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Polyhydroxyalkanoates (PHA) envisage a potential biomaterial alternative to replacing synthetic polymers for their biodegradability and biocompatibility. Modification approaches exploit the attributes and adjust the intrinsic hydrophobic properties, such as blending to produce a new polymer mix with novel properties. Functionalization of PHA, especially chemical grafting, perform to introduce additional compounds covalently to PHA. As these methods address PHA potential and enable extensive utilization as a responsive material, reports are readily available in academia as confirmation. There are also substantial responsive PHA-based material applications in the biomedical area and agriculture materials, packaging materials, and nanocomposite materials.

Background A more frequent consumption of deep-fat fried food is believed to be linked with a higher risk of subsequently developing obesity and higher severe diseases. However, the evidence from long-term randomized trials or prospective epidemiological studies is scarce. Dietary management for a healthier consumption of food with low fat intake gives high contributions to health. Scope and approach Despite the changes in lifestyle that acquire more favourable type of deep-fat fried food as the main dish, a dietary fibre-formulated batter could be the most suitable substitute without changing the taste to keep the health benefits within. Dietary fibre-formulated batter consists the same benefits as resistant starch that can reduce the blood cholesterol level, the glycaemic index and influence in digestive tract. In this review paper, we discuss the factors, properties, background and applications of fibres in batter formulations for oil uptake reduction. Key findings and conclusions With high potential of health benefits, different types of dietary fibre have been explored as batter formulations. Dietary fibres are proven to reduce the oil uptake of fried food products as well as improving the textural and overall acceptability. The application of dietary fibre as batter rich in nutrients could be product-friendly for deep-fat fried food products.

Active food packaging is currently of high demand in food industries to provide protections to food. Food packaging is not only used to store and protect food from the environment, but also to provide functional values with the incorporation of active agent. Essential oils (EOs) extracted from a variety of plants represent active ingredients of natural origin which provide numerous benefits to food, aromatherapy, pharmaceutical, and food packaging industries due to their functional properties. Numerous researches have been carried out in developing active food packaging such as insect repellent packaging containing essential oils. Insect repellent packaging could create safety measures by repelling insect from exterior environment or the inhibition of larvae from food within. In this paper, different application of EOs on different types of food packaging, applications, processing methods, migration of active compounds and performance of insect repellency are reviewed. Future perspectives and applications of insect repellence using safe, natural and more effective strategies are also discussed. EOs as the active insect repellent agents in food packaging offer great opportunities to protect the quality of food. Some important factors such as legislative concerns (e.g. toxicity test, migration of active substances from packaging materials), economics, and further study on the release period of active agent to the environment should be considered to successfully implement insect repellent agents in food packaging.

Polysaccharides from the natural sources are gaining increasing keen from researchers as components of stimuli responsive in drug delivery systems. Polysaccharides are intrinsically biocompatible because the similitude of their structure with many body components and readily degradable in environment by common microorganisms. Ionic polysaccharides can be readily cross-linked to provide hydrogel networks sensitive to a diverse of internal and external variables and thus suitable for switching drug release on-off through various mechanisms for floating drug delivery system inside the gastrointestinal tract. Moreover, the application of polysaccharides gelled into floating drug delivery systems improves the drug bioavailability and patient compliance by increasing the gastric residence time and controlling the drug release. This chapter described the adaptation of drug delivery system by using ionically gelled polysaccharides-based floating drug delivery system inside the gastrointestinal tract.

Biosynthesis and in vivo depolymerization of intracellular medium-chain-length poly-3-hydroxyalkanoates (mcl-PHA) in Pseudomonas putida Bet001 grown on lauric acid were studied. Highest mcl-PHA fraction (>50 % of total biomass) and cell concentration (8 g L-1 ) were obtained at carbon-to-nitrogen (C/N) ratio 20, starting cell concentration 1 g L-1 , and 48 H fermentation. The mcl-PHA comprised of 3-hydroxyhexanoate (C6 ), 3-hydroxyoctanote (C8 ), 3-hydroxydecanoate (C10 ), and 3-hydroxydodecanoate (C12 ) monomers. In vivo action was studied in a mineral liquid medium without carbon source, and in different buffer solutions with varied pH, molarity, ionic strength, and temperature. The monomer liberation rate reflected the mol percentage distribution of the initial polymer subunit composition. Rate and percentage of in vivo depolymerization were highest in 0.2 M Tris-HCl buffer (pH 9, strength = 0.2 M, 30 °C) at 0.21 g L-1 H-1 and 98.6 ± 1.3 wt%, respectively. There is a congruity vis-a-vis to specific buffer type, molarity, pH, ionic strength, and temperature values for superior in vivo depolymerization activities. Direct products from in vivo depolymerization matched the individual monomeric composition of native mcl-PHA. It points to exo-type reaction for the in vivo process, and potential biological route to chiral molecules.

Pseudomonas putida Bet001 and Delftia tsuruhatensis Bet002, isolated from palm oil mill effluent, accumulated poly(3-hydroxyalkanoates) (PHAs) when grown on aliphatic fatty acids, sugars, and glycerol. The substrates were supplied at 20:1 C/N mole ratio. Among C-even n-alkanoic acids, myristic acid gave the highest PHA content 26 and 28 wt% in P. putida and D. tsuruhatensis, respectively. Among C-odd n-alkanoic acids, undecanoic gave the highest PHA content at 40 wt% in P. putida and 46 wt% in D. tsuruhatensis on pentadecanoic acid. Sugar and glycerol gave

In vivo and in vitro depolymerizations of intracellular medium-chain-length poly-3-hydroxyalkanoates (mcl-PHA) in Pseudomonas putida Bet001 grown on lauric acid was studied. Both processes were studied under optimum conditions for mcl-PHA depolymerization viz. 0.2 M Tris-HCl buffer, pH 9, ionic strength (I) = 0.2 M at 30 °C. For in vitro depolymerization studies, cell-free system was obtained from lysing bacterial cells suspension by ultrasonication at optimum conditions (frequency 37 kHz, 30% of power output, °C for 120 minutes). The comparison between in vivo and in vitro depolymerizations of intracellular mcl-PHA was made. In vitro depolymerization showed lower depolymerization rate but higher yield compared to in vivo depolymerization. The monomer liberation rate reflected the mol percentage distribution of the initial polymer subunit composition, and the resulting direct individual products of depolymerization were identical for both in vivo and in vitro processes. It points to exo-type reaction for both processes, and potential biological route to chiral molecules.

Wound management and healing in several physiological or pathological conditions, particularly when comorbidities are involved, usually proves to be difficult. This presents complications leading to socio-economic and public health burdens. The accelerative wound healing potential of biocompatible poly(3-hydroxyalkanoates)-co-(6-hydroxyhexanoate) (PHA-PCL) composite hydrogel is reported herein. The biosynthesized PHA-PCL macromer was cross-linked with PEGMA to give a hydrogel. Twenty-four rats weighing 200-250 g each were randomly assigned to four groups of six rats. Rats in group I (negative control) were dressed with sterilized gum acacia paste in 10% normal saline while PEGMA-alone hydrogel (PH) was used to dress group II (secondary control) rats. Group III rats were dressed with PHAs-PCL cross-linked PEGMA hydrogel (PPH). For the positive control (group IV), the rats were dressed with Intrasite(®) gel. Biochemical, histomorphometric and immunohistomorphometric analyses revealed a significant difference in area closure and re-epithelialization on days 7 and 14 in PPH or Intrasite(®) gel groups compared to gum acacia or PEGMA-alone groups. Furthermore, wounds dressed with PPH or Intrasite(®) gel showed evident collagen deposition, enhanced fibrosis and extensively organized angiogenesis on day 14 compared to the negative control group. While improvement in wound healing of the PH dressed group could be observed, there was no significant difference between the negative control group and the PH dressed group in any of the tests. The findings suggested that topical application of PPH accelerated the rats' wound healing process by improving angiogenesis attributed to the increased microvessel density (MVD) and expressions of VEGF-A in tissue samples. Thus, PPH has been demonstrated to be effective in the treatment of cutaneous wounds in rats, and could be a potential novel agent in the management and acceleration of wound healing in humans and animals.

Pseudomonas putida Bet001 and Delftia tsuruhatensis Bet002, isolated from palm oil mill effluent, accumulated poly(3-hydroxyalkanoates) (PHAs) when grown on aliphatic fatty acids, sugars, and glycerol. The substrates were supplied at 20:1 C/N mole ratio. Among C-even n-alkanoic acids, myristic acid gave the highest PHA content 26 and 28 wt% in P. putida and D. tsuruhatensis, respectively. Among C-odd n-alkanoic acids, undecanoic gave the highest PHA content at 40 wt% in P. putida and 46 wt% in D. tsuruhatensis on pentadecanoic acid. Sugar and glycerol gave10 wt% of PHA content for both bacteria. Interestingly, D. tsuruhatensis accumulated both short- and medium-chain length PHA when supplied with n-alkanoic acids ranging from octanoic to lauric, sucrose, and glycerol with 3-hydroxybutyrate as the major monomer unit. In P. putida, the major hydroxyalkanoates unit was 3-hydroxyoctanoate and 3-hydroxydecanoate when grown on C-even acids. Conversely, 3-hydroxyheptanoate, 3-hydrxoynonanoate, and 3-hydroxyundecanoate were accumulated with C-odd acids. Weight-averaged molecular weight (M

A simple procedure for recovering biodegradable polymer from bacterial cells has been developed using economical and environmentally friendly solvent or chemicals. Recombinant bacterium, Cupriavidus necator harboring pBBR1MCS-C2 plasmid polyhydroxyalkanoate (PHA) synthase gene was used for the production of copolymer P(3HB-co-3HHx) from crude palm kernel oil (CPKO). NaOH was chosen in this study as it could give high purity and recovery yield. Increase of NaOH concentration had resulted in an increase of the PHA purity, but the recovery yield had decreased. The greater improvement of PHA purity and recovery were achieved by incubating the freeze-dried cells (10–30 g/L) in NaOH (0.1 M) for 1–3 h at 30°C and polishing using 20% (v/v) of ethanol. The treatment caused negligible degradation of the molecular weight of PHA recovered from the bacterial cells. The present review also highlights other extraction methods to provide greater insights into economical and sustainable recovery of PHA from bacterial cells.

A simple, efficient and economical method for the recovery of P(3HB-co-3HHx) was developed using various chemicals and parameters. The initial content of P(3HB-co-3HHx) in bacterial cells was 50–60 wt%, whereas the monomer composition of 3HHx used in this experiments was 3–5 mol%. It was found that sodium hydroxide (NaOH) was the most effective chemical for the recovery of biodegradable polymer. High polyhydroxyalkanoate purity and recovery yield both in the range of 80–90 wt% were obtained when 10–30 mg/ml of cells were incubated in NaOH at the concentration of 0.1 M for 60–180 min at 30 °C and polished using 20 % (v/v) of ethanol.