and antioxidants, and de-aerating the mix prior to carbonation. Oxidative rancidity is reduced by the effectiveness of the package in providing a barrier to gas permeation.

Hence, the carbonated drink package requires a container that will hold pressure and not contribute off flavours. For many years virtually all carbonated soft drinks were packaged in glass bottles sealed with crown cork. In recent years, non-returnable glass bottles are giving way to refillable bottles. These have a foam plastic protective label of paper/poly or an all plastic shrink sleeve, as a safety measure to prevent flying of glass fragments in case of breakage of these containers. The crown closure has been replaced with a roll-on aluminium screw cap with tamper proof facility. Among the metal containers, the 3-piece tinplate containers have been used since long for the packaging of carbonated beverages. These are being replaced now by 2-piece aluminium cans. These cans retain the integrity of lacquer better than tin cans. Vinyl, epoxy and vinyl organosol coatings are used as lacquers for aluminium cans. Epoxy amine provides good adhesion, colour and flexibility to the can.

Among the plastic containers, PET bottles are the most preferred packaging material for packaging of soft drinks.

Soft drinks have a maximum permissible level of 20ppm for citrus flavoured beverages and

40ppm for cola drinks while the water loss is of the order of 1%. Also, the loss of CO2 through the wall must be allowed for. While increasing thickness will decrease the rate of CO2 permeation, the cost of the bottle, will also increase and so a compromise has to be made. Other problems to be considered in plastic containers are creep and elastic deformation. The polyethylene terephthalate (PET) bottle satisfies most of the requirements for packaging of carbonated soft drinks.

Improved blow moulding techniques and bi-axial stretching have made PET container to be pressurised due to its strength, dimensional stability and precision. Also, they have a glass like appearance, good transparency, lustre, chemical inertness and unbreakability.

The advantages of PET container are:

• Superior packaging to product ratio: PET container being 63% and 47% more energy efficient than glass bottles and aluminium cans respectively.

• PET bottles are 32% more energy efficient than glass bottles during delivery of 1000 gallons of soft drinks.

• Glass bottles and Aluminium-cans generate 230% and 175% times more atmospheric emissions compared to PET.

• PET bottles contribute 68% and 18% less solid waste by weight compared to glass and aluminium containers.

• 100 kg of oil is required to produce 1000 1-litre PET bottles as against 230 kg for 1000 equivalent glass bottles.

• PET bottles help in fuel saving due to their lower weight.

The resins used in PET bottles to pack carbonated drinks are of a very special quality. The PET bottles have to be extremely strong to contain the internal pressure of CO2 without distortion and expansion. This is obtained by using a resin, which has high intrinsic viscosity and lower co-polymer levels. Currently, more than 90% of PET is consumed in food packaging with beverages/drinks forming nearly 80%.

Packaging Materials for Alcoholic Beverages:

Alcoholic drinks originated through the action of yeast cells on sugar containing liquids. Alcoholic drinks are aromatic liquids with a specified alcohol content. Some kinds contain carbon dioxide, others a quantity of sugar. They are either fruit/sap based or grain based. They can either be non-distilled or distilled depending on the volume percentage of alcohol per litre. The border between the two kinds of drink is about 20%. The different types of alcoholic beverages are beer, wine, whiskey, brandy etc.

Non Distilled Alcoholic Beverages:

• Beer (Grain Based): Beer is made from grains and has low alcoholic content around 5% by volume. Barley is the chief grain, but rice and corn are also used. The grains are brewed and fermented and then carbonated with CO2 and flavoured with hops to give a bitter flavour. Owing to its low pH (about 4.0), microbial degradation is not usually a problem with beer, and the use of pasteurization and aseptic cold filtration excludes yeast. However, during storage beer can undergo irreversible changes leading to appearance of haze, development

of off-flavours and increased colour. The oxidation reaction gives beer a “card-board-like” flavour. Flavour loss is also accelerated in the presence of light and certain metal ions. The fermentation process consumes oxygen. Also, brewing reduces the level of oxygen in beer to 40-50 ppb prior to packaging. During the packaging process, atmospheric oxygen enters the package and the level of oxygen contamination reaches 250-500 ppb, which corresponds to 0.1-0.2 ml of oxygen per 335 ml bottle or can. This results in a shelf-life of beer of 80 to 120 days. The oxygen consumption of beer varies with the composition of the beer, its age, presence of reducing agents, temperature etc.

The traditional packaging media for beer is the glass bottle sealed with a crown closure.

Recent development is the use of PET bottles for packaging of beer. Types of PET beer bottles used are non-tunnel pasterurised, one way tunnel pasterurised and returnable / re-fillable bottles.

Beer needs high performance in both CO2 and O2 barrier compared to PET used in carbonated soft drinks (CSD) applications. The level required depends on the type of beer, container size, distribution channels and environmental conditions (storage time, temperature and humidity levels). Improvements in the barrier can be obtained via colourants, creating multi-layer bottles and scavengers. Protection from U. V. light is obtained by adding colourants or U. V. additives, during the injection moulding stage. Because of the varied requirements for beer, the resins chosen must provide an adequate barrier, UV protection and clarity. Beer bottles need strength in order to maintain the CO2 pressure over a wide range of temperatures. Intrinsic viscosities in the range of 0.8 to 0.84 are normally used.

Since the PET bottles are lighter, a truck can carry 60% more of the beverage and 80% less packaging–a fuel saving of 40% and less air pollution.

• Wine (Fruit/Sap based): Wine is a beverage resulting from the fermentation by yeasts of the juice of grapes with appropriate processing and additions. The major deteriorative reaction in wines is caused by oxidation, the oxygen gradually changing the wine character, leading to development of browning and undesirable flavours. The most common form of packaging used for wines is the glass bottle sealed with natural cork. Since wines are affected by sunlight, the bottles usually used are of coloured glass. Bottled wine is normally stored in the horizontal position so that the cork is kept moist, thereby providing a better barrier to the ingress of oxygen. The most significant change in the packaging of wine resulted from the development of the bag-in-box package: a flexible, collapsible, fully sealed bag made from one or more plies of synthetic films, a closure and a tubular spout through which the contents are filled and dispensed, and a rigid outer box or container. The bag is generally constructed from co-extruded film of EVA-BA-EVOH-BAEVA or LDPE-BA-EVOH-BA-LDPE. The features of the bag-in-box system of packaging have been explained earlier in the chapter.

The physical strength of the bag is of prime importance and must remain intact throughout distribution and subsequent storage. Under normal circumstances, the bags are subjected

to two forms of stress: hydraulic shock (normally caused by sudden acceleration / deacceleration of the pack) and flex crack. By using polymers, which have high flex resistance and improving the adhesion between the films, the strength of the bag can be increased.

One problem associated with the packaging of wine into bag-in-box system is the decrease

in shelf-life as compared to that obtained using traditional glass bottles. This is due to permeation of oxygen through the valve material of the tap. By improving the barrier properties of the bag and the design of the tap the problem can be solved. A special heatsealable membrane is partially attached to the gland during manufacture of the bag. After

filling but prior to insertion of the tap, this membrane is fully sealed to the gland and the

potential entry path is greatly reduced. As a result the bag is completely sealed and is totally independent of the tap until the membrane is broached when the pack is just opened

by the consumer.

Wines are also available in PET bottles and in stand-up pouches of metallised polyester laminates.

Distilled Alcoholic Beverages:

• Brandy and Whisky: These drinks are obtained by distillation of alcohol containing drinks. During distillation the aqueous part is separated from the alcohol. The distillates obtained are sold under several names like brandy, gin, whisky cognac, vodka, etc and have different alcohol percentage. Because of their high alcohol percentages, these liquors are mostly packed in glass bottles so that they can be kept for an infinite time after opening. The bottles are sealed to prevent alcohol from evaporating and to protect the contents of the bottles from dirt and dust.

Packaging system for fruits and vegetables:

Fruits:

Oranges:

Oranges are placed in moulded pulp trays with cavities for individual oranges. Each tray contains about 20/25/30 oranges depending upon the size. Four to five such trays are placed in a corrugated fibreboard box.

Custard Apples:

Custard apples are packed in 3-Ply CFB boxes of RSC type or EPS (Expanded Polystyrene) boxes. The capacity of the box is 3kg. The fruits are placed in one layer inside the box and depending upon the size the number of fruits vary.  The box is closed by application of pressure sensitive tape.

Lychee:

Lychees are graded, weighed and packed in plastic punnets of 250 grams capacity. 8 nos. of punnets are placed in a CFB box (One piece tray type) with ventilation holes. The capacity of the box is about 4kgs. Lychees are also packed in 3-Ply CFB boxes of RSC type of capacity 2 kg. These boxes are then put in cold storage till dispatch. From cold store to airport, the lychee boxes are transported in refrigerated van. For export the transportation is by air.

Vegetables:

Vegetables like green chillies, brinjal, papadi, kantola, tindola, bottle gourd are packed in 3-Ply or 5-Ply CFB boxes with ventilation holes depending upon the capacity. The capacity of box varies from 5kg to 7kg to 10 kg. Generally the box is lidded type (0306) but at times for some vegetables RSC (0201) box is also used. In case of green chillies the different varieties exported are G-4, Kiran and Jawla, while the different varieties of brinjal exported are black beauty, pink rawaya. In case of bottle gourds, they are wrapped in tissue paper and then placed in the CFB box. Tindola are also packed in woven sacks of the capacity of 5 kg to 7 kg.

Vegetables like arbi are packed in capacity of 5kg and yam are packed in  capacity of  10kg to 15kg in gunny bags.

Curry leaves are packed in plastic pouches of 30gm capacity with ventilation holes and then placed in 3-Ply CFB box. The capacity of the box is 3kg. In some cases loose curry leaves are packed in the same box. All the above vegetables are exported by air.

The different varieties of potatoes exported are Kuffri Bahar, Kuffri Locker and Kuffri Badshah. The potatoes are packed in Hessian bags (Jute bags) of the capacity of 25 kg. The bags used are generally hand stitched and the final stitching is done in such a manner that there is no space and scope for the movement of the product within the pack. Two corners of the open end of the bag when stitched are used as handles while loading and  unloading. The potatoes are exported by sea as containerized cargo in both general purpose as well as refer containers. For vegetables like brocolli, celery, Brussels sprout and cherry tomatoes, since the export is negligible, the current packages were not available.

Development of Packages Based on International Standards:

Consumer/bulk packages were developed based on International Standards, making reference to:

1. Manual on the packaging of fresh fruits and vegetables by International Trade Centre, UNCTAD/GATT (1988 edition)

2. Guide to food transport-fruits and vegetables. (Mercentla Publication 1989)

Recommendations are based on UN/ECE and OECD Standards, which are covered in the above publications.

While selecting the packaging materials and packages new type of packaging materials with ability to add value to the product and which is eco- friendly and economic were considered. Some of these are PET punnets with lid, EPS tray stretch wrapped, leno/raschel/net bags and moulded EPS box with lid.

Frozen Foods Packaging:

The prime purpose of packaging of these frozen foods is to keep food from drying out and to preserve nutritive value, flavor, texture and color. Labels on packages will say if the product is suitable for freezer storage.

A good packaging material should have the following characteristics:

·         Moisture/vapor-proof or at least moisture resistant.

·         Made of food grade material, i.e. designed to be used for food products.

·         Durable and leakproof.

·         Doesn’t become brittle and crack at low temperatures.

·         Resistant to oil, grease or water.

·         Protect foods from off flavors and odors.

·         Easy to fill and seal.

·         Easy to mark and store.

The packaging you select will depend on the type of food to be frozen, personal preference and availability. For satisfactory results, do not freeze fruits and vegetables in containers larger than one-half gallon. Packaging not sufficiently moisture/vapor-resistant for long-time freezer storage includes ordinary waxed paper and paper cartons from ice cream and milk.

Rigid Containers:

Rigid containers are made of plastic, glass, aluminum and heavily waxed cardboard and are suitable for all packs. These are often reusable. Straight or tapered sides on rigid containers make it much easier to remove frozen foods.

Glass jars used for freezing should be made for the purpose. Regular glass jars may not withstand the extremes in temperature. Do not use regular, narrow-mouth canning jars for freezing foods packed in liquid. Expansion of the liquid could cause the jar to break at the neck.

Cans, such as shortening and coffee cans, are good for packaging delicate foods. Line the can with a food-storage bag and seal the lid with freezer tape because they are not airtight.

Baking dishes can be used for freezing, heating and serving. Dishes may be covered with a heavy aluminum foil taped with freezer tape. To reuse the baking dish after the food is frozen, wrap the food in casserole- wrap fashion.

Ice cube trays are good for freezing foods in small amounts. Freeze food until firm and then transfer to freezer bags.

Flexible Bags or Wrapping:

Bags and sheets of moisture/vapor-resistant materials and heavy-duty foil are suitable for dry packed vegetables and fruits, meat, fish or poultry. Bags can also be used for liquid packs. Protective cardboard cartons may be used to protect bags and sheets from tearing and to make stacking easier. Laminated papers made of various combinations of paper, metal foil and/or cellophane are suitable for dry packed vegetables and fruits, meats, fish and poultry. Laminated papers are also used as protective overwrap.

Packaging, Sealing and Labeling:

·         Cool all foods and syrup before packing. This speeds up freezing and helps retain natural color, flavor and texture of food.

·         Pack foods in quantities that will be used at one time.

·         Most foods require head space between the packed food and the closure for expansion as the food freezes. Loose packing vegetables, such as asparagus and broccoli, bony pieces of meat, tray-packed foods and breads, do not need head space.

·         Pack foods tightly to cut down on the amount of air in the package.

·         Run a nonmetal utensil, such as a rubber scraper handle, around the inside of the container to eliminate air pockets.

·         When wrapping food, press out as much air as possible and mold the wrapping as close to the food as possible.

·         When packing food in bags, press the air from the bags. Beginning at the bottom of the bag, press firmly moving toward the top of the bag to prevent air from re-entering or force the air out by placing the filled bag in a bowl of cold water taking care that no water enters the bag. Seal either method by twisting and folding back the top of the bag and securing with string, good quality rubber band, strip of coated wire or other sealing device. Many bags may be heat sealed, and some have a tongue-in-groove seal built in.

·         Keep sealing edges free from moisture or food so they will make a good closure.

·         When using tape, it should be freezer tape, designed for use in the freezer. The adhesive remains effective at low temperature.

·         Label each package with name of product, date, amount and any added ingredients. Use freezer tape, freezer marking pens or crayons, or gummed labels made especially for freezer use.

Packaging of dried or de-hydrated foods:

Dried foods are susceptible to insect contamination and moisture reabsorption and must be properly packaged and stored immediately First, cool completely. Warm food causes sweating which could provide enough moisture for mold to grow. Pack foods into clean, dry insect-proof containers as tightly as possible without crushing.

Glass jars, metal cans or boxes with tight fitted lids or moisture-vapor resistant freezer cartons make good containers for storing dried foods. Heavy-duty plastic bags are acceptable, but are not insect and rodent proof. Plastic bags with a 3/8-inch seal are best to keep out moisture. Pack food in amounts that will be used in a recipe. Every time a package is re-opened, the food is exposed to air and moisture that lower the quality of the food.

Fruit that has been sulfured should not touch metal. Place the fruit in a plastic bag before storing it in a metal can. Sulfur fumes will react with the metal and cause color changes in the fruit.