Post Mortem Factors That Affect Toughness or Tenderness of Meat

The most important factors affecting tenderness are cooking methods and heat.

The heat of cooking affects tenderness in two ways:

• Heat tenderizes connective tissue if moisture is present and cooking is slow.
• It toughens protein. Meat can turns tough and dry if cooked at excessively high heat for too long.

(Wayne Gisslen , 2004)

Because high heat toughen and shrinks protein and causes excessive moisture loss, low heat cooking should be the general practice. Among the cooking method preferred are low heat roasting, broiling and simmering. For this reason, our experiment is done by frying at 150 degree Celsius.

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Rigor Mortis

To know how muscle turns into meat, we must first understand what is rigor mortis.

When an animal dies, aerobic glycolysis stops since no oxygen is available. As the muscle attempts to maintain homeostasis, muscle glycogen is metabolised via anaerobic glycolysis, thus phosphorylating ADP to supply ATP.

Anaerobic glycolysis generates lactate that accumulates, lowering the intracellular pH, so that by 24 hours post mortem the pH has fallen to an ultimate pH of about 5.4–5.7.
Muscle is highly sensitive to both ATP and Ca2+, which are both involved in the contraction–relaxation process. Consequently, as ATP levels are reduced and Ca2+ levels rise, irreversible cross bridges form between myosin head and actin. This formation is associated with an increase in toughness.
It was also reported that meat with low ph is likely to be poorer eating quality as the enzymes involved in post mortem tenderization are inhibited by the acidification. (Maltin et al, 2003)

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Juiciness of meat

The Juiciness Factor

Juiciness is a very subjective measurement. One person’s definition of juiciness may differ from the other.

Three main factors affect the perception of juiciness:

- Internal fat – Fat makes meat juicy and we all know that. Lean meat taste drier and lack succulent than of marbled meat.

- Gelatin – Converted from connective tissue in muscle, it readily binds to water molecule and holds them in meat.

- Protein coagulation – as mentioned earlier, protein coagulates when cooked and looses water. The more it is cooked, the more it contracts and forces out the moisture. Also, extreme pH may cause protein coagulation too, which we will see later in our discussion of results ( Wayne Gisslen , 2004)

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Ingredients

1 x 500mL tub of yogurt








300gm Ritz crackers





Corn oil




corn flour

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Production of chicken nuggets -- Day 1

1) Wash chicken breasts thoroughly with running water to remove any unwanted material

2) Put the chicken breasts one at a time into a freezer bag so that they lie flat

3) Bash with a roller pin until the chicken is quite thin

4) Take it out and slide into few slices and repeat with other chicken breast.

5) Separate the chicken slices into 3 parts
The 1st part - chicken slices, unmarinated into freezer bag(control)
The 2nd part - chicken slices with water into freezer bag
The 3rd part - chicken slices with yogurt

6) Store all the 3 bags of chicken slices into chiller for one day

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Production of chicken nuggets-- Day 2

1) After marinating for 24 hours, the chickens are ready to be fried. Fill the deep fryer with oil and heat the oil in a deep fryer at 150°C.

2) Put the Ritz crackers into a bag, seal the end, then bash and roll them with a rolling pin until they have broken down into little pieces

3) Placed the crushed biscuits into a wide shallow bowl

4) For chicken soaked and none soaked with water, coat them with corn flour before frying so crackers can adhere to chicken

5) For chicken soaked with yogurt, shake off the excess yogurt from the chicken slice and dip them into the crumbs. Coat them well before laying gently into the hot oil

6) Cook til the surface of the chicken turns golden brown in a deep fryer

7) Transfer them to kitchen towel to blot the excess oil

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Sensory Analysis

Acceptance testing was chosen because this is the most suitable feedback format to be used to measure the degree of likeliness of individual products. In our feedback format, Hedonic Scaling is used. Hedonic 9-point scaling format is considered the most sensitive or facial scaling. The data will be summarized using histogram.

Consumer testing is carried out to assess the acceptability or preferences for the product. It is divided into 2 categories- large, untrained, subjective consumer panel and intermediate subjective panel. The panel we chosen are from large, untrained, subjective consumer panel.

Therefore, random 20 classmates were chosen which consist of 5 males and 15 females age ranged from 20 to 22 years old.

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