Application Research On The Use Of Yeast Extract For Reducing Salt Content In Noodle Products

Salt is one of the most commonly used seasonings that affect the taste and quality of food.However,long-term excessive salt consumption can harm human health,making salt reduction an urgent requirement for the whole society.This study aimed to explore the feasibility of using yeast extracts(YE)for salt reduction in high-salt-containing noodle products.Seven different types of YE were selected,and their taste compounds were determined to investigate their composition and taste characteristics.Subsequently,the effects of YE on dough rheological properties,dough sheets structure,and the edible quality of salt-reduced dried noodles and hot-air dried instant noodles were evaluated at the same addition level to determine the suitable YE types for salt reduction dried noodles and hot-air dried instant noodles.Finally,the YE samples were further separated and purified,and their salty peptide sequences were identified.The salty peptides were then validated using molecular docking technology and sensory evaluation of synthesized peptides.The main results are as follows:(1)The content of taste substances varied significantly among different types of YE and exhibited distinct taste characteristics.YE1 was mainly flavored by oligopeptides,with 57%of the peptides distributed between 180～1000 Da,containing 14% glutathione.The umami free amino acid content was 26.26 mg/g,but the umami nucleotide content was relatively low at 8.07 mg/g,resulting in weak synergistic umami enhancement.YE2 had a high dietary fiber content of 70.35%,with glucans and mannooligosaccharides accounting for 31.20% and36.80%,respectively.Its taste effect was the weakest among the samples.YE3 was mainly flavored by oligopeptides,with 81% of the peptides distributed between 180～1000 Da.However,its umami nucleotide and umami free amino acid contents were relatively low at23.31 and 7.33 mg/g,respectively,resulting in weak synergistic umami enhancement.YE4 and YE7 were mainly flavored by umami nucleotides,oligopeptides,and free amino acids.The umami free amino acid content of YE4 was 65.97 mg/g,and its umami nucleotide content was 83.34 mg/g.The umami free amino acid content of YE7 was the highest at 76.27 mg/g,and its umami nucleotide content was 66.42 mg/g.The oligopeptides with molecular weights between 180～1000 Da accounted for 65% and 55% of YE4 and YE7,respectively.Both showed good synergistic umami enhancement and oligopeptides taste effect.YE5 and YE6 were mainly flavored by umami nucleotides and free amino acids.The umami nucleotide content of YE5 was 164.58 mg/g,and the umami free amino acid content was 47.43 mg/g,but the sodium chloride content was as high as 20.48%.The umami nucleotide content of YE6 was the highest at 283.11 mg/g,and its umami free amino acid content was 62.25 mg/g.Both showed the more significant synergistic umami enhancement,but the distribution of peptide molecular weights was uneven,with the proportion of peptides below 180 Da being relatively high at 82% and 87%,respectively.(2)YE improved the sensory quality of salt-reduced dried noodles and hot air-dried instant noodles,enhancing their saltiness and flavor,with YE4 and YE7 showing significant improvement effect.However,YE disrupted the disulfide bonds between gluten protein molecules,weakening the gluten network structure.At an addition level of 1%,all types of YE increased the dough’s water absorption rate and degree of softening,decreased its stability time,lowered its extensibility,decreased the peak viscosity of wheat flour paste,increased the breakdown value,and also led to an increase the proportion of weakly bound water and free water in the dough sheets,as well as a decrease in the content of wheat gluten protein polymers.With regard to dried noodles’ quality,adding YE led to a darker color of cooked noodles,with a slight decrease in hardness and elasticity.The sensory evaluation found that,except for YE1,the addition of other types of YE did not significantly differ from the taste of reduced-salt dried noodles alone.In terms of instant noodles quality,YE1 could not be used to make instant noodles,while adding the other types of YE resulted in a slight decrease in the hardness and elasticity of rehydrated instant noodles.But there was no unacceptable phenomenon in sensory evaluation.(3)The salt taste components in YE4 were separated and purified using ultrafiltration,gel filtration chromatography,and preparative liquid chromatography,using salt intensity as the criterion.UPLC-Q/TOF MS/MS identified the component with the highest salt intensity to have seven possible salty peptides,namely DIPVPKPK(DI8),KFGSSDK(KF7),KGNATGA(KG7),PGNPILK(PG7),ILISKKI(IL7),SGGGGGGAPS(SG10),and LYDNTNHIEEEV(LY12).Molecular docking results showed hydrogen bonds and salt bridges were the main binding forces between salty peptides and receptors.The binding energies of the docked complexes followed the order of KF7 < DI8 < LY12 < SG10 < PG7 <KG7 = IL7.Sensory evaluation of the chemically synthesized peptides showed that DI8,KF7,KG7,and LY12 had a salt taste,with respective salt threshold values of 0.16,0.20,0.32,and0.71 mg/m L,respectively,while PG7,IL7,and SG10 had no apparent salt taste.