Problematic Occurrence of Tyrosine Crystals in the Thai Soybean Paste Tao Chieo

Flegel, Timothy W.; Bhumiratana, Amaret; Srisutipruti, A.

doi:10.1128/aem.41.3.746-751.1981

Cited by 13 publications

(7 citation statements)

References 2 publications

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“…The changes of sweet and bitter amino acids also were highest in the lower salt furu. When the content of Tyr is above 2 mg g −1 , Tyr will aggregate and form visible white particle (Flegel et al ., ), leading to its irregular changes during ripening which does result in analytical problems.…”

Section: Resultsmentioning

confidence: 99%

Characteristic of low‐salt solid‐state fermentation of Yunnan oil furu with Mucor racemosus: microbiological, biochemical, structural, textural and sensory properties

Wei

Wang

Liu

et al. 2018

Int J of Food Sci Tech

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The effect of reducing salt on the microflora, enzymatic activity and structural, textural and sensory properties of Yunnan oil furu was studied. Oil furu with different salt content, including 11 (control), 9%, 7% and 5%, were prepared. The results showed that lower salt increased fungus and lactic acid bacteria growth, yielding a tastier product. In addition, pathogenic bacterium such as Staphylococcus aureus and Salmonella were not detected in Yunnan oil furu during low-salt solid-state fermentation, and the Escherichia coli was <3 MPN g À1 . Enzymatic activity decreased slower in low-salt fermented products, leading to more protein hydrolysis. Consequently, the free amino acids and free fatty acids increased significantly. Reduced salt also improved the structural, textural and sensory properties, such as giving a more consistent structure, better spreadability and a better sensory evaluation.Fermentation of Yunnan oil furu with Mucor racemosus G. Wei et al.

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Section: Resultsmentioning

confidence: 99%

Characteristic of low‐salt solid‐state fermentation of Yunnan oil furu with Mucor racemosus: microbiological, biochemical, structural, textural and sensory properties

Wei

Wang

Liu

et al. 2018

Int J of Food Sci Tech

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“…22 They have been found in fermentation products such as soy paste. 23 Perhaps more important, tyrosine crystals have been observed in animal tissues, including those of humans under pathological circumstances. They are seen in the urine of patients with liver damage, 24 and those suffering from one of the three forms of genetic tyrosinemia.…”

Section: ■ Discussionmentioning

confidence: 99%

Tyrosine Microcrystals Produced by Digestion of Proteins with Pancreatic Enzymes

McPherson

Larson

Kuznetsov

2012

Crystal Growth & Design

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If serum albumin from several animals, including humans, at concentrations greater than about 60 mg/mL is combined with an aqueous extract of porcine or human pancreas, then massive amounts of microcrystals develop. Both raw blood serum, as well as a range of concentrated, pure proteins, when combined with the extract produced identical crystals. Morphologies of crystals and their aggregates did, however, show some dependence on the starting protein material. Crystals could be dissolved by boiling in water and recrystallized. By X-ray diffraction we showed the crystals to be l-tyrosine crystals, presumably a degradation product of the starting proteins. Amino acid analysis, supported by mass spectrometry, of even well washed crystals, however, consistently showed them to be composed of 20% to 30% of other amino acids. An atomic force microscopy investigation of the crystals revealed that the crystal surfaces were persistently coated with spherical particles about 3 nm in diameter. The particles are apparently micellar arrangements of oligopeptides. Some implications of our results with regard the appearance of tyrosine crystals in human tissues under pathological conditions, in tumors, and in natural products such as foods are discussed.

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“…This will reduce the consumers' confidence toward the product and damage the corporate brand, thus causing economic losses. This phenomena is not only observed in broad bean paste, but also exists in Thai style Tao chieo (Flegel, Bhumiratana, & Srisutipruti, 1981), salted bovine sausages (Kröckel, Schmidt, & Andrée, 2016) and other fermented foods (Ferng & Chiou, 1993). The main component of the water insoluble components is tyrosine which is formed as a result of proteolytic enzyme activity (Kröckel et al, 2016).…”

Section: Introductionmentioning

confidence: 93%

“…To further lower the possibility of tyrosine crystals in the product, process optimization was another effective method to reduce the tyrosine content since the production of the proteolytic enzymes by A. oryzae was influenced by the surrounding environment. In Thai soybean paste production, changing its production process could exclusively remove the undesired tyrosine particles (Flegel et al, ).…”

Section: Introductionmentioning

confidence: 99%

Adaptive evolution of Aspergillus oryzae 3.042 strain and process optimization to reduce the formation of tyrosine crystals in broad bean paste

et al. 2018

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Tyrosine crystals occasionally appeared on the broad bean paste surface, which will cause economic losses. This study aimed to eliminate the tyrosine crystals in broad bean paste through decreasing the activities of proteolytic enzymes produced by Aspergillus oryzae and process optimization. Broad bean pastes containing no more than 6.16 mg/g dry material tyrosine showed low possibility to form tyrosine crystals. Using tyrosine as substrate, the A. oryzae 3.042 was adaptively evolved and the tyrosine content in the broad bean paste fermented by the evolved A. oryzae was reduced from 6.49 mg/g dry material to 6.14 mg/g dry material (p < 0.05). When the production process was optimized, the tyrosine content in broad bean paste was further reduced to 5.67 mg/g dry material (p < 0.05). In this condition, no tyrosine crystals were formed in broad bean paste after the 12‐month storage while the product quality was not influenced. Practical applications Tyrosine crystals were one of the most important factors which negatively influence the quality of traditionally fermented food, including broad bean paste, soybean paste, and sausages. The appearance of tyrosine crystals in these foods will cause economic losses to manufacturers. This study tried to eliminate the appearance of tyrosine crystals through decreasing the activities of proteolytic enzymes produced by Aspergillus oryzae 3.042 and fermentation process optimization. The adoption of modified A. oryzae and optimized fermentation process successfully guaranteed the elimination of tyrosine crystals formation in the production and storage period of broad bean paste. This will not only benefit the broad bean paste manufacturers but also provide guidance for other fermented food producers to deal with tyrosine crystals problem.

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Problematic Occurrence of Tyrosine Crystals in the Thai Soybean Paste Tao Chieo

Cited by 13 publications

References 2 publications

Characteristic of low‐salt solid‐state fermentation of Yunnan oil furu with Mucor racemosus: microbiological, biochemical, structural, textural and sensory properties

Characteristic of low‐salt solid‐state fermentation of Yunnan oil furu with Mucor racemosus: microbiological, biochemical, structural, textural and sensory properties

Tyrosine Microcrystals Produced by Digestion of Proteins with Pancreatic Enzymes

Adaptive evolution of Aspergillus oryzae 3.042 strain and process optimization to reduce the formation of tyrosine crystals in broad bean paste

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