Tuning the Functional Properties of Polysaccharide–Protein Bio‐Based Edible Films by Chemical,Enzymatic, and Physical Cross‐Linking

Among natural biopolymers, polysaccharides and proteins are very promising for biodegradable and edible wraps with different characteristics, so that their formulations can be tailor‐made to suit the needs of a specific commodity. Films prepared from polysaccharides have good gas barrier properties but exhibit lower resistance to moisture compared to protein films (edible) or polylactide films (biodegradable). Protein‐based films show better mechanical and oxygen barrier properties compared to polysaccharide films. For that reason, film performances may be enhanced by producing blend systems, where hydrocolloids (mixtures of proteins and/or polysaccharides) form a continuous and more cohesive network. However, the lower water barrier properties of hydrocolloid films and their lower mechanical strength in comparison with synthetic polymers limit their applications in food packaging. Therefore, the enhancement of biopolymer film properties has been studied to attain appropriate applications. This review provides an extensive synthesis of the improvement of the properties of edible polysaccharide–protein films by way of various chemical, enzymatic, and physical methods. These methods primarily aim at improving the mechanical resistance. They also permit to ameliorate the water and gas barrier properties and related functional properties.     

Sensory and Physicochemical Studies of Thermally Micronized Chickpea (Cicer arietinum) and Green Lentil (Lens culinaris) Flours as Binders in Low‐Fat Beef Burgers

Pulses are known to be nutritious foods but are susceptible to oxidation due to the reaction of lipoxygenase (LOX) with linolenic and linoleic acids which can lead to off flavors caused by the formation of volatile organic compounds (VOCs). Infrared micronization at 130 and 150 °C was investigated as a heat treatment to determine its effect on LOX activity and VOCs of chickpea and green lentil flour. The pulse flours were added to low‐fat beef burgers at 6% and measured for consumer acceptability and physicochemical properties. Micronization at 130 °C significantly decreased LOX activity for both flours. The lentil flour micronized at 150 °C showed a further significant decrease in LOX activity similar to that of the chickpea flour at 150 °C. The lowering of VOCs was accomplished more successfully with micronization at 130 °C for chickpea flour while micronization at 150 °C for the green lentil flour was more effective. Micronization minimally affected the characteristic fatty acid content in each flour but significantly increased omega‐3 and n‐6 fatty acids at 150 °C in burgers with lentil and chickpea flours, respectively. Burgers with green lentil flour micronized at 130 and 150 °C, and chickpea flour micronized at 150 °C were positively associated with acceptability. Micronization did not affect the shear force and cooking losses of the burgers made with both flours. Formulation of low‐fat beef burgers containing 6% micronized gluten‐free binder made from lentil and chickpea flour is possible based on favorable results for physicochemical properties and consumer acceptability.     

Potent Antidiabetic Activity and Metabolite Profiling of Melicope Lunu‐ankenda Leaves

Diabetes mellitus is normally characterized by chronic hyperglycemia associated with disturbances in the fat, carbohydrate, and protein metabolism. There is an increasing trend of using natural products instead of synthetic agents as alternative therapy for disorders due to their fewer side effects. In this study, antidiabetic and antioxidant activities of different Melicope lunu‐ankenda (ML) ethanolic extracts were evaluated using inhibition of α‐glucosidase and 2,2‐diphenyl‐l‐picrylhydrazyl (DPPH) radicals scavenging activity, respectively; whereas, proton nuclear magnetic resonance (¹H NMR) and ultra‐high performance liquid chromatography‐tandem mass spectrometric (UHPLC‐MS/MS) techniques were used for metabolite profiling of ML leaf extracts at different concentrations of ethanol and water. Sixty percent of ethanolic ML extract showed highest inhibitory effect against α‐glucosidase enzyme (IC₅₀ of 37 μg/mL) and DPPH scavenging activity (IC₅₀ of 48 μg/mL). Antidiabetic effect of ML extracts was also evaluated in vivo and it was found that the high doses (400 mg/Kg BW) of ML extract exhibited high suppression in fasting blood glucose level by 62.75%. The metabolites responsible for variation among ML samples with variable ethanolic levels have been evaluated successfully using ¹H‐NMR–based metabolomics. The principal component analysis (PCA) and partial least squares(PLS) analysis scores depicted clear and distinct separations into 4 clusters representing the 4 ethanolic concentrations by PC1 and PC2, with an eigenvalue of 69.9%. Various ¹H‐NMR chemical shifts related to the metabolites responsible for sample difference were also ascribed. The main bioactive compounds identified attributing toward the separation included: isorhamnetin, skimmianine, scopoletin, and melicarpinone. Hence, ML may be used as promising medicinal plant for the development of new functional foods, new generation antidiabetic drugs, as a single entity phytomedicine or in combinational therapy.     

Correlation of In Vivo and In Vitro Assay Results for Assessment of Free Radical Scavenging Activity of Green Tea Nutraceuticals

Green tea (GT)‐derived catechins; epigallocatechin gallate (EGCG) in particular are commonly used nutraceuticals for their free‐radical scavenging activity (FRSA). The influence of photodegradation on the protective power of GT nutracenticals against oxidative stress was thoroughly explored. Photodegradation of GT extracts was carried out and monitored using orthogonal stability‐indicating testing protocol; in vitro and in vivo assays. Total polyphenol content (TPC) and FRSA were determined spectrophotometrically while EGCG was selectively monitored using SPE‐HPLC. In vivo assessment of photodegraded samples was investigated via measuring a number of biomarkers for hepatic oxidative stress and apoptosis (caspase‐3, inducible nitric oxide synthase, nitric oxide, mitogen‐activated protein kinase, glutathione, thiobarbituric acid reactive substances, nuclear factor kappa beta, and nuclear factor erythroid 2‐related factor) as well as liver damage (alanine transaminase and aspartate transaminase) in serum of rats previously subjected to oxidative stress. Results showed complete degradation of EGCG in photodegraded green tea samples with no correlation with either TPC or FRSA. On the other hand, in vivo assay results revealed not only loss of activity but formation of harmful pro‐oxidants. Photostability was found crucial for the protective effect of GT extract against lead acetate insult. Results confirmed that careful design of quality control protocols requires correlation of chemical assays to bioassays to verify efficacy, stability, and most importantly safety of nutraceuticals.     

Esterification of Quercetin Increases Its Transport Across Human Caco‐2 Cells

Plant polyphenols showed useful biochemical characteristics in vitro; however, the assessments of their clinical applications in vivo are restricted by their limited bioavailability due to their strong resistance to 1st‐pass effects during absorption. In order to improve the bioavailability of quercetin (QU), the ester derivative of QU (3,3′,4′,5,7‐pentahydroxy flavones, TAQU) was synthesized, followed by examining the oil–water partition coefficient as well as the transport mechanisms of QU and its ester derivative (TAQU) using human Caco‐2 cells. The transport characteristics of QU and TAQU transport under different conditions (different concentrations, time, pH, temperature, tight junctions, and potential transporters) were systematically investigated. Results showed that QU had a lower permeability coefficient (2.82 × 10^?6 cm/s) for apical‐to‐basolateral (AP‐BL) transport over 5 to 50 μM, whereas the transport rate for AP to BL flux of TAQU (5.23 × 10^?6 cm/s) was significantly greater than that of QU. Paracellular pathways were not involved during the transport of both QU and TAQU. QU was poorly absorbed by active transport, whereas TAQU was mostly absorbed by passive diffusion. Efflux transporters, P‐glycoproteins, multidrug resistance proteins were proven to participate in the transport process of QU, but not in that of TAQU. These results suggested that improving the lipophicity of QU by esterification could increase the transport of QU across Caco‐2 cells.     

In vitro fermentation of cereal dietary fibre carbohydrates by probiotic and intestinal bacteria

A range of probiotic and other intestinal bacteria were examined for their ability to ferment the dietary fibre carbohydrates β‐glucan, xylan, xylo‐oligosaccharides (XOS) and arabinoxylan. β‐Glucan was fermented by Bacteroides spp and Clostridium beijerinckii but was not fermented by lactobacilli, bifidobacteria, enterococci or Escherichia coli. Unsubstituted xylan was not fermented by any of the probiotic bacteria examined. However, many Bifidobacterium species and Lactobacillus brevis were able to grow to high yields using XOS. XOS were also efficiently fermented by some Bacteroides isolates but not by E coli, enterococci, Clostridium difficile, Clostridium perfringens or by the majority of intestinal Lactobacillus species examined. Bifidobacterium longum strains were able to grow well using arabinoxylan as the sole carbon source. These organisms hydrolysed and fermented the arabinosyl residues from arabinoxylan but did not substantially utilise the xylan backbone of the polysaccharide. Arabinoxylan was not fermented by lactobacilli, enterococci, E coli, C perfringens or C difficile and has potential to be an applicable carbohydrate to complement probiotic Bif longum strains in synbiotic combinations. © 2002 Society of Chemical Industry     

Shelf‐life characteristics of fresh oysters and ground beef as affected by bacteriocin‐coated plastic packaging film

Fresh oysters and ground beef were wrapped in antimicrobial films coated with a bacteriocin (nisin or lacticin NK24) incorporated into a polyamide binder layer. The packaged foods were stored at 3 and 10 °C and changes in counts of total aerobic bacteria and coliform bacteria were monitored together with appropriate quality attributes in order to determine the influence of the bacteriocin‐coated films on quality preservation and shelf‐life extension. Compared to plain low‐density polyethylene film, plastic films with incorporated bacteriocins slowed down microbial growth on packaged oysters and ground beef at both temperatures, contributed in some degree to the preservation of chemical quality and extended shelf‐life significantly. The effects of the antimicrobial films on the suppression of coliform bacterial growth were more pronounced at 10 than at 3 °C , while the effects on total aerobic bacteria were consistently evident at both temperatures. There was no difference in food quality preservation between the two types of antimicrobial film. © 2002 Society of Chemical Industry     

Development of a process for producing ethyl caproate‐ and ethyl lactate‐rich rice shochu

To increase the popularity of rice shochu, a process was developed to produce ethyl caproate‐ and ethyl lactate‐rich rice shochu. On a laboratory‐scale, there was a shochu production trial with Saccharomyces cerevisiae Y‐E. Caproic acid added in the second‐stage fermentation was esterified to ethyl caproate. Both ethyl caproate and ethyl lactate were produced by adding a caproic acid‐producing bacterial (CAPB) consortium and lactic acid bacterium (LAB) to the shochu production process. Yellow koji was more appropriate for producing a flavour‐rich shochu with the addition of a CAPB consortium and LAB than white koji. Optimal addition time for the CAPB consortium and LAB was on the first day of the second‐stage fermentation, judging from concentrations of ethyl caproate and ethyl lactate produced. Additional dosages of CAPB consortium and LAB positively affected the formation of ethyl caproate and ethyl lactate, respectively. Shochu production with the addition of 2% and 4% CAPB consortium led to ethyl caproate concentrations of 27.3 mg/L and 47.9 mg/L in genshu, respectively, and the shochu achieved the best sensory test score from the Japanese shochu brewery panellists. Copyright © 2015 The Institute of Brewing & Distilling