Conservacion Alimentos

FOOD & NUTRITION EUROPE

PRESERVATIVES

PRESERVATIVES

Food & Beverage Preservation: Practical Guidelines
INTRODUCTION
One of today’s challenges for the food industry is to guarantee safe foods throughout the supply chain, whilst retaining the same properties that were present when the foods were freshly made. During the distribution channel, from food manufacturer to consumer, foodproducts need to be protected against physical, chemical and microbial deterioration. This paper focuses on the prevention of food spoilage, caused by the activity of micro-organisms.

MICRO-ORGANISMS
Micro-organisms have many beneficial functions within the food industry. A few examples are yoghurt fermentation by lactobacillus cultures, yeast leavening in bread manufacturing and alcoholproduction by beer and wine yeast. But microorganisms are also responsible for food spoilage and some micro-organisms are pathogenic. In fact the spoilage of the food is caused by the enzymes produced from the micro-organisms, and the removing of the enzymes is achieved most easily by removing the micro-organisms themselves. For growth and multiplication, micro-organisms need organic food (proteins,carbohydrates, fats), a convenient temperature, some moisture, in most cases some air and a suitable pH. Knowledge about the conditions required for growth, will also provide an insight into how to prevent micro-organisms growing and therefore prevent food spoilage. However, whatever other measures are taken regarding preservation, it is clearly essential that food is processed under the highest andmost hygienic conditions in order to minimise the microbial load and minimise any possible contamination.

HURDLE TECHNOLOGY
Hurdle technology means putting up different hurdles or different means of preventing microbial activity and multiplication. Hurdles in the production process (temperature): An increase in temperature leads to increased activity of micro-organisms and enzymes. As a rule ofthumb, for every increase in temperature of 10 °C, the activity increases two times. This rule is true within the temperature range of 0 to 60 °C. At temperatures above 60 °C, micro-organisms and enzymes are destroyed or inactivated. Depending on the temperature / time combination applied (pasteurisation, sterilisation, UHT, HTST), part or all micro-organisms are destroyed and enzymes areinactivated. However, it is important to note that heat-resistant species and spores may survive heat treatments. Decreasing temperatures also reduce the activity of micro-organisms and enzymes. In the refrigerator (4 to 6 °C) and in the freezer (-15 to -20 °C), micro-organisms are less active or completely inactive, but they are not destroyed. Other physical processes such as hydrostatic pressure,irradiation, ultrasound and pulsed electric fields are potential methods for preservation. Hurdles in packaging (air / oxygen) By carefully choosing the packaging material and packaging process (vacuum packaging or modified atmosphere packaging), oxygen as a growth factor can be removed. It should be noted that there are anaerobic micro-organisms which live without oxygen and among these are some foodpathogens. Hurdles in the food composition (pH, Aw, acidulants and preservatives) As stated above, the highest quality ingredients, with as low as possible microbial count, should be used. Furthermore the food composition itself creates a more or less attractive environment for micro-organisms and makes the food more or less susceptible for food spoilage.

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Two very important factors are the presence of water and the acidity level of the food. Water is essential for micro-organisms and therefore drying is an effective method of preservation....