Determination of Sulfur Amino Acids in Milk and Plant Proteins

Johns, Paul W.

doi:10.1007/s12161-020-01854-9

Cited by 7 publications

(3 citation statements)

References 19 publications

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“…Sulfur-containing amino acids are the first limiting amino acid in various dietary proteins including casein ( 39 ), which supports the obtained results of amino acid content ( Table 3 ). Methionine, which is the main source of sulfur content ( 40 ), was increased from 0.71 mg/g in SM to 0.89 mg/g in NCP ( Table 3 ). This was reflected in a significant increase in sulfur content from 304.78 ppm in SM to 313.77 ppm in NCP.…”

Section: Resultsmentioning

confidence: 99%

Nano casein–pectin complex: exploring physicochemical, organoleptic properties, and LAB viability in skimmed milk and low-fat yoghurt

Gomaa,

Allam,

Mokhtar

et al. 2024

Front. Nutr.

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Protein complexes with a nutritional value, heat stability, and gelling properties with no negative impact on culture viability have promising application prospects in the fermentation industry. The aim of the study was to investigate the possibility of applying physical modification seeking high-protein-fortified yoghurt production using the nano casein–pectin NCP complex as an active colloidal system with enhanced structural and thermal properties and monitor the quality properties of the physicochemical, heat stability, rheological, starter culture viability and sensory evaluation of fortified products comparing with the plain control throughout the cold storage. High-energy ball milling (HEBM) technique was used to produce nanoparticles of casein powder and smaller particles of pectin individually, and particle size and zeta potential was assessed. Deferent Nano casein-pectin (NCP) complex formulations were prepared, their physicochemical properties were assessed including protein quality via Amino Acid Analyzer (AAA), viscosity, thermogravimetric analysis (TGA), and then used in fortification of skimmed milk and low-fat yoghurt to monitor the fortification effects. The particle sizes showed to be ≈166 nm and 602.6 nm for nano-casein and pectin, respectively. Milk fortification with the NCP complex has significantly increased the nutritional value represented in increased protein content (7.19 g/100 g in NCP5); Ca, P, and S content (2,193.11, 481.21, and 313.77 ppm); and amino acid content with first limiting amino acids; histidine (0.89 mg/g), methionine (0.89 mg/g), and low content of hydrophobic amino acids (HAAs) may cause aggregation. NPC fortification enhanced physicochemical properties announced in enhanced viscosity (62. mP.s in NCP5) and heat stability (up to 200°C) compared with control skimmed milk (SM). NCP yoghurt fortification significantly increased protein content to 11 mg/100 g in T5, enhanced viscosity to 48.44 mP.s in T3, decreased syneresis to 16% in T5, and enhanced LAB viability which was translated in preferable sensorial properties. Applying fortification with nanoparticles of the casein–pectin (NCP) complex balanced the amino acid content and improved physicochemical, rheological, nutritional, and sensorial properties and LAB viability, which can be recommended further in functional food applications.

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Section: Resultsmentioning

confidence: 99%

Nano casein–pectin complex: exploring physicochemical, organoleptic properties, and LAB viability in skimmed milk and low-fat yoghurt

Gomaa,

Allam,

Mokhtar

et al. 2024

Front. Nutr.

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show abstract

“…Experimental assessments of the linearity, precision, accuracy and selectivity associated with the HPLC/UV determination of total Met, cystine and Tyr were performed and documented previously (Johns, 2020). Standard curve coefficient of determination (R 2 ) exceeded 0.999 for all analytes, day-to-day relative standard deviation (RSD) was <3% for all analytes, and a spike recovery of 101% was measured for Lcystine known addition experimentation.…”

Section: Methods Validationmentioning

confidence: 99%

“…HPLC/UV determinations of total Met, cystine and Tyr were performed as described elsewhere (Johns, 2020). Briefly, either 1.00 mL of a 3.00% (w/w) solution of casein hydrolysate in Milli-Q Plus water or 0.150 mL of a 20.0% (w/w) solution of casein hydrolysate in Milli-Q Plus water was weighed into a tared 20-mL glass ampoule (Kimble P/N 12010 L 20).…”

Section: Determination Of Total Met Cystine and Tyrmentioning

confidence: 99%

Pink colour formation in hydrolysed casein

Johns

2021

Int J of Food Sci Tech

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Pink discolouration in a casein hydrolysate prompted an investigation into its formation. When an aqueous solution of the hydrolysate was held at 110°C, an intense red colour was generated, as was a strong sulphide odour. In a study of colour and amino acids in a hydrolysate solution held at 110°C for 0-11 h, a substantial cystine loss occurred, with which colour formation was correlated. The red material exhibited affinity for an anion exchange resin, and its analysis by HPLC found ≥7 apparent pigment compounds. These characteristics, along with the free amino acids in the hydrolysate, seem consistent with the formation of thiosulphinate-derived, conjugated, carboxylated and pyrrole-based pigment compounds proposed to explain pinking in processed onions. The data raise the possibility that pathways responsible for pink discolouration in the hydrolysate (and possibly to some instances of pink discolouration observed in cheese) are related to those associated with onion pinking.

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A UHPLC-PDA method for the quantitative analysis of total amino acids in infant formula with microwave-assisted acid hydrolysis

Temtrirath

2022

Chem. Pap.

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Determination of Sulfur Amino Acids in Milk and Plant Proteins

Cited by 7 publications

References 19 publications

Nano casein–pectin complex: exploring physicochemical, organoleptic properties, and LAB viability in skimmed milk and low-fat yoghurt

Nano casein–pectin complex: exploring physicochemical, organoleptic properties, and LAB viability in skimmed milk and low-fat yoghurt

Pink colour formation in hydrolysed casein

A UHPLC-PDA method for the quantitative analysis of total amino acids in infant formula with microwave-assisted acid hydrolysis

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