Food Microbiology

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CHAPTER I
INTRODUCTION

1.1

Background
Food is one of human sources of calorie, protein, fats, and nutrition. Yet,

because of the highly nutritious content, food is susceptible to growth of microorganisms. By the presence of microorganisms in food, the food is more likely to have shorter shelf life. Thus, mostly it is resolved by the addition of antimicrobial substances to food, such as condiments and preservatives. Condiments and preservatives could inhibit the growth of microorganisms or even destroyed them, as they have antimicrobial agents. Some examples of condiments and preservatives are ginger, clove, sodium benzoate, garlic, and coriander. The factors contributing in the effectiveness of condiments and preservatives in inhibiting the growth of microorganisms are the concentration of the antimicrobial, temperature, characteristic of the microorganisms and food, storage time. As different types of microorganisms have different resistance toward the antimicrobial substance, it is important to understand the characteristic of the microorganisms towards the antimicrobial agent. There are two types of resistance: intrinsic resistance and acquired resistance.

There are some methods of observing the capability of the condiments in inhibiting the growth of microorganisms. In the experiment, the method used is well diffusion method, which used different type of condiments and added into holes of agar, where by the inhibition zone by the condiments could be observed. The larger the inhibition zone, the more effective the condiment was in inhibiting the growth of microorganisms.

1.2

Objectives
By conducting the experiment, students are expected to learn and observe

the effectiveness of antimicrobial substance consisted in condiments and potassium sorbate towards the growth of microorganisms.

CHAPTER II
LITERATURE REVIEW

2.1

Antimicrobials
Referring to Volk and Wheeler (1993), antimicrobials are the substances

that are used to inhibit or kill pathogenic or non-pathogenic microbes. Antimicrobials are also often used as sanitizers and preservatives. Sanitizer is an agent to decrease the amount of microorganisms to the acceptable level. It is generally used in food processing equipments. Antimicrobials are grouped into natural antimicrobials and chemical antimicrobials. According to Fardiaz (1992), antimicrobials may be microstatic, which is inhibitory to the growth of microbes, and microcidal, which means able to kill microbes.

Fruit extract is one most susceptible food materials and thus, is often added with preservatives, especially chemical preservatives, stored at low temperature, or pasteurized. Pasteurization is a heating process at 63˚C for thirty minutes. This process is aimed to preserve the stability of the food materials (Buckle et al., 1987).

The growth of microbes can be controlled by using various methods, namely physical method, chemical method, and immunological method. The control of microorganism growth is performed to kill the microbes, to inhibit the microbes, and to destroy the microbes. Physical controls can be performed by sterilization with heating or radiation and filtering. Chemical controls can be carried out by using chemical antimicrobial compounds, such as disinfectants and preservatives. Whereas immunological controls can be performed by vaccination (Batzing, 2002).

2.2

Active Antimicrobial Compounds in Spices

2.2.1 Garlic
Garlic come from the onion family and are an erect biennial herb, which grow annually. It has irregular roots, condensed, flattened step and narrow and has

flat leaves. Garlic’s bulb consists of 6 to 35 bulblets called cloves which enclosed in a thick whitish, glistening, and transparent covering (Anonym1, 2000). According to Ankri and Mirelman (1999), garlic or Allium sativum or lahsoon in Indian name is an edible plant, which has been generating a lot of interest as a medicinal panacea and a cure for a wide variety of different...
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