The Monthly Digest – Food waste – July & August 2017

Food wastes and by-products
R & D abstracts – July & August 2017
Microbial processing of fruit and vegetable wastes into potential biocommodities: a review

The review focuses on some of the high value-end biocommodities, such as fermented beverages, single-cell proteins, single-cell oils, biocolors, flavors, fragrances, polysaccharides, biopesticides, plant growth regulators, bioethanol, biogas and biohydrogen, developed from the microbial processing of fruit and vegetable wastes. Microbial detoxification of fruit and vegetable processing effluents is briefly described. The advances in genetic engineering of microorganisms for enhanced yield of the above-mentioned biocommodities are elucidated with selected examples. The bottleneck in commercialization, integrated approach for improved production, techno-economic feasibility and real-life uses of some of these biocommodities, as well as research gaps and future directions are discussed.

Panda SK et al (2017) Critical Reviews in Biotechnology (in press)


Waste biorefineries: Enabling circular economies in developing countries (review)

This paper aims to examine the potential of waste biorefineries in developing countries as a solution to current waste disposal problems and as facilities to produce fuels, power, heat, and value-added products. The waste in developing countries represents a significant source of biomass, recycled materials, chemicals, energy, and revenue if wisely managed and used as a potential feedstock in various biorefinery technologies such as fermentation, anaerobic digestion (AD), pyrolysis, incineration, and gasification. However, the selection or integration of biorefinery technologies in any developing country should be based on its waste characterization. Waste biorefineries if developed in developing countries could provide energy generation, land savings, new businesses and consequent job creation, savings of landfills costs, GHG emissions reduction, and savings of natural resources of land, soil, and groundwater. The challenges in route to successful implementation of biorefinery concept in the developing countries are also presented using life cycle assessment (LCA) studies.

Nizami AS et al (2017) Bioresource Technology 241:1101-1117


Valorization of potato peel: a biorefinery approach (review)

Potato is the fourth main crop consumed worldwide and is an important constituent in the human diet. Consequently, potato is widely used in food-processing industries. However, these industries generate massive amounts of potato peel (PP) as a by-product, which is usually considered a waste, and is discarded. Interestingly, recent research suggests that PP is a valuable source of bioactive compounds, which can be converted into value-added products. In this study, we review the physicochemical composition and valorization of PP. In addition to being used as a dietary fiber or medicine, the value-added products obtained by the fermentation of PP have multiple uses, including their use as adsorbents, biocomposites and packaging materials. These products can also be used in energy production, biopolymer film development, corrosion inhibition and the synthesis of cellulose nanocrystals. The biorefinery approach for PP will increase the value of this waste by producing an array of value-added products and reducing extensive waste generation.

Pathak PD et al (2017) Critical Reviews in Biotechnology (in press)


Optimization of cultivation conditions in banana wastes for production of extracellular β-glucosidase by Trichoderma harzianum Rifai efficient for in vitro inhibition of Macrophomina phaseolina (research)

The present study was carried out to optimize the physical and nutritional parameters for cultivation of Trichoderma harzianum Rifai for production of extracellular β-glucosidase, an alternative to chemcial fungicides to control Macrophomina phaseolina, which causes charcoal rot disease in crops. Response surface methodology by the Box–Behnken design (BBD) based on four factors (temperature, carbon sources, inoculum size and pH) was used for optimization of the cultivation conditions to produce β-glucosidase using agro-industrial banana wastes. The highest β-glucosidase activity (1483.27 U/mL) was attained under optimized cultivation conditions: ∼36 ºC and pH 7.3, using carbon source and inoculum size of 10% (w/v) and 5% (w/v), respectively. It is noteworthy that the low deviation values (0.09−0.44%) in the verification experiments (R1, R2 and R3) inferred the generated model was accurate to predict optimal cultivation conditions of T. harzianumRifai. Likewise, the obtained diameters of inhibition zones ranging from 58.00−38.66 mm following treatment with β-glucosidase was found comparable to other in vitro tests using pure T. harzianum isolates and chemical fungicides. Hence, the findings indicated that it was feasible to use β-glucosidase as a greener alternative to chemical fungicides for control of M. phaseolina infection and consequently, for protection of crops against charcoal rot disease.

Khalili E et al (2017) Biotechnology & Biotechnological Equipment (in press)


Agrowaste to vanillin conversion by a natural Pediococcus acidilactici strain BD16 (research)

Owing to its flavoring, antimicrobial, antioxidant and anticarcinogenic nature, vanillin is widely used in foods, beverages, perfumes and pharmaceutical products. Ferulic acid (FA) is an important precursor of vanillin which is abundant in cereals like maize, rice and wheat and sugar beet. A major drawback of microbial vanillin production from FA is the degradation and biotransformation of toxic vanillin to other phenolic derivatives. The present study is undertaken to explore microbial vanillin production from FA precursor rice bran by employing vanillin-resistant Pediococcus acidilactici BD16, a natural lactic acid bacteria isolate. Extracellular, intracellular and cellular vanillin dehydrogenase activity was found least, which was minimized vanillin degradation, and the strain resists more than 5 g L−1 vanillin in the medium. A metabolomics approach was followed for the detection of FA, vanillin and other metabolites generated during fermentation of rice bran medium. A metabolic pathway was also predicted for vanillin biosynthesis. Approximately 1.06 g L−1 of crude vanillin was recovered from rice-bran-containing medium and this further offers scope for the industrial utilization of the organism and its genetic manipulation to enhance production of biovanillin.

Chakraborty D et al (2017) Environmental Technology 38:1823-1834


Potato peels: A potential food waste for amylase production (research)

In the present study, thermophilic and amylase producing bacterium Bacillus subtilis K-18 (KX881940) was isolated from local environment and identified by 16S rRNA gene sequencing technology. The amylase producing potential was checked by starch hydrolysis test using potato peels as carbon source. Central composite design (CCD) of response surface methodology (RSM) was used to optimize multiple process parameters such as substrate concentration, inoculum size, yeast extract, and pH. The optimized conditions obtained from RSM model were substrate concentration (2%), inoculum size (4%), yeast extract concentration (0.6%), and pH (5) yielding amylase activity of 1394.145 IU/ml after 24 hr of fermentation period at 50 °C. The maximum saccharification by indigenously produced amylase was 32.03% after 24 hr of incubation. The results confirmed that amylase produced by this newly isolated Bacillus subtilis K-18 (KX881940) could be potent strain for industrial process particular for biofuel production. The enzyme produced in this study could be effectively used in hydrolysis of starch to produce sugars which could be widely used for the production of various chemicals such ethanol and other products through fermentation. This enzyme also has potential application in textile industry.

Mushtaq Q et al (2017) Journal of Food Process Engineering 40 (in press)


Minimally processed beetroot waste as an alternative source to obtain functional ingredients (research)

Large amounts of waste are generated by the minimally processed vegetables industry, such as those from beetroot processing. The aim of this study was to determine the best method to obtain flour from minimally processed beetroot waste dried at different temperatures, besides producing a colorant from such waste and assessing its stability along 45 days. Beetroot waste dried at 70 °C originates flour with significant antioxidant activity and higher betalain content than flour produced from waste dried at 60 and 80 °C, while chlorination had no impact on the process since microbiological results were consistent for its application. The colorant obtained from beetroot waste showed color stability for 20 days and potential antioxidant activity over the analysis period, thus it can be used as a functional additive to improve nutritional characteristics and appearance of food products. These results are promising since minimally processed beetroot waste can be used as an alternative source of natural and functional ingredients with high antioxidant activity and betalain content.

Porto Dalla Costa A et al (2017) Journal of Food Science and Technology 54:2050-2058


Comparison of the anaerobic digestion at the mesophilic and thermophilic temperature regime of organic wastes from the agribusiness (research)

An overall kinetic power law model has been successfully applied to study the anaerobic digestion of agricultural wastes. In this comparative kinetic study feed composition, organic load rate, residence time and process temperature have been systematically varied in an automated semi-continuous fermentation system to obtain the dependency of the rate of degradation as biogas production on the organic load rate and temperature. The results show that the overall reaction order depend only on the Chemical Oxygen Demand (COD) at values between 3.6 and 3.7. The Arrhenius approach shows a shift in the rate determining step between the mesophilic and thermophilic temperature regimes. The activation energy at the temperature insensitive mesophilic regime is very small at 8.9 (kJ/mole), while the activation energy at the temperature sensitive thermophilic regime lies around 117 (kJ/mole).

Almeida Streitwieser D (2017) Bioresource Technology 241:985-982