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Whey proteins were present in appropriate proportion in milk, during heat-treatment at pasteurization temperatures; whey proteins and casein have the ability to form firm gel of uniform porosity through heat-induced protein-protein interactions. In this study, the addition of whey proteins in fresh milk were carry out to investigate whether whey protein would accelerate yoghurt fermentation time and facilitate the yoghurt structure. The results indicated that the addition of whey concentrate 80 increased the water retention capacity of the final product. Whey protein concentrate 80 supplement at the content of 0.8% shortened fermentation time for the product 12.5%. The addition of whey protein also improved the properties of water retention until 26%, viscosity and structure of yoghurt products.

In this study, antimicrobial activity of aminoreductone (AR), a product formed during the initial stage of the Maillard reaction, against methicillin-resistant Staphylococcus aureus (MRSA) was evaluated. The significant growth inhibition of all 51 MRSA isolates irrespective of drug susceptibility by AR was observed. The minimum inhibitory concentration (MIC) of AR ranged from 13 to 26 mM. The bactericidal activity of AR was evaluated by a killing assay with multiples of MIC, and it was recognized to depend on its dose. The combined effects of AR and antibiotics frequently used for the treatment of infections caused by Gram-positive and Gram-negative bacteria, such as amikacin (AN), ciprofloxacin, imipenem and levofloxacin, were examined. As a result, AR did not interfere with these antibiotic activities against 12 MRSA isolates selected and showed the advanced effect of growth inhibition in combination with antibiotics. Moreover, the inhibitory effects of AR were similar to those of AN, an antibiotic with known adverse effects, some serious. These findings show that AR is a naturally formed antimicrobial agent present in thermally processed foods with potential health benefits in medical practice.

The aim of this study was to elucidate the formation mechanism of aminoreductone, an important indicator for estimating the extent of Maillard reaction of lactose and amino compounds. Using the model system of lactose and butylamine, the model solution of lactose and milk proteins, and milks, it was concluded that D -galactose was liberated at the same time as the generation of aminoreductone. It was shown that the extent of the Maillard reaction and the lactose degradation during heating depended closely on the concentration ratio of amino group/lactose in the sample solution.

To create a basis for the production of aminoreductone (AR) followed by the use of it as a functional ingredient in food supplements, the effects of heating temperature, heating time, buffer concentration and reducing sugar/amino compound ratio on the formation of aminoreductone (AR), a product formed during the initial stage of the Maillard reaction,were investigated. In the model solution of lactose (262 mM) and butylamine (1.16 M) in 1.28 M phosphate buffer (pH 7.0), AR formation increased during the prolongation of the heating time at heating temperature less than 100oC. In the heated model solution at 100 oC, the maximum amount of AR was obtained as soon after 10 min of heating time. After that, the decreases of the AR formation was observed by the progress of the advanced reactions of AR. The rates of AR formation increased with the increasing phosphate buffer concentration. Moreover, the increasing in AR formation incorporated in the increase of the butylamine/lactose ratio from 0.1 to 5. Our results might give more insight in the discovery of Maillard reactions in food because it suggested tendency of the AR formation and to control the formation of AR during food processing and model system base on the control of initial constituents and reaction conditions.

Anti-Helicobacter pylori (H. pylori) effects of aminoreductone (AR), a Maillard reaction product, were evaluated in this study. AR effectively inhibited the growth of all 24 strains (19 clinical isolates and 5 isogenic mutants) irrespective of susceptibility to antibiotics and clinical manifestation. The minimum inhibitory concentration (MIC) of AR ranged from 0.5 to 5 mM. A killing assay with multiples of MIC was performed, demonstrating that the killing activity of AR was significantly higher than that of its derived melanoidin, an inhibitor of H. pylori urease-gastric mucin adherence, formed in the final stage of the Maillard reaction. These significant effects of AR on H. pylori were observed even in acidic conditions (pH 3). At most, 25 mM AR effectively exhibited bactericidal activity in all strains. These results rise up the possibility that foods containing AR, such as milk and dairy products, are valuable sources for preventing colonization of H. pylori in the stomach and its associated tissue damages.

The effects of aminoreductone (AR) on photo-degradation of riboflavin were studied for a riboflavin solution (1.5 mg L −1 ) and UHT-treated milk during exposure to irradiation at 7000 lux light intensity for 2.5 h. In riboflavin solution, AR protected riboflavin against degradation under exposure to light, and this ability depended on concentration of AR. In addition, the protective ability of AR was higher than that of ascorbic acid, which has the ability to reduce photo-degradation of riboflavin. The study in milk clarified that heat-treatment of milk enhanced the protective ability against photo-degradation of riboflavin because of generation of AR during the Maillard reaction. In parallel with the decrease of AR concentration in UHT-treated milk by the addition of Cu 2+ , the protective ability correspondingly decreased. Thus, it may be concluded that AR was a principal compound which was responsible for the photo-stability of riboflavin in UHT-treated milk.