NESCO® Vacuum Sealers will change the way you purchase and store foods. As you become accustomed to vacuum packing, it will become an indispensable part of your food preparation. When preparing and vacuum packing foods using your Vacuum Sealer, there are certain procedures that must be followed to ensure food quality and safety. Review this section carefully for your protection.
• Food spoilage is caused by chemical reactions in the food to air, temperature, moisture, enzyme action, growth of micro-organisms, or contamination from insects.
• Oxygen in the air causes spoilage primarily through the process of oxidation, which causes food to lose nutritive value, texture, flavor and overall quality. Air contributes to the growth of most micro-organisms, and carries moisture into and out of foods unless they are protected with moisture-proof packaging. Freezer burn results from frozen foods being exposed to air.
• Vacuum packaging with the Vacuum Sealer removes up to 90% of the air from the package. In scientific terms, the vacuum level is measured up to 24” Hg (inches of Mercury). Air contains approximately 21% oxygen, which leaves a 2% to 3% residual oxygen level in vacuum packaged foods. Most mold, moisture and micro-organisms are inhibited from growth when the oxygen level is at or below 5%.
• Although vacuum packaging extends the life of many fresh foods by reducing oxidation, most fresh foods still contain enough moisture to support the growth of micro-organisms which can grow with or without air. To prevent spoilage, foods need to be stored at low temperatures.
• Temperatures in the refrigerator greater than 40°F (4°C) (especially for extended periods of time) may support the growth of harmful micro-organisms. Monitor the temperature and maintain a temperature at 40°F (4°C) or below.
• Suitable temperature for the freezer is 0°F (-17°C). Freezing retards the growth of microorganisms, BUT DOES NOT KILL THEM.
• Dried foods are also affected by storage temperature when vacuum packaged. Their shelf life is extended 3-4 times for every 18° F (10°C) drop in temperature.
• Micro-organisms can be divided into three categories: mold, yeast, and bacteria. Although micro-organisms are present everywhere, they can only cause problems under certain conditions.
• Mold does not grow in a low oxygen environment or in the absence of moisture. Yeast requires moisture, sugar and a moderate temperature to grow, but can grow with or without air. Refrigeration slows the growth of yeast and freezing stops it completely. Bacteria can grow with or without air.
• Clostridium botulinum is an extremely dangerous type of bacteria, which can grow under the right conditions without air. Botulinum organisms grow in the temperature range of 40° to 115°F (4° to 46°C). Conditions for growth are foods lacking acid, low oxygen environment and temperatures greater than 40°F (4°C) for extended time.
• Foods that are resistant to botulinum are frozen, dried, high in acid, salt or sugar. Foods susceptible to botulinum are non-acid foods which include meats, poultry, fish, seafood, lye-cured olives, eggs and mushrooms; low-acid foods are mostly vegetables; medium-acid foods include overripe tomatoes, onions, chili peppers, figs and cucumbers.
• The foods most susceptible to botulinum should be refrigerated for short term and frozen for long term storage. Consume immediately after heating.
• Warning: Do not heat low-acid vacuum packed foods in the vacuum sealer bags unless you are going to eat them immediately. Foods that are vacuum packed, heated, then left out at room temperature while still sealed in the vacuum are subject to micro-organisms which may be harmful if consumed.
• Enzymes occur in foods and cause increasing changes in color, texture and flavor as foods mature. To stop enzyme action, vegetables must be blanched by heat, either in the microwave or with steam. Note: Heat all the way through briefly so vegetables are still crisp. Foods that are high in acid (such as most fruits), do not need to be blanched.
• Insect larvae are frequently present on many dried foods. Without vacuum packaging or freezing, they may hatch during storage and contaminate the foods. Some products such as flour and cereals may also contain larvae. Vacuum sealed packaging prevents weevils and other insects from hatching because they cannot live without air.