The by-products produced from fruit processing industries could be a potential hazard to environmental pollution. However, these by-products contain several biologically active molecules (essential fatty acid, phenolic compounds, flavonoids, coloring pigments, pectin, proteins, dietary fibers, and vitamins), which can be utilized for various applications in the food, pharmaceutical, cosmetic and textile industries. Nevertheless, during extraction, these bioactive compounds' recovery must be maximized using proper extraction technologies, keeping both economy and environment under consideration. In addition, the characteristics of the extract obtained from those by-products depend mainly on the parameters considered during the extraction process. In this review, an overview of different technologies used to extract bioactive compounds from fruit industry by-products such as seeds and peels has been briefly discussed, along with their mechanisms, process, advantages, disadvantages, and process parameters. In addition, the characteristics of the extracted bioactive compounds have also been briefly discussed in this review. Graphical Abstract

This study explores the effect of ultra-sonication on the extraction of phenolic compounds of cashew apple bagasse (CAB). The extraction was conducted at different combinations of treatment time (5-15 min), ultrasound amplitude (30-60%), and bagasse to solvent ratio (30-50 g/ml) for maximum yield of total phenolic content (TPC), total tannin content (TTC), and β-carotene content. Both response surface methodology (RSM) and artificial neural network (ANN) were used to model and optimize the process parameters. The optimum conditions achieved using RSM were: treatment time of 12 min, ultrasound amplitude of 55%, and bagasse to solvent ratio of 45 g/ml. In contrast, the optimum conditions proposed by ANN were: treatment time of 15 min, 60% amplitude, and 50 g/ml bagasse to solvent ratio. The TPC, TTC, and β-carotene content was determined under RSM optimized conditions as 29.04 mg GAE/g, 26.70 μg tannic acid/g, and 18.12 μg/g, respectively and under ANN optimized conditions as 30.61 mg GAE/g, 30.80 μg tannic acid/g, and 19.50 μg/ g, respectively. All the statistical parameters showed the lowest value in the ANN model than the RSM model with the highest coefficient of determination (R 2 ). The measured value of the TPC, TTC, and β-carotene content at optimized conditions were in agreement with the predicted value obtained from the above models. Besides these, the ultra-sonication significantly increased the TPC, TTC, and β-carotene content while comparing with conventional solvent extraction. Hence, this method could be an effective green method over conventional technologies to extract phenolic compounds from CAB.

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In the present study a comprehensive review on rheological characteristics of nanofluids for their advanced heat transfer applications has been conducted and presented. The present article critically summarizes the recent research developments regarding the theoretical and experimental investigations about viscosity of different nanofluids. In addition, different reasonably attractive theoretical models and experimental correlations are explored and well discussed. Moreover, the current study analyzes several factors those strongly influencing viscosity of nanofluids include solid volume fraction, temperature, particle size, particle shape, different base fluids, surfactants addition, ultrasonication, nanoclustering and pH value. Important theoretical and experimental results from many researchers and predictions from a number of viscosity models are compared and discussed with appropriate justification. Most results reveal that the viscosity of nanofluid upsurges due to an increase in particle concentration while that belittles with diminishing temperature. Augmentation of nano-additives size leads to decreasing/increasing of nanofluid fluid viscosity. For the most nanofluids, Newtonian behavior is observed for low volume fractions, shear rates, concentrations and viscosity while non-Newtonian behavior is visualized for high volume fractions, shear rates, concentrations and viscosity. Nanofluids used carbon nanotubes are almost non-Newtonian in nature while nanofluids not involving carbon nanotubes are mostly Newtonian. Finally, the research challenges and needs in this important area of nanofluids are also highlighted.

The cashew apple (Anacardium occidentale L.) is a pseudo fruit of cashew grown principally in the tropical regions of Brazil, Guyana, Madagascar, India, and Vietnam, and its production represents 1.1% of the world's exotic fruits production (Mathew et al., 2011).According to FAOSTAT (2019), about 1.32 million metric tons of cashew apples have been produced worldwide, whereas India has been producing about 60 lakh tons of fruit per year. Its peduncle possesses about 60%-90% of the total fruit weight (Singh et al., 2019). Cashew apples are a rich source of ascorbic acid, phenolic compounds, and natural antioxidants. The cashew apple bagasse (CAB) is the by-product of these industries which produce fermented/non-fermented beverages, and confectioneries. The