Dry aging pork experiment

Case Study: Dry aging pork above Initial Freezing Point

• Temperature: -1.0℃, above initial freezing point -1.7℃
• Humidity: 80%RH
• Aging time: 35 days

• dry aging process above IFP on day 0

• dry aging process above IFP on day 28

• pH value between 5.8-6.2 is defined as fresh meat, between 6.3-6.6 is defined to sub-fresh meat, and pH above 6.7 is spoiled meat.

• Throughout the entire 35 days IFP dry aging process, the quality of pork loin is mostly preserved in the fresh meat.

• Volatile basic nitrogen (VBN) is a general term referring to the presence of amines and ammonia within the food’s tissue and composition as produced by the activities of microorganisms and enzymes.
• In general, if the VBN value ≦ 15mg/100g is a fresh meat, VBN value between 15 to 25 mg/100g is belonged to sub-fresh meat, if the VBN value is greater than 25mg/100g is a spoiled meat.
• The VBN value was 13.8mg/100g on the day 21 during dry aging process and the VBN value on day 35 was 17.9mg/100g which are all far below the VBN number indicating spoiled meat (25mg/100g).

• IFP dry aging process produce tenderness effects on meat, with time evolution the effect of tenderness is continuously present and penetration force declines within two weeks, in which the penetration force on day 21 and day 35 drops about 30%. This indicates the meat tenderness has undergone significant changes.

• In the process of aging, the protein molecules in the meat will break down into smaller amino acid fragments, including amino acid species which are associated with perceived savoury and delicious-ness. One such amino acid is Glutamic acid, which is the amino acid associated with the savoury umami flavor, is present in the form of monosodium glutamate which in turn is the main compo-nent of sodium glutamate. Therefore,we selected glutamate as a monitoring indicator to observe the changes of glutamic acid contents during IFP dry aging process.
• We found that the glutamic acid content increase significantly during IFP dry aging process that varies by different sample taken locations. The glutamic acid con-tents increase between 13% and 28%, maximum up to 43940ppm, this result provides a scientific evidence that IFP dry aging process can in-crease the delicious taste and umami flavor of meat.
• One more distinguishing characteristic of the IFP dry aging process is that it can induce the develop-ment unique aromas within the food that is not otherwise present in the food before. In this experiment, after 21 days the pork loin began to develop special aromas familiar to milk and cheese. This result is positively striking, as the development of this aroma can only be enabled through IFP dry aging; according to our observations, the aroma development at first was produced from the fat and slowly to the lean muscle parts of the meat, therefore, we can reasonably speculate that the aroma source is the aromatic fatty acid produced by the decomposition of fat after aging.