Theory Behind (Discussion)

Peoples always said that bath with milk can make their skin become fairer, softer and also provide a lots of vitamins like A and D in improving their skin complexion. Nevertheless, it also can be used in improving the texture of calamari rings that we used to eat.

3 bowls of calamari rings are prepared and each of them undergoes the following processing method:-

Bowl 1 - Without soaking in milk
Bowl 2 - Soaked in sour milk for 3 hours
Bowl 3 - Soaked in fresh milk for 12 hours

After all the calamari rings are being fried, the results are as following:-

Bowl 1 - Rubbery and toughening texture with strong fishy smell
Bowl 2 - High tenderness and juiciness in texture and without fishy smell
Bowl 3 - Mild tenderness and juiciness in texture if compared to calamari rings in bowl 2 and without fishy smell

• Squid contains 75-84% of water, 13-22% of crude protein (including the myofibrillar protein), 0.1-2.7% of lipids and 0.9-1.9% minerals.

• Tough and rubbery calamari rings are due to the effect of heat denaturation of the myofibrillar proteins and the high level of moisture loss during prolonged cooking.
  
  
• Mantle part of squid is cut before transformed into calamari rings. The purpose is to remove the intermolecular cross-links and also increase the surface area which helps the lactic acid in the milk to penetrate and act onto the calamari rings.
  
  
• During marinating treatment of connective tissue with lactic acid in sour milk, it changes the physico-chemical properties of collagen and hydrolyzed the non-collagen proteins. These causes the solubilizations of collagen in calamari rings to the sour milk and thus improve the degradation process of the muscle fiber in calamari rings and leads to the effect of tenderization of calamari rings.
  
  
• Factor like the amount of collagen in the squid mantles leads to different level of improved tenderness as collagen varies with squid species which is presumable responsible for the tough texture. (Eg, Mantle of Mex species contains 11.1% of collagen whereas the mantle of Loligo species contains only 3.0% of collagen)
  
  
• Lactic acid in milk played an important role for the improved juiciness and tenderness in calamari rings during the marinating. Marinating in acidic solutions such as the sour milk (sour milk is made by adding one tablespoon of vinegar to a cup of whole milk, mix and let it stand for 5 mins) being used in this experiment contain higher amount of lactic acid (0.12% to 0.20%) had decreases the mechanical resistance of the calamari rings.
  
  
• This treatment is a combination of weakening or degrading of the myofibrillar structure of high connective tissue content to a lesser extent. Furthermore, it also increased the water-holding capacity in calamari rings which can be observed from their swelling appearance as the reason behind of improved juiciness. Increased water-holding capacity solves the problem of easily fallen coating of calamari as for the crispiness on the outer part.
  
  
• Better tenderness and juiciness in calamari rings in bowl 2 compare bowl 3 is because the content of lactic acid in sour milk is higher than in flesh milk which contains approximately only 0.002% (about 2 parts per 100,000) lactic acid.
  
  
• Lactose is the main substrate for LAB (lactic acid bacteria) in producing lactic acid in fresh milk. In other words, lactose and the amount of LAB of the fresh milk are the two main factors for the lactic acid content in fresh milk in marinating the calamari rings.
  
  
• Questions might be raised as the existence of LAB inside the fresh milk since the most milk sold in the markets were undergoes heat treatments such as pasteurization, sterilization and ultra heat treatment for safe consumption and extend the shelf life of the products. The milk that used in bowl 3 is pasteurized milk. Milk usually are pasteurized at the temperature of not less that 71.7C for at least 15 seconds (max is 25 seconds).
  
  
• Research had shown that acid-forming bacteria such as LAB are still surviving in the pasteurized milk and this is the results why pasteurized milk are sour normally even before the expired date stated.