Enhanced lipid and starch productivity of microalga (Chlorococcum sp. TISTR 8583) with nitrogen limitation following effective pretreatments for biofuel production

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To enhance the lipid and starch productivity of Chlorococcum sp. TISTR 8583 for biofuel productions.

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To identify suitable pretreatment strategy for release of fermentable sugars and lipids extraction from algal biomass.

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To convert the released fermentable sugars and lipids into bioethanol and biodiesel respectively.

The study was conducted to evaluate the conditions to enhance the accumulation of lipids and starch in Chlorococcum sp. TISTR 8583 for the production of biofuel. The Chlorococcum sp. TISTR 8583 was cultivated on BG-11 medium under optimized light intensity. The nitrogen limitation (NL) enhanced the accumulation of both starch and lipids and resulted in 34.02% total sugars as compared to 22.57% on nitrogen supplemented (NS) media only. Similarly, the nitrogen supplemented (NS) media produced 17.05% lipids as compared to 29.59% lipids by NL media. The biomass was investigated for biodiesel and bioethanol production by adopting different pretreatment strategies, such as enzyme, acid and alkaline pretreatments. The alkaline pretreatment was found to be efficient strategy (23.67 wt% sugars/g algal biomass: 1.2% (w/v) at 140 ⁰C for 30 min) while the acid pretreatment (1%: v/v; 140 °C) was least effective pretreatment strategy with the yield of 14.83 wt% sugars/g algal biomass.

Ochratoxin A detection in coffee by competitive inhibition assay using chitosan-based surface plasmon resonance compact system

This study demonstrates the evaluation of ochratoxin A (OTA) in coffee on compact surface plasmon resonance (SPR) biosensors based on crosslinked chitosan and carboxymethyl chitosan nanomatrix substrates. Ochratoxin A is a toxic secondary metabolite widely produced by Aspergillus and Penicillium fungi and requires regular quantification and detection in food samples. The gold coated SPR chips were synthesized with chitosan and carboxymethyl chitosan through spin coating technique. The SPR nanomatrix chips were used for the immobilization of ochratoxin A-bovine serum albumin (OTA-BSA) conjugate to develop a competitive inhibition immunoassay. The monoclonal ochratoxin A antibodies (mAb-OTA) were used as biological receptors for the detection of OTA in buffer and coffee samples. The limit of detection (LOD) in coffee for chitosan (CS) and carboxymethyl chitosan (CMC) substrates was 5.7 ng/mL and 3.8 ng/mL, respectively. Compact surface plasmon resonance (SPR) system based on chitosan-based (CS-AU) nanomatrix substrates provides a platform for the detection of ochratoxin A with high sensitivity, accuracy, ease-of-use and cost-effectiveness. This compact SPR system can be used at farm and industrial levels for the detection of OTA in food matrices.

Prospects for Food Fermentation in South-East Asia, Topics From the Tropical Fermentation and Biotechnology Network at the End of the AsiFood Erasmus+Project

Fermentation has been used for centuries to produce food in South-East Asia and some foods of this region are famous in the whole world. However, in the twenty first century, issues like food safety and quality must be addressed in a world changing from local business to globalization. In Western countries, the answer to these questions has been made through hygienisation, generalization of the use of starters, specialization of agriculture and use of long-distance transportation. This may have resulted in a loss in the taste and typicity of the products, in an extensive use of antibiotics and other chemicals and eventually, in a loss in the confidence of consumers to the products. The challenges awaiting fermentation in South-East Asia are thus to improve safety and quality in a sustainable system producing tasty and typical fermented products and valorising by-products. At the end of the “AsiFood Erasmus+ project” (www.asifood.org), the goal of this paper is to present and discuss these challenges as addressed by the Tropical Fermentation Network, a group of researchers from universities, research centers and companies in Asia and Europe. This paper presents current actions and prospects on hygienic, environmental, sensorial and nutritional qualities of traditional fermented food including screening of functional bacteria and starters, food safety strategies, research for new antimicrobial compounds, development of more sustainable fermentations and valorisation of by-products. A specificity of this network is also the multidisciplinary approach dealing with microbiology, food, chemical, sensorial, and genetic analyses, biotechnology, food supply chain, consumers and ethnology.

Culled banana resistant starch-soy protein isolate conjugate based emulsion enriched with astaxanthin to enhance its stability

The conjugates of biomacromolecules such as proteins and polysaccharides have potential to stabilize the emulsion system and encapsulate valuable bioactive compounds for biofortification in food systems. In this study, native banana starch (NBS) was isolated from green culled banana and modified into resistant starch (type III) by lintnerization followed by autoclaving-cooling process, resulting in lintnerized-autoclaved banana starch (LABS). Soy protein isolate (SPI) was used for developing the polysaccharide-protein conjugates i.e. LABS-SPI conjugate and used as wall material to stabilize the oil-in-water emulsion system. LABS-SPI conjugate emulsions were subjected to in vitro digestion model and oxidative stability evaluation. Furthermore, the emulsion system was enriched with astaxanthin and evaluated for its stability. The chemical finger printing of LABS-SPI conjugates showed stretching in immine and enaminol group of Schiff's bases, the CN stretching of Amadori product. During in vitro digestion LABS-SPI conjugate emulsion showed that the presence of resistant starch had an influence on the droplet digestion process and significantly (p < 0.05) lower free fatty acid release compared to emulsions stabilized by SPI alone. LABS-SPI conjugate emulsion system demonstrated higher stability of astaxanthin at storage temperatures (6, 20 and 37 °C), and can be used for biofortification of food and pharmaceutical formulations.

Experimental investigation on biochemical, microbial and sensory properties of Nile tilapia (Oreochromis niloticus) treated with moringa (Moringa oleifera) leaves powder

Six storage trials were conducted for preservation of Nile tilapia (Oreochromis niloticus) in ice storage at 5 °C using moringa leaves powder. The study aims to prolong the storage life of tilapia fish using moringa leaves powder of different concentrations. The effect of the moringa leaves powder (MLP) on biochemical, microbiological and sensory properties of fresh Nile tilapia stored in ice at 5 °C was investigated. Total volatile basic nitrogen, pH and thiobarbituric acid reactive substances values in MLP treated tilapia fish were 18.18 mg/100 g, 6.57, 5.63 mg MDA/kg respectively, which were significantly lower compared to untreated fish. Bacterial count (total viable count) was delayed significantly by increasing MLP concentration. The treated sample remains acceptable during storage in ice at 5 °C up to 11 days, whereas shelf life of untreated sample of tilapia was not extended beyond 7 days. The corresponding microbiological assessment also supports the results of sensory assessment that increased in shelf-life. The results revealed that the MLP is natural preservatives for extending the shelf life of Nile tilapia during transportation and ice storage.

Reinforced cassava starch based edible film incorporated with essential oil and sodium bentonite nanoclay as food packaging material

Biodegradable packaging in food materials is a green technology based novel approach to replace the synthetic and conventional packaging systems. This study is aimed to formulate the biodegradable cassava starch based films incorporated with cinnamon essential oil and sodium bentonite clay nanoparticles. The films were characterized for their application as a packaging material for meatballs. The cassava starch films incorporated with sodium bentonite and cinnamon oil showed significant antibacterial potential against all test bacteria; Escherichia coli, Salmonella typhimurium and Staphylococcus aureus. Antibacterial effect of films increased significantly when the concentration of cinnamon oil was increased. The cassava starch film incorporated with 0.75% (w/w) sodium bentonite, 2% (w/w) glycerol and 2.5% (w/w) cinnamon oil was selected based on physical, mechanical and antibacterial potential to evaluate shelf life of meatballs. The meatballs stored at ambient temperature in cassava starch film incorporated with cinnamon oil and nanoclay, significantly inhibited the microbial growth till 96 h below the FDA limits (10⁶ CFU/g) in foods compared to control films that exceeded above the limit within 48 h. Hence cassava starch based film incorporated with essential oils and clay nanoparticles can be an alternate approach as a packaging material for food industries to prolong the shelf life of products.

Extraction and characterization of proteins from banana (Musa Sapientum L) flower and evaluation of antimicrobial activities

Ultrasonic assisted alkaline extraction of protein from banana flower was optimized using response surface methodology. The extracted proteins were characterized by Fourier transform infrared spectroscopy and molecular weight distribution was determined by gel electrophoresis. The maximum protein yield of 252.25 mg/g was obtained under optimized extraction conditions: temperature 50 °C, 30 min extraction time and 1 M NaOH concentration. The alkaline extraction produced a significantly high protein yield compared to enzymatic extraction of banana flower. Chemical finger printing of proteins showed the presence of tyrosine, tryptophan and amide bonds in extracted protein. Alkaline and pepsin assisted extracted banana flower proteins showed characteristic bands at 40 and 10 kDA, respectively. The extracted proteins showed antibacterial effects against both gram positive and gram negative bacteria. The high protein content and antimicrobial activity indicate the potential applications of banana flower in the food and feed industry.

Screening of antibiotic residues in fresh milk of Kathmandu Valley, Nepal

The prevalence of two groups of antibiotics; namely penicillin and sulfonamides was studied in fresh milk available in Kathmandu Valley of Nepal. The milk samples (n = 140) were collected from three different sources; individual farmers, cottage dairies and organized dairies of Kathmandu valley. Qualitative and semi-quantitative analysis with rapid screening kits revealed that 23% samples were positive for antibiotic residues in the fresh milk for penicillin and sulfonamide groups (1-256 µg/kg). High performance liquid chromatography (HPLC) analyses detected 81% samples positive for amoxicillin (68-802 µg/kg), 41% for sulfadimethoxine (31-69 µg/kg), 27% for penicillin G (13-353 µg/kg), and 12% for ampicillin (0.5-92 µg/kg). Due to the precision and accuracy of liquid chromatography method, it detected more positive samples and consequently presented higher prevalence than the rapid screening kits. The antibiotic residues were found above the maximum residue limits that presented serious threat to consumer health and raised a serious concern regarding the implementation and monitoring of international regulations in developing countries.

Preparation of eggshell membrane protein hydrolysates and culled banana resistant starch-based emulsions and evaluation of their stability and behavior in simulated gastrointestinal fluids

This study aims to evaluate the effect of resistant starch (RS) derived from culled banana on the stability and characteristics of emulsions stabilized by eggshell membrane (ESM) protein hydrolysates. It was observed that incorporation of resistant starch improved the properties of the emulsions. Furthermore, the most stable emulsions developed (using a combination of RS and pretreated alcalase hydrolysates) were assessed for their behavior in an in-vitro gastrointestinal model system and changes in their particle size, zeta potential and morphology were evaluated. It was seen that these emulsions underwent flocculation and coalescence in the presence of pepsin and at higher concentrations of mucin enzyme and further coalescence and fatty acid release were observed after their passage through the small intestine. These insightful results about emulsion behavior in the gastrointestinal tract can be useful for designing delivery systems for controlled release of bioactive compounds.

Production and characterization of functional properties of protein hydrolysates from egg shell membranes by lactic acid bacteria fermentation

This study aimed to ferment the chicken eggshell membrane (ESM) using the lactic acid bacteria, Lactobacillus plantarum for preparation of functional and bioactive protein hydrolysates. Cultivation at an initial pH of 8.0 for 36 h resulted in maximum protein concentration (177.3 mg/g) and degree of hydrolysis (25.1%) of the hydrolysates. Fermentation resulted in the production of hydrolysates that demonstrated excellent solubility (90.7%), good foaming capacity (36.7%) and emulsification activity (94.6 m2/g). Additionally, these protein hydrolysates exhibited remarkable bioactive properties for instance reducing power (2.53), protection from DPPH radical (70.5%) and angiotensin I converting enzyme inhibition (49.3%). The fermented protein hydrolysates were also found effective against various foodborne pathogens. The protein hydrolysates obtained by fermentation of ESM can be potentially incorporated in functional foods and nutraceuticals resulting in valorization of the ESM waste.

Prevalence and antibiogram study of Salmonella and Staphylococcus aureus in poultry meat

OBJECTIVE

To evaluate the presence and antibiogram pattern of Salmonella and Staphylococcus aureus (S. aureus) in retail poultry meat products.

METHODS

Foodborne pathogens (Salmonella and S. aureus) were isolated from poultry meat and confirmed with the help of biochemical and immunological test. Antibiogram of the isolates were examined by following CLSI methods.

RESULTS

A total number of 209 poultry meat samples were collected and studied in this study. Out of which, 5.26% were found contaminated with Salmonella while 18.18% were found contaminated with S. aureus. All the Salmonella and S. aureus isolates were found resistant to at least one antibiotic. About 72.72% of the Salmonella isolates showed resistance to tetracycline, while S. aureus isolates were also found highly resistant to tetracycline equal to 44.73%. One of the Salmonella isolates showed multi-drug resistance to almost six antibiotics out of nine antibiotics used in the study. Multidrug resistant S. aureus isolates were also found in the study.

CONCLUSIONS

The study confirmed the presence of Salmonella and S. aureus in retail poultry meat. It is a potential threat to consumer health. To reduce the risk of contamination, good hygiene practices are necessary from processing to storage.

Enhanced oxidative stability of fish oil by encapsulating in culled banana resistant starch-soy protein isolate based microcapsules in functional bakery products

Oil in water emulsions were produced by the mixture of culled banana resistant starch (CBRS) & soy protein isolate (SPI), mixture of Hylon VII & SPI and SPI with 7.5 and 5 % (w/w) Menhaden fish oil. The emulsions were further freeze- dried obtaining 33 and 50 % oil load microcapsules. The range of particles diameter was 4.11 to 7.25 μm and viscosity was 34.6 to 146.48 cP of the emulsions. Compressibility index (CI), Hasner ratio (HR) and angle of repose (AR) was significantly (p < 0.01) lower of the microcapsules made with starch and protein (CBRS & SPI and Hylon VII & SPI) than that made with protein (SPI) only. Microcapsules composed of CBRS & SPI with 33 % oil load had maximum microencapsulation efficiency (82.49 %) and highest oxidative stability. Muffin made with emulsions containing mixture of CBRS & SPI exhibited less fishy flavour than that containing mixture of Hylon VII & SPI.