Food Processing & Preservation )SFS 2094)Experiment 1Dr. Ruzaina bt Ishak012014051156INTRODUCTION

In food preparation, curing refers to various preservation and flavoring processes, especially of meat or fish, by the addition of a combination of salt, sugar and either nitrate or nitrite. Many curing processes also involve smoking. The etymology of the term is unclear, but it is thought to derive from the same Latin cura, -ae, from which the other English meanings are also derived

Curing with salt and sugar may be called salting, salt-curing, sugar-curing or honey-curing. The application of pellets of salt, called corns, is often called corning. Curing in a water solution or brine is called wet-curing or pickling or brining. Paul Bertolli notes that a pickle contains nitrite in addition to salt. (Bertolli 2003) The curing of fish is sometimes called kippering (Malabarsuperspice 2006)

MATERIALSEquipments

1. 2 Beakers2. Electronic balance3. Pairing knife4. Plastic cover5. Water bathMaterial1. Sodium Nitrite2. 54grams of meat (2x54g)

PROCEDURE

The fresh meat of 650grams in total sum was divided into 12 groups. Each group was given two of 54grams of meat.1. One part of the 54grams of meat was put into a plastic and mixed with 0.015gram of sodium nitrite. It was rubbed for 3minutes. 2. Then, the meats were then placed into two beakers respectively and tightly. They were labeled as Control and Treatment whereby Control is the meat bear meat as it is and Treatment is treated with sodium nitrite.3. Surface colour of the meats was observed. With the use of pairing knife, both meats were cut to expose the interior, the interior colour was observed.4. Both samples were refrigerated for 26 hours. (starting from 10am till the next 12noon).5. Then, both of the samples were taken out and subjected to water bath for 15 to 20 minutes andstep 4 was repeated.

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Figure 1 : The first at most left is the Control meat sample and next to it is Treatment Meat sample

Colour

Control (no nitrate)Experimental with nitrate

TimeSurface InteriorSurfaceInterior

Before StoragePurple Red

Purple Red

Brown

Purple Red

After StoragePurple Red

Purple Red

Brown

Purple Red

After CookingGreyish Purple Red

Greyish Purple Red

Grey

Grey

Table 1 : Observation of Meat Sample with and without Sodium Nitrate

DISCUSSION

In this experiment, we had conducted an experiment under the laboratory topic of Role of salt in processing. To demonstrate its application in hands on practical, we had learnt to execute the Curing method towards the meat sample. The objective of this experiment was to identify the colour of the meat samples with and without the presence of sodium nitrate, before and after refrigeration (storage), and also before and after contact with heat (water bath).

At the beginning of the experiment, the Control sample showed purple red colour for both surface and interior part of the meat. In contrast to the Treatment sample, it transformed into brown colour at the surface but remained purple red in its interior part. The nitrite, when added to water forms nitrous acid and nitric oxide, and which penetrate the meat and combine with the myoglobin to form nitric oxide myoglobin. This pigment is not stable until after cooking, But, as initial phase, the myoglobin was converted into oxymyoglobin(red before storage, without sodium nitrate) then into metmyoglobin (brown colour) (IFT 2009)After storage, the Control became purple red on the surface and interior part, it remained the same. Under Treatment sample, it turned into brown for the surface and purple red for interior part. After cooking, both of the Controls surface and interior was greyish purple red and Treatment was both grey. According to the literature review, this indicates that the meat was cured by only sodium and not with nitrite. The presence of nitrite/nitrates should have preserved the light pink colour of the meat especially after heating. The result was halted only till denatured myoglobin and did not proceed to nitrosylhemochrome (with nitrite/nitrate) (Boles & Pegg 2007)

CONCLUSION

In a nutshell, the experiment has achieved the objective of the experiment in which to study the effect of the colour of the meat samples with and without the presence of sodium nitrate, before and after refrigeration (storage), and also before and after contact with heat (water bath). But sadly, our groups end result for the water bath step different from that of the literature reviews theory and experiment. The result that we had obtained for the end result was opposite of the expected result. Our recommendation in order to improve the lab session is too follow the exact materials as stated in the laboratory manual. The original instruction is the we should have used sodium nitrite instead of sodium nitrate.

REFERENCE

MalabaSuperSpice. 2006 .Understanding Cured Meats .Retrieved from 2015, 23rd June from :- http://www.scienceofcooking.com/curing_foods.htm

Institute of Food Technologies (IFT) .2009 .Meat Pigment Chemistry .Retrieved from 2015, 23rd Junefrom:http://www.ift.org/~/media/Knowledge%20Center/Learn%20Food%20Science/Mini%20Experiments/CuredMeatPigment.pdf

Boles, J.A. & Pegg, R. 2007 .Meat Colour.Retrieved from 2015, 23rd June http://www.cfs.purdue.edu/FN/fn453/meat%20color.pdf

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