Anthocyanin‐fortified konjac glucomannan/sodium alginate composite edible boba: characteristics of texture, microstructure, in vitro release behaviour and antioxidant capacity

Abstract

Konjac glucomannan/sodium alginate composite edible boba (KGM/SA-boba) with good taste is very popular in China, and it is an outstanding carrier for health potential ingredients. In this work, KGM/ SA-boba were fortified with 0.25, 0.50, 0.75 and 1.00% purple sweet potato anthocyanin (PSPA), then characterised by the water distribution, texture, microstructure, in vitro release property of PSPA and antioxidant capacity. LF-NMR analysis demonstrated that the free water of KGM/SA-boba could transfer to tightly bound water with the addition of PSPA that made it with better water-binding ability, higher springiness and lower hardness. And the results of SEM and rheology showed that PSPA could stabilise the microstructure of KGM/SA-boba by forming more amorphous regions and hydrogen bonds proved by the results of DSC and FT-IR. Furthermore, 50% of PSPA in PSPA-fortified KGM/SA-boba can be released at the first hour in a simulated gastrointestinal environment. And the scavenging capacity of DPPH and ABTS of the PSPA-fortified KGM/SA-boba after digestion was higher than that of PSPA alone. Generally, PSPA could improve the texture while KGM/SA-boba in turn would make PSPA more stable in the gastrointestinal digestive system.

Enhanced Functionality and Bio-Accessibility of Composite Pomegranate Peel Extract-Enriched “Boba Balls”

“…The “Boba balls” production was performed by the methodology of Liu, Xiao, Feng, Zhang, Li, Tu and Niu [ 2 ], with the formulation and “Boba ball” production modifications illustrated in Figure 1 . Firstly, 10 g of gelatin and PPE at 0, 1, 2 and 3% ( w / v ) concentrations were dissolved in 70 mL of pomegranate juice (PJ) for 5 min at 40 °C on a magnetic stirrer, and separately, SA (1.5 g) was dissolved in distilled water (30 mL) for 5 min at 70 °C on a magnetic stirrer.…”

“…“Boba balls” containing PPE extract were directly placed on the center of heavy-duty platform, and the probe was compressed to 50% of samples at a 5 mm/s test speed. The waiting time between the two cycles of the compression was 5 s, and 10 different “Boba balls” were subjected to testing at room temperature [ 2 ].…”

“…Customarily, they acquire their color and flavor from brown sugar, but may incorporate other colors or flavors [ 1 ]. “Boba balls” can also be produced with various carbohydrate and/or protein-based gel-forming polymers that can complex with sodium alginate and are generally known for high elasticity, resilient mouthfeel, edible convenience, and low calorie content [ 2 ]. “Boba balls” began to become widespread in Taiwan in the early 1980s and are usually consumed with milk tea.…”

“…Considering the consumption and market value of “Boba balls”, it is obvious that enriching these products with plant extracts rich in functional properties will significantly contribute to human health. In a study, Liu, Xiao, Feng, Zhang, Li, Tu and Niu [ 2 ] produced “Boba balls” with konjac glucomannan/sodium alginate composite gels and enriched “Boba balls” with purple-potato-anthocyanin extracts to increase gastrointestinal digestion stability. The enrichment of “Boba balls” with herbal extracts obtained from food processing by-products will improve the nutritional properties of “Boba balls” as well as improve the bio-availability of herbal extracts.…”

“…The reaction occurring between the sodium alginate and the CaCl 2 is called ionic gelation. Thus, different core materials such as purple-sweet-potato anthocyanin [ 2 ] and orange flavor [ 6 ] have been encapsulated in the “Boba balls”. The encapsulation of active ingredients from food industry by-products in “Boba balls” will increase the utilization rate of active ingredients during the consumption of these products, thus enabling the consumption of healthier and bio-available products.…”