Precision cellular agriculture: The future role of recombinantly expressed protein as food.

Cellular agriculture is a rapidly emerging field, within which cultured meat has attracted the majority of media attention in recent years. An equally promising area of cellular agriculture, and one that has produced far more actual food ingredients that have been incorporated into commercially available products, is the use of cellular hosts to produce soluble proteins, herein referred to as precision cellular agriculture (PCAg). In PCAg, specific animal- or plant-sourced proteins are expressed recombinantly in unicellular hosts-the majority of which are yeast-and harvested for food use. The numerous advantages of PCAg over traditional agriculture, including a smaller carbon footprint and more consistent products, have led to extensive research on its utility. This review is the first to survey proteins currently being expressed using PCAg for food purposes. A growing number of viable expression hosts and recent advances for increased protein yields and process optimization have led to its application for producing milk, egg, and muscle proteins; plant hemoglobin; sweet-tasting plant proteins; and ice-binding proteins. Current knowledge gaps present research opportunities for optimizing expression hosts, tailoring posttranslational modifications, and expanding the scope of proteins produced. Considerations for the expansion of PCAg and its implications on food regulation, society, ethics, and the environment are also discussed. Considering the current trajectory of PCAg, food proteins from any biological source can likely be expressed recombinantly and used as purified food ingredients to create novel and tailored food products.

Roles of Plant-Specific Inserts in Plant Defense.

Ubiquitously expressed in plants, the plant-specific insert (PSI) of typical plant aspartic proteases (tpAPs) has been associated with plant development, stress response, and defense processes against invading pathogens. Despite sharing high sequence identity, structural studies revealed possible different mechanisms of action among species. The PSI induces signaling pathways of defense hormones in vivo and demonstrates broad-spectrum activity against phytopathogens in vitro. Recent characterization of the PSI-tpAP relationship uncovered novel, nonconventional intracellular protein transport pathways and improved tpAP production yields for industrial applications. In spite of research to date, relatively little is known about the structure-function relationships of PSIs. A comprehensive understanding of their biological roles may benefit plant protection strategies against virulent phytopathogens.

A heating method for producing frozen pizza ingredients with increased total polyphenol content and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity.

Despite growing demand for more healthful frozen pizza, current technologies for increasing potential healthfulness such as reformulation or enrichment of raw ingredients may lead to undesirable changes in the final product. This study evaluated alternative heat treatments of selected frozen pizza ingredients as methods for increasing the healthfulness of frozen pizza. Four common vegetable toppings (i.e., onion, corn, Japanese green pepper, and red pepper) were heated on a 250°C hot plate, and commercially available par-baked pizza base was reheated at 500°C for 50 s to induce browning. These alternatively heat-treated (AHT) ingredients were compared to their conventional counterparts (e.g., steam-blanched vegetable toppings and commercially available par-baked pizza base, respectively) in terms of total polyphenol content (TPC) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH RSA). TPC increased and was correlated with internal temperature for onion and peppers during alternative heat treatment, while increases in DPPH RSA of AHT onion and pizza base may be due to the formation of Maillard reaction products. Replacing conventional samples with AHT counterparts increased TPC and DPPH RSA by 1.2-fold to 1.6-fold and 1.3-fold to 2.1-fold, respectively, for vegetable toppings after reheating at 230°C for 12 min. Significant differences in acceptability of sensory attributes (i.e., appearance, taste, aroma, texture, and overall preference) were not observed between AHT and conventional vegetable topping when incorporated into pizza. These results suggest that alternative heat treatment of raw ingredients, particularly vegetable toppings, for the purpose of increasing TPC and DPPH RSA may be a viable method for increasing the potential healthfulness of frozen pizza.

Mechanisms of Docosahexaenoic and Eicosapentaenoic Acid Loss from Pacific Saury and Comparison of Their Retention Rates after Various Cooking Methods.

The docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) contents of Pacific saury (Cololabis saira), a fatty fish and staple of the Japanese diet, have been reported to decrease after cooking. This study compared the DHA and EPA contents remaining in saury after grilling, pan-frying or deep-frying to center temperatures of 75, 85, or 95 °C, and examined physical loss, lipid oxidation, and thermal degradation as mechanisms of DHA and EPA loss. Temperature changes inside the saury were monitored using thermocouples, while DHA and EPA contents, oxygen radical absorbance capacity, and measurements of lipid oxidation (that is, carbonyl value and thiobarbituric acid value) were determined chemically. Visualization of temperature distribution inside fish samples during cooking revealed large differences in heat transfer among cooking methods. True retention rates in grilled (DHA: 84 ± 15%; EPA: 87 ± 14%) and pan-fried samples (DHA: 85 ± 16%; EPA: 77 ± 17%) were significantly higher than deep-fried samples (DHA: 58 ± 17%; EPA: 51 ± 18%), but were not affected by final center temperatures despite differences in cooking times. Physical loss via cooking losses (grilling and pan-frying) or migration into frying oil (deep-frying) accounted for large quantities of DHA and EPA loss, while lipid oxidation and thermal degradation did not appear to be major mechanisms of loss. The antioxidant capacity of saury was not significantly affected by cooking treatments. The results of this study suggest that minimization of physical losses during cooking may increase DHA and EPA contents retained in cooked Pacific saury.

Effects of production factors and egg-bearing period on the antioxidant activity of enzymatic hydrolysates from shrimp (Pandalopsis dispar) processing byproducts.

The effects of production factors (protease used, percent enzyme, hydrolysis time, and water-to-substrate ratio) on the antioxidant activity of hydrolysates produced from shrimp processing byproducts (SPB) were assessed using Taguchi's L16 (4(5)) fractional factorial design. SPB hydrolysates showed excellent ABTS radical scavenging activity, metal ion chelating capacity, and inhibition of lipid peroxidation, but weak DPPH radical scavenging activity and ferric ion reducing antioxidant power. The protease used significantly influenced antioxidant activities while hydrolysis time and percent enzyme affected radical scavenging activities and inhibition of lipid peroxidation, respectively. Differences in the lipid and amino acid contents observed between SPB collected early and late in the egg-bearing period may have contributed to the slight variance in antioxidant activities displayed by their hydrolysates. Nevertheless, SPB hydrolysates produced using Alcalase or Protamex had high antioxidant activity regardless of production factors and egg-bearing period.

The role of molecular size in antioxidant activity of peptide fractions from Pacific hake (Merluccius productus) hydrolysates.

The antioxidative properties of Pacific hake hydrolysates and their peptidic fractions varying in molecular size were assessed. Hydrolysates produced by different proteases (Alcalase, bromelain, Flavourzyme, Protamex, Protease A"Amano"2, Protease N"Amano"K, Protin SD NY10, Umamizyme-K, Validase BNP-L, Validase FPexo) generally possessed good metal ion chelating (33-73% at 3mg/ml), DPPH radical scavenging (18-30% at 1mg/ml), ferric ion reducing power (abs700nm 0.36-0.86 at 3 mg/ml) and ABTS radical scavenging (47-85% at 0.067 mg/ml) activity, as well as a good capability to suppress lipid peroxidation in a linoleic acid model system. Peptide size (<1.4 kDa) was important for ABTS radical scavenging activity, whereas specific peptide composition (which depended on the particular protease used) was the governing factor for effective lipid peroxidation. Validase BNP-L was the most promising enzyme for producing Pacific hake hydrolysates with good antioxidative activity in various assays and similar effectiveness as the synthetic antioxidant BHT to inhibit lipid peroxidation.