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ABSTRACT The optimum reaction conditions (temperature 95°C, pH 6.5, time 70 min and cysteine 0.2 g) and significant influence factors were found by response surface model (RSM) experimentation to reduce bitterness and increase overall acceptability of soybean protein hydrolysate (SPH) using the Maillard reaction of arabinose. Three reaction products of different response values and sensory profiles were selected to be investigated further. Fourier transform infrared (FTIR) spectra and UV 294 and 420 nm analyses revealed their different extents of the Maillard reaction. Partial least squares regression analysis (PLSR) for free amino acids and molecular weight distribution and aroma compounds versus the used reaction conditions of the three samples suggested that reaction conditions of higher pH plus less Cys could cause more bitter amino acids (Leu, Val) and 500–1000 Da peptides, while those of more cysteine plus longer times under low temperatures benefitted formation of the umami amino acid of glutamic acid and > 1000 Da peptides. In particular, the reaction conditions of higher temperatures and more cysteine would generate more volatile compounds with roasted and meaty aromas unfavourable for overall acceptability. Furthermore, Pearson coefficient analysis revealed the key taste and aroma components and exposed that the fatty and caramel aromas contributed positively to overall acceptability. This study can provide references for debittering and improving the flavour of SPH. [ABSTRACT FROM AUTHOR]

The goal of this research is debittering of orange juices with enzimatic process. Naringinase enzim is produced with Penicillium decumbens. The research metode is complete random design with two variabel. The first variabel is concentration of enzim : 0,0; 200; 400 ppm and the second variabel is time of incubation : 1, 2 and 3 hours. The product of this research is tested ascorbic acid, Total Plate Count and organoleptic test. The result showed concentration of naringinase enzim 400 ppm and incubation 3 hours can eliminated the after taste of orangge juice without reduce the ascorbic acid and colour of orange juice.

Whey protein isolate (WPI) was hydrolysed to whey protein hydrolysates (WPH) of degree of hydrolysis equal to 15% using Protease N ‘Amano’ G (IUB 3.4.24.28) in a batch reactor at 55 °C and pH 7.0 according to the pH-stat procedure. Ash was removed by adsorbing WPH onto macroporous adsorption resins (MAR). Following rinsing with deionised water, desorption was achieved by washing with 20%, 40% and 75% alcohol (v v−1) to obtain the three fractions HS20, HS40 and HS75. Ash reduced from 15.71% (WPH) to 4.38% (HS20), 2.02% (HS40) and 2.38% (HS75). Similarly, the protein content was enriched from a low of 64.89% (WPH) to 94.74% (HS20), 95.32% (HS40) and 92.00% (HS75). The fractions were analysed for surface hydrophobicity (SHo), angiotensin-I converting enzyme (ACE) inhibition, emulsifying activity index, total amino acids composition and molecular weight distribution. Fraction HS75 was objectionably bitter, showed superior ACE inhibition (lowest IC50), had the highest content of hydrophobic and essential amino acids and contained about 71% of <600 Da with no fractions exceeding 4142 Da. Desorption with alcohol weakened the hydrophobic interaction forces between the peptides and resins and hence eluted the peptides, with the bitter HS75 being extracted. [ABSTRACT FROM AUTHOR]

Clarified, debittered grapefruit juice concentrate (64.2 °Bx) was produced by membrane filtration, debittering, and an evaporation process. Debittering by an XAD-16 adsorption column removed more than 78% of bitterness in grapefruit juice, based on naringin content. Also, some of the non-bitter flavonoids, such as narirutin and hesperidin, were nearly completely removed. Other values, such as vitamin C, and total phenolics, based on absorbance at 325 nm, were also reduced (P<0.05) after debittering. The vitamin C loss can probably be attributed to juice handling during processing. Absorption spectra in the 200–450 nm region showed characteristic absorption maxima around 280 and 322 nm in the control but no spectral fine structure in debittered concentrate. Besides differences in flavonoid profile, there was a slight difference in colour. Debittered concentrate had less chroma (CIE C*) and more lightness (CIE L*) than the control. Thus, the colour of debittered concentrate could be described as slightly paler than that of the control. [Copyright &y& Elsevier]

Leucine aminopeptidase (LAP), an exopeptidase that releases amino acid residues, especially leucine, from the N-terminus of polypeptides, is often applied to debitter protein hydrolysate in the food industry. However, there are no thermostable and high activity enzymes that can be used in the food industry. In this stud y , we obtained the highly active and thermostable leucine aminopeptidases screened from the thermophilic fungi Thermomyces lanuginosus , Talaromyces thermophilus , and Malbranchea cinnamomea. The activity of the recombinant leucine aminopeptidase Thelap was significantly increased to 2771.5 U/mL, as mediated by the CRISPR/Cas9 tool. The recombinant Thelap was easily purified from fermentation broth by Ni-affinity chromatography, and the specific activity of the purified Thelap was increased to 7449.6 U/mg. The recombinant Thelap showed optimal activity at pH 8.5 and 75 °C and remained above 70% of the maximum activity over a wide temperature range (30–80 °C). With regard to temperature stability, Thelap retained more than 90% activity when it was incubated at 65–75 °C for 2 h. K+ and Co2+ increased the enzyme activity of the recombinant Thelap, while Ba2+, Mn2+, Ni2+, Ca2+, Mg2+ and SDS inhibited its enzyme activity, and the inhibition capacity of Mg2+ was the weakest. Upon application in soy protein hydrolysis, Thelap could significantly increase the degree of hydrolysis and remove more hydrophobic amino acids from the N-terminal region of the polypeptide to decrease the bitterness. • The thermostable leucine aminopeptidase from Thermomyces lanuginosus was expressed at a high level in A. niger strain HL-1. • The recombinant Thelap activity of the shake fermentation supernatant achieved 2771.5 U/mL, mediated by the CRISPR/Cas9 tool. • Characterization of the purified enzyme was performed by measuring the optimal temperature, pH and the effects of metal ions. • Thelap could further improve the degree of hydrolysis and decrease bitterness during application in soy protein. [ABSTRACT FROM AUTHOR]