Effect of rice bran protein concentrate as wall material adjunct on selected physicochemical and release properties of microencapsulated ß-carotene.

Rice bran protein is an emerging protein source from rice milling that possesses health benefits and emulsifying capacity suitable for hypoallergenic encapsulation applications, especially for lipophilic compounds such as ß-carotene. The purpose of this study is to develop and characterize ß-carotene encapsulates with maltodextrin and rice bran protein. Rice bran protein was prepared using conventional alkali extraction. ß-carotene was added to the composite wall materials (50:50 of 4%, 8%, 12%, and 16% solids content) and spray-dried. Encapsulation efficiency (85-98%) and radical scavenging activity (11-43%) varied proportionally with rice bran protein. Across increasing maltodextrin and rice bran protein content of the feed, carbohydrate content of the microcapsules varied proportionally (50-66%) but protein content was uniform (10-13%). Scanning electron microscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy data suggested successful encapsulation. Release profiles showed decreasing trend with increasing rice bran protein content; co-digestion with rice mitigated negative impacts of rice bran protein. Microcapsules with nutritive potential and health-promoting properties were developed as potential carotenoid delivery systems.

In Vitro Release Kinetics of Microencapsulated Materials and the Effect of the Food Matrix.

Many biomaterials are encapsulated to preserve their health-promoting properties and promote targeted delivery. Numerous papers have been published about extraction and purification methods, encapsulation techniques, and release properties of encapsulated biomaterials. Despite the abundant information, the food applications of encapsulated materials are currently limited. One approach to increase the food applications is to investigate the mathematical aspects of release behavior and the effect of the food matrix. Such information is useful in evaluating suitable food matrices and predicting the extent of bioavailability of the biomaterial. This review aims to discuss the kinetic models of release, current efforts to promote sustained release, and food matrices currently used in in vitro investigations. Information from pharmaceutical studies is integrated and reviewed to determine possible food applications. Future research on microencapsulated biomaterials conducted along these aspects may hopefully hasten nutraceutical applications.

LnqR, a TetR-family transcriptional regulator, positively regulates lacticin Q production in Lactococcus lactis QU 5.

Lacticin Q is an unmodified leaderless bacteriocin produced by Lactococcus lactis QU 5. It has been revealed that the production and self-immunity of lacticin Q are facilitated by a gene cluster lnqQBCDEF The gene for a putative TetR-family transcriptional regulator, termed lnqR, was found nearby the lnqQBCDEF cluster, but its involvement in lacticin Q biosynthesis remained unknown. In this study, we created an LnqR-overexpressing QU 5 recombinant by using lactococcal constitutive promoter P32 The recombinant QU 5 showed enhanced production of and self-immunity to lacticin Q. RT-PCR analysis has revealed that an overexpression of LnqR increases the amounts of lnqQBCDEF transcripts, and these six genes are transcribed as an operon in a single transcriptional unit. Interestingly, LnqR expression and thus lacticin Q production by L. lactis QU 5 was found temperature dependent, while LnzR, an LnqR-homologue, in L. lactis QU 14 was expressed in a similar but not identical manner to LnqR, resulting in dissimilar bacteriocin productivities by these strains. This report demonstrates LnqR as the first TetR-family transcriptional regulator involved in LAB bacteriocin biosynthesis and that, as an exceptional case of TetR-family regulators, LnqR positively regulates the transcription of these biosynthetic genes.

In vitro release properties of encapsulated blueberry (Vaccinium ashei) extracts.

We aimed to determine the effect of encapsulation on the release properties of blueberry extracts during simulated gastrointestinal digestion. An ethanolic pomace extract was microencapsulated with whey protein isolate via spray drying. The in vitro release of monomeric anthocyanins, phenolics and ferric reducing antioxidant activity of the microcapsules (W) were evaluated for the microcapsules and two non-encapsulated systems: ethanolic pomace extract (P) and freeze-dried juice (F). Concentrations of anthocyanin and phenolics were normalised prior to digestion. Results showed that antioxidant activity was in the order of: F>W>P. Regardless of encapsulation, more phenolics were released from W and P than F. Anthocyanin concentration decreased after intestinal digestion for W, but remained constant for P and F. MALDI-MS showed similar spectra for P and F but not for W. The spray-dried product has comparable release characteristics to freeze-dried juice, and may be investigated for food applications.

Total phenolics content and antioxidant capacities of microencapsulated blueberry anthocyanins during in vitro digestion.

The goal of this research was to investigate the change in phenolics content and antioxidant capacity of microencapsulated anthocyanins (ACNs) digested in vitro. Blueberry ACN microcapsules were prepared from two wall materials (whey protein isolate and gum arabic) and ACN powder, previously extracted with three solvent systems (acetonic, ethanolic, methanolic); this was then spray-dried. The physicochemical properties and release characteristics of the microcapsules were evaluated. Rehydrated gum arabic microcapsules retained more total ACNs but less ferric reducing power than did whey protein microcapsules. Ethanolic extracts retained most of the total ACNs while methanolic extracts possessed the highest antioxidant capacity. During in vitro digestion, gum arabic microcapsules had high release rates of phenolics with high antioxidant activity during the gastric phase. Whey protein microcapsules had comparably lower release rates but high antioxidant activity throughout digestion.

Microencapsulation of tannic acid for oral administration to inhibit carbohydrate digestion in the gastrointestinal tract.

The prevalence of diabetes mellitus and obesity is rapidly rising worldwide. Recently, there is increasing evidence that phytochemicals such as polyphenols in our diet could directly inhibit the activities of key digestive enzymes, representing a novel method of controlling and preventing diabetes mellitus and obesity. More research is required to determine how to effectively utilize phytochemicals within the gastrointestinal (GI) tract to obtain maximum inhibition of digestive enzymes. This study investigated the inhibition efficiency of tannic acid (TA) on α-amylase as compared with other potential inhibitors using an in vitro method. The inhibition mode and kinetics were studied. The results showed that tannic acid (TA) is more effective in inhibiting α-amylase than a commercial starch blocker (Phase 2 Starch Blocker), and some selected flavonoids and polyphenols including quercetin, rutin, and polyphenon from green tea. It is also found that inhibition of α-amylase by TA in the GI tract is difficult if administered orally due to the non-specific and reversible noncompetitive interaction between tannic acid and α-amylase or other proteins. Accordingly, a pH-sensitive delivery system using calcium-alginate microspheres encapsulating tannic acid was successfully developed for oral administration to inhibit carbohydrate digestion in the GI tract. The encapsulated TA in calcium-alginate microspheres could be protected from the proteins in the stomach, and sustain release and inhibit α-amylase activity in the small intestine.

Antioxidant and enzyme inhibitory activities of blueberry anthocyanins prepared using different solvents.

We compared the biological activities of anthocyanins prepared from whole blueberries or pomace and extracted with acetone, ethanol, and methanol. Crude Amberlite extracts (CAE) and rehydrated powders of freeze-dried anthocyanins were used. Ethanolic CAE yielded the highest total monomeric anthocyanin content [TMAC] (160 ppm), ferric reducing antioxidant power [FRAP] (3.4 mM Fe(2+)), total phenolics content [TPC] (382 ppm gallic acid equivalents [GAE]), and α-amylase inhibitory activity (36.8%). The rehydrated powder from acetonic extract gave the greatest FRAP (5.19) and TPC (422.7). α-Amylase (26.1%) and α-glucosidase (91.5%) inhibitory activities were also sustained. Methanolic CAE yielded values intermediate between ethanolic and acetonic extracts. Comparison of mass spectra between Amberlite extracts and rehydrated preparations revealed putative degradation and dimerization products in the rehydrated powders, which could account for loss in biological activities for rehydrated methanolic and ethanolic powders. Results of this study provide useful information in optimizing anthocyanin preparation methods for improved biological activity.