Enhancement of ß-galactosidase catalytic activity and stability through covalent immobilization onto alginate/tea waste beads and evaluating its impact on the quality of some dairy products.

The current study aimed to evaluate the hydrolysis of whole fat milk (WFM) and sweet whey (SW) using ß-galactosidase (ß-gal) after covalent immobilization onto activated alginate/tea waste (Alg/TW) beads as a novel carrier. The optimum temperature for free and Alg/TW/ß-gal was 40 °C and the ideal pH was 7.0. However, Alg/TW/ß-gal displayed better stabilities at high temperatures and a wide pH range. Additionally, the value of Km and Vmax for Alg/TW/ß-gal was higher than the free enzyme. The Alg/TW/ß-gal showed better residual activity (78.6 %) after 90 storage days at 4 °C. The reusability of Alg/TW/ß-gal was very good as it conserved its full activity after 15 consecutive cycles and conserved 93 % of its initial activity after 10 cycles with ONPG (O-nitrophenyl-ß-D-galactopyranoside) and lactose as a substrate, respectively. The impact of Alg/TW/ß-gal on WFM and SW using HPLC analysis revealed a remarkable decrease in lactose concentration and increase of glucose and galactose concentrations. The SW exhibited higher degree of lactose hydrolysis (97.3 %) compared to WFM (62.4 %). Besides, SW had a prominent increase in total phenolic content (96.8 mg/L) compared to WFM (54.3 mg/L). The antioxidant activity had increased after enzyme treatment in both WFM and SW. The GC-MS analysis for volatile compounds identified twenty-five flavour constituents. Finally, Alg/TW/ß-gal has a potential application for obtaining healthy, acceptable, and commercial dairy products of low lactose.

Biochemical characterization and insights into the potency of the acidic Aspergillus niger NRC114 purified α-galactosidase in removing raffinose family oligosaccharides from soymilk yogurt.

BACKGROUND: Because humans lack α-galactosidase, foods containing certain oligosaccharides from the raffinose family, such as soybeans and other legumes, may disrupt digestion and cause flatulence. RESULTS: Aspergillus niger NRC114 α-galactosidase was purified using protein precipitation, gel filtration, and ion exchange chromatography steps, which resulted in a 123-fold purification. The purified enzyme was found to be 64 kDa using the SDS-PAGE approach. The optimum pH and temperature of the purified α-galactosidase were detected at pH 3.5 and 60 ºC, respectively. The pure enzyme exhibited potent acidic pH stability at pH 3.0 and pH 4.0 for 2 h, and it retained its full activity at 50 ºC and 60 ºC for 120 min and 90 min, respectively. The enzyme was activated using 2.5 mM of K+, Mg2+, Co2+, or Zn2+ by 14%, 23%, 28%, and 11%, respectively. The Km and Vmax values of the purified enzyme were calculated to be 0.401 µM and 14.65 µmol min-1, respectively. The soymilk yogurt showed an increase in its total phenolic content and total flavonoids after enzyme treatment, as well as several volatile compounds that were detected and identified using GC-MS analysis. HPLC analysis clarified the enzymatic action in the hydrolysis of raffinose family oligosaccharides. CONCLUSION: The findings of this study indicate the importance of A. niger NRC114 α-galactosidase enzyme for future studies, especially its applications in a variety of biological fields.

A statistical strategy for optimizing the production of α-galactosidase by a newly isolated Aspergillus niger NRC114 and assessing its efficacy in improving soymilk properties.

BACKGROUND: α-Galactosidase is widely distributed in plants, microorganisms, and animals, and it is produced by different fungal sources. Many studies have confirmed the valuable applications of α-galactosidase enzymes for various biotechnological purposes, like the processing of soymilk. RESULTS: Aspergillus niger NRC114 was exploited to produce the extracellular α-galactosidase. One factor per time (OFT) and central composite design (CCD) approaches were applied to determine the optimum parameters and enhance the enzyme production. The CCD model choices of pH 4.73, 1.25% mannose, 0.959% meat extract, and 6-day incubation period have succeeded in obtaining 25.22 U/mL of enzyme compared to the 6.4 U/mL produced using OFT studies. Treatment of soymilk by α-galactosidase caused an increase in total phenols and flavonoids by 27.3% and 19.9%, respectively. Antioxidant measurements revealed a significant increase in the enzyme-treated soymilk. Through HPLC analysis, the appearance of sucrose, fructose, and glucose in the enzyme-treated soymilk was detected due to the degradation of stachyose and raffinose. The main volatile compounds in raw soymilk were acids (45.04%) and aldehydes (34.25%), which showed a remarkable decrease of 7.82% and 20.03% after treatment by α-galactosidase. CONCLUSIONS: To increase α-galactosidase production, the OFT and CCD approaches were used, and CCD was found to be four times more effective than OFT. The produced enzyme proved potent enough to improve the properties of soymilk, avoiding flatulence and undesirable tastes and odors.

Physicochemical properties of and volatile compounds in riboflavin fortified cloudy apple juice; study of its effect on job fatigue among Egyptian construction workers.

Fatigue and rapid exhaustion are common complaints among construction workers, as a result of high-effort levels, physical overexertion, weather and long physically demanding work hours. This study aimed to fortify cloudy apple juice with riboflavin (vitamin B2) to evaluate changes in chemical composition, antioxidant activity and volatile compounds in the fortified juice and to study its effect on the volunteer construction workers complaining of fatigue resulting from demanding physical duties. Analysis of volatile compounds in the fortified cloudy apple juice using Gas Chromatography and Gas Chromatography-Mass Spectrometry identified thirty-four volatile compounds including esters, alcohols, aldehydes and acids. The most predominant volatile compounds were alcohols followed by esters in both the control and fortified samples. We studied the effect of the supplementation of riboflavin-fortified cloudy apple juice versus conventional cloudy apple juice on the anthropometric parameters, the scores of two fatigue questionnaires (Checklist Individual Strength and Fatigue Severity Scale) and antioxidants biomarkers among young Egyptian male construction workers. This study revealed that consumption of 1.3 mg of riboflavin-fortified cloudy apple juice per day for twenty-eight days significantly improved their metabolism, with a decrease in mean body fat percentage and an increase in body muscle mass without statistically significant differences, the fortified juice significantly improved the fatigue questionnaires' scores. Moreover, the fortified supplement had a substantial change in antioxidant activity; there was significant increase in the plasma total antioxidant capacity (+74.19 %change) and catalase enzyme (+54.65 %change) with a significant decrease in the serum malondialdehyde level (-53.78 %change). When compared to the administration of conventional cloudy apple juice, although there was a significant decrease in serum malondialdehyde level (-4.63 %change) at the end of the study, only the subjective fatigue subscale of the CIS fatigue score significantly decreased among the construction workers (-24.61 %change). It could be concluded that vitamin B2 fortified-cloudy apple juice was effective in the reduction of fatigue and exhaustion in the study's subjects.