Microbial L-asparaginase for Application in Acrylamide Mitigation from Food: Current Research Status and Future Perspectives

Abstract

L-asparaginase (E.C.3.5.1.1) hydrolyzes L-asparagine to L-aspartic acid and ammonia, which has been widely applied in the pharmaceutical and food industries. Microbes have advantages for L-asparaginase production, and there are several commercially available forms of L-asparaginase, all of which are derived from microbes. Generally, L-asparaginase has an optimum pH range of 5.0–9.0 and an optimum temperature of between 30 and 60 °C. However, the optimum temperature of L-asparaginase from hyperthermophilic archaea is considerable higher (between 85 and 100 °C). The native properties of the enzymes can be enhanced by using immobilization techniques. The stability and recyclability of immobilized enzymes makes them more suitable for food applications. This current work describes the classification, catalytic mechanism, production, purification, and immobilization of microbial L-asparaginase, focusing on its application as an effective reducer of acrylamide in fried potato products, bakery products, and coffee. This highlights the prospects of cost-effective L-asparaginase, thermostable L-asparaginase, and immobilized L-asparaginase as good candidates for food application in the future.

Low Acrylamide Flatbreads from Colored Corn and Other Flours

“…Žilić et al [21] also found that the asparagine content of flours, including blue corn, affected the acrylamide content of biscuits. A related study [31] found that different commercial brands of corn products had wide-ranging amounts of acrylamide (<30-410 µg/kg), suggesting that consumers have a choice of selecting commercial corn-based and other foods with low acrylamide content. These include flatbreads prepared from corn flour as well as almond flour, peanut meal, wheat flour, quinoa flour-peanut meal, wheat flour-spinach, wheat flour-peanut meal-beets, wheat flour-peanut meal-broccoli, yellow corn-wheat tortillas, and wraps ((26.5-56.5 µg/kg, Figure 2) and (3.83-49.1 µg/kg, Figure 3)).…”

“…Since the levels of asparagine as a proportion of the total free amino acid pool seem to be a key component in acrylamide formation, Muttucumaru et al [32] suggest that plant genetic studies might reduce the asparagine content of plant foods by blocking enzymes involved in its biosynthesis. A complementary approach involves postharvest treatment of plant foods before thermal processing with the enzyme asparaginase, which catalyzes the hydrolysis of asparagine to aspartic acid and ammonia [31]. These promising enzymatic methods merit study with corn and other cereal seeds.…”

Highly Active Thermophilic L-Asparaginase from Melioribacter roseus Represents a Novel Large Group of Type II Bacterial L-Asparaginases from Chlorobi-Ignavibacteriae-Bacteroidetes Clade

“…Type-II enzymes are located in the periplasmic space. They exhibit high specific activity against L-Asn with K M values in two orders of magnitude lower (micromolar K M ) compared to bacterial type I L-ASNases [13].…”

“…Continuous research efforts to discover new promising L-ASNases for different fields of biotechnology have turned this group of enzymes into a growing family with amazing diversity. L-ASNases have been isolated from many archaea, bacteria, fungi, and yeast [3,13], and L-ASNases of plant and mammalian origin are now also known [14][15][16].…”

“…According to the classification historically applied, L-ASNases are divided into three major groups: bacterial-type L-asparaginases, plant-type L-asparaginases, and Rhizobialtype L-asparaginases [13].…”