Journal of Food Technology Research

Physicochemical and functional characteristics of protein co-precipitates from tempeh and egg white flours

Ervika Rahayu Novita Herawati — 2026-02-18

Recent developments in Indonesia have seen a growing interest in tempeh, with new activities emerging that combine animal and plant proteins through innovative processing technologies. This study examined the blending of egg white and tempeh flour (TF) using a co-precipitation method. The process involved solubilizing the proteins at pH 12, followed by precipitation at the isoelectric point around pH 4.4. Four types of precipitates were produced based on the protein source: co-precipitate of mixed tempeh flour (FMP), egg white protein co-precipitate (EMP), tempeh flour precipitate (TFP), and egg white precipitate (EFP). Among these, FMP demonstrated superior qualities, containing 79.68% protein and achieving 89.80% in vitro digestibility. Notably, the protein was enriched with essential amino acids such as lysine, leucine, and methionine compared to single-source proteins. Functionally, FMP exhibited excellent water and oil holding capacities, measuring 512.82% and 233.82%, respectively. Supporting analyses confirmed these findings: FTIR indicated minor shifts in amide bands, primarily secondary structures; SEM revealed porous, water-stable structures capable of absorption; SDS-PAGE showed minimal fragmentation, with protein bands characteristic of soybean and egg white proteins (15-75 kDa). The bioactive profile of FMP included antioxidant activity (9.45% RSA via DPPH), moderate antioxidant capacity, phenolic content of 4.44 mg gallic acid equivalents per gram, and detectable isoflavones such as daidzein (17.77 mg/100 g) and genistein (3.16 mg/100 g). These results support the potential of locally co-precipitated proteins to contribute to functional food innovation and development.

Alginate–gum Arabic beads for encapsulation of longan extract: Improving efficiency, stability, and safety

Varunya Fuangchoom — 2026-02-19

Phenolic compounds from longan (Dimocarpus longan Lour.) extract possess strong antioxidant properties but are highly unstable during processing and storage, limiting their application in functional foods. This study aimed to develop an alginate–gum Arabic encapsulation system to enhance the efficiency, stability, and microbial safety of longan phenolic compounds. Beads were produced using an extrusion technique with 1.5% (w/v) sodium alginate and 4% (w/v) calcium chloride as the optimal gelling condition, and gum Arabic was incorporated as a co-polymer to improve bead performance. The formulation containing gum Arabic exhibited the highest encapsulation efficiency (74.9%), and stability evaluations revealed superior retention of phenolic compounds under acidic conditions (pH 2), with a more controlled release profile compared to neutral and alkaline environments. To address microbial safety, gamma irradiation at 5 and 7.5 kGy was applied; a dose of 5 kGy increased bead firmness, whereas 7.5 kGy achieved complete sterilization without compromising structural integrity or functional properties. These findings indicate that the integration of alginate with gum Arabic significantly enhances both encapsulation performance and bioactive stability, while gamma irradiation serves as an effective non-thermal sterilization method. The developed system demonstrates strong potential for application as a delivery platform in functional food and nutraceutical formulations requiring stability and safety assurance.

Effect of a mixture of nut residue powder, potato starch and instant dry yeast on the quality of sandwich bread

Tran Huu Duy — 2026-02-19

This study employed a combination of nut residue powders (soy, peanut, and cashew) to partially replace wheat flour in a sandwich bread formulation. In the initial trial, the nut residue mixture (NRM) powders, substituting wheat flour at levels ranging from 10% to 17.5%, were coded as G1 through G4, with a control sample G0 containing 100% wheat flour. Subsequently, potato starch (PS) (6% to 10%) was incorporated as a substitute for wheat flour, and instant dry yeast (0.5% to 0.7%) was added to enhance the physical qualities of the final product. Among the four recipes designed for partial wheat flour replacement, the results indicated that bread from Recipe G2, which contained NRM powder and wheat flour in a ratio of 12.5:87.5%, exhibited high specific volume and volume expansion, along with moderate hardness (727.37 and 277.90 grams-force, respectively) and an appealing color. However, the specific volume and volume expansion of G2 bread remained lower than those of the control G0. The subsequent partial replacement of wheat flour with potato starch and the use of quick-dry yeast compensated for this shortcoming. The formulation, referred to as PI, with a ratio of PS:NRM: wheat flour of 7.79:12.5:79.71% and yeast at 0.56%, produced a product with superior structure and higher contents of protein, fat, fiber, ash, and total polyphenols compared to G0. Notably, the fiber content in the PI sample was approximately 3.3 times higher. Additionally, the estimated glycemic index (eGI) of the PI bread was lower at 51.16 compared to 67.6 for G0, indicating a medium-low glycemic response. This research demonstrates the effective utilization of by-products in food processing and suggests potential for further application in the bakery industry or other food sectors where demand exists for healthier and functional products.