Keshavan Niranjan - Academia.edu (original) (raw)
Papers by Keshavan Niranjan
Journal of Food Engineering
Foam properties depend on the physico-chemical characteristics of the continuous phase, the metho... more Foam properties depend on the physico-chemical characteristics of the continuous phase, the method of production and process conditions employed; however the preparation of barista-style milk foams in coffee shops by injection of steam uses milk as its main ingredient which limits the control of foam properties by changing the biochemical characteristics of the continuous phase. Therefore, the control of process conditions and nozzle design are the only ways available to produce foams with diverse properties. Milk foams were produced employing different steam pressures (100–280 kPa gauge) and nozzle designs (ejector, plunging-jet and confined-jet nozzles). The foamability of milk, and the stability, bubble size and texture of the foams were investigated. Variations in steam pressure and nozzle design changed the hydrodynamic conditions during foam production, resulting in foams having a range of properties. Steam pressure influenced foam characteristics, although the net effect depe...
Osmotic dehydration is gaining popularity due to several energy and product quality related advan... more Osmotic dehydration is gaining popularity due to several energy and product quality related advantages it offers. It has huge potential as a complementary process steps prior to operations such as air-drying, microwave drying, freezing, frying etc, if not an alternative one, in the food process chain. It can be easily integrated with other processing steps in order to improve the overall productivity of a given food process. Application of additional driving force either prior to or during osmotic dehydration can enhance the mass transfer rates in the osmotic dehydration. Role of mathematical modelling both in osmotic dehydration and rehydration have been discussed. Current limitations for the adaptation in the food processing industry and possible solutions are also discussed in detail.
Food Chemistry, 2015
This study investigates the effects of temperature and pressure on inactivation of myrosinase ext... more This study investigates the effects of temperature and pressure on inactivation of myrosinase extracted from black, brown and yellow mustard seeds. Brown mustard had higher myrosinase activity (2.75 un/mL) than black (1.50 un/mL) and yellow mustard (0.63 un/mL). The extent of enzyme inactivation increased with pressure (600-800 MPa) and temperature (30-70° C) for all the mustard seeds. However, at combinations of lower pressures (200-400 MPa) and high temperatures (60-80 °C), there was less inactivation. For example, application of 300 MPa and 70 °C for 10 min retained 20%, 80% and 65% activity in yellow, black and brown mustard, respectively, whereas the corresponding activity retentions when applying only heat (70° C, 10 min) were 0%, 59% and 35%. Thus, application of moderate pressures (200-400 MPa) can potentially be used to retain myrosinase activity needed for subsequent glucosinolate hydrolysis.
Osmotic dehydration can be considered as the most eligible energy saving method for the partial r... more Osmotic dehydration can be considered as the most eligible energy saving method for the partial removal of water from foods, if and even as a method of preservation in the case of candy preparation. It can affect marked reduction in the moisture content of the foods before they are subjected to further processing steps such as drying, freezing, frying, etc. The pretreatment with the osmotic solution having concentrations lower than the natural cell concentration can improve the rehydration characteristics. Osmotic dehydration can be used also for the natural concentration of fruits, which helps in obtaining better characteristics of food prepared from the same, such as jam. The application of various pretreatments to osmotic dehydration such as application of high hydrostatic pressure, high electrical field pulses, gamma irradiation, ultrasound, and vacuum and centrifugal force, can overcome the long-existing issues related to inherently slower mass transfer rates. The basic underst...
1,6-alpha-D-Mannosidase from Aspergillus phoenicis was purified by anion-exchange chromatography,... more 1,6-alpha-D-Mannosidase from Aspergillus phoenicis was purified by anion-exchange chromatography, chromatofocussing and size-exclusion chromatography. The apparent molecular weight was 74 kDa by SDS-PAGE and 81 kDa by native-PAGE. The isoelectric point was 4.6. 1,6-alpha-D-Mannosidase had a temperature optimum of 60 degrees C, a pH optimum of 4.0-4.5, a K(m) of 14 mM with alpha-D-Manp-(1-->6)-D-Manp as substrate. It was strongly inhibited by Mn(2+) and did not need Ca(2+) or any other metal cofactor of those tested. The enzyme cleaves specifically (1-->6)-linked mannobiose and has no activity towards any other linkages, p-nitrophenyl-alpha-D-mannopyranoside or baker's yeast mannan. 1,3(1,6)-alpha-D-Mannosidase from A. phoenicis was purified by anion-exchange chromatography, chromatofocussing and size-exclusion chromatography. The apparent molecular weight was 97 kDa by SDS-PAGE and 110 kDa by native-PAGE. The 1,3(1,6)-alpha-D-mannosidase enzyme existed as two charge isomers or isoforms. The isoelectric points of these were 4.3 and 4.8 by isoelectric focussing. It cleaves alpha-D-Manp-(1-->3)-D-Manp 10 times faster than alpha-D-Manp-(1-->6)-D-Manp, has very low activity towards p-nitrophenyl-alpha-D-mannopyranoside and baker's yeast mannan, and no activity towards alpha-D-Manp-(1-->2)-D-Manp. The activity towards (1-->3)-linked mannobiose is strongly activated by 1mM Ca(2+) and inhibited by 10mM EDTA, while (1-->6)-activity is unaffected, indicating that the two activities may be associated with different polypeptides. It is also possible that one polypeptide may have two active sites catalysing distinct activities.
... Sahin, S., & Sumnu, SG (2009). Introduction. In S. Sahin & SG Sumnu (Eds.), Advances ... more ... Sahin, S., & Sumnu, SG (2009). Introduction. In S. Sahin & SG Sumnu (Eds.), Advances in deep fat frying of foods (pp. 1–3). London: CRC Press. ... Food and Bioprocess Technology, 3(1), 71–78. Sila, DN, Smout, C., Vu, TS, & Hendrickx, ME (2004). ...
ABSTRACT This study proposes to incorporate an antifungal agent (potassium sorbate, KS) to post-c... more ABSTRACT This study proposes to incorporate an antifungal agent (potassium sorbate, KS) to post-consumer recycled polyethylene terephthalate (PCRPET), by adding KS to the dip solution through which PCRPET normally passes after extrusion, in order to acquire a non-stick silicone coating, which prevents individual packages from adhering to each other while stacked. This method of imparting antifungal activity to the packaging is far more advantageous than adding KS to the extruder feed because it results in virtually no alterations to the colour and mechanical properties of PCRPET, which is a major issue when KS is added to the extruder feed. The antifungal efficacy of the active packaging was demonstrated against Botrytis cinerea growth by a novel method which mimics the action of the antifungal agent under fruit contact conditions. A reduction by 2 log cycles was observed when the initial concentration of the mould was 105 conidia/mL. The active packaging was effective over a test period lasting 6 months. The packaging microstructure was visualized by scanning electron microscopy (SEM); its thermal properties were characterized using a differential scanning calorimeter (DSC); its optical properties were characterized using CIE Lab colorimetry; and its mechanical properties were characterized by measuring resistance to dynamic compression. The mechanical properties showed no significant difference (P > 0.05) with those of the control (PCRPET without KS), and despite a statistically significant difference (P < 0.05) in the colour parameters (L*, a* and b*), the total colour difference (ΔE*) was found to be too small to be visually noticed. This study achieved the aim of adding antifungal activity to PCRPET packaging with little or no perceptible changes to its mechanical, thermal and optical properties and virtually no changes being made to the standard high-speed packaging production line.
The Chemical Engineering Journal, 1984
ABSTRACT Packed bubble columns offer several advantages over bubble columns. For example, the gas... more ABSTRACT Packed bubble columns offer several advantages over bubble columns. For example, the gas holdup and mass transfer characteristics of packed bubble columns are superior to those of bubble columns, and the axial dispersion coefficient values are much lower.The gas holdup and mixing characteristics of a number of packings are considered in this article. An empirical equation is proposed to estimate the gas holdup values. The effects of the packing size, the column diameter, the liquid viscosity and the ionic strength on the gas holdup are discussed. The axial dispersion coefficient values for packings with nominal sizes of 0.025 m and above are correlated by means of a model based on the bulk liquid circulation in the column.
Journal of Food Science, 2015
Air frying is being projected as an alternative to deep fat frying for producing snacks such as F... more Air frying is being projected as an alternative to deep fat frying for producing snacks such as French fries. In air frying, the raw potato sections are essentially heated in hot air containing fine oil droplets, which dehydrates the potato and attempts to impart the characteristics of traditionally produced French fries, but with a substantially lower level of fat absorbed in the product. The aim of this research is to compare: (1) the process dynamics of air frying with conventional deep fat frying under otherwise similar operating conditions, and (2) the products formed by the 2 processes in terms of color, texture, microstructure, calorimetric properties, and sensory characteristics. Although, air frying produced products with a substantially lower fat content but with similar moisture contents and color characteristics, it required much longer processing times, typically 21 min in relation to 9 min in the case of deep fat frying. The slower evolution of temperature also resulted in lower rates of moisture loss and color development reactions. Differential scanning calorimetry (DSC) studies revealed that the extent of starch gelatinization was also lower in the case of air fried product. In addition, the 2 types of frying also resulted in products having significantly different texture and sensory characteristics.
Journal of Food Science, 2014
Fried products impose a health concerns due to considerable amount of oil they contain. Productio... more Fried products impose a health concerns due to considerable amount of oil they contain. Production of snack foods with minimal oil content and good management of oil during frying to minimize the production of toxic compounds continue to be challenging aims. This paper aims to investigate the possibility of producing a fat-free food snack by replacing frying oil with a nonfat medium. Glucose was melted and its temperature was then brought to 185 °C and used to fry potato strips, to obtain a product referred here as glucose fries. The resulting product was compared with French fries prepared conventionally under conditions that resulted in similar final moisture content. The resulting products were also examined for crust formation, texture parameters, color development and glucose content. Stereo microscope images showed that similar crusts were formed in the glucose fries and French fries. Texture parameters were found to be similar for both products at 5 and 2 mm penetration depth. The maximum hardness at 2 mm penetration depth was also similar for both products, but different from cooked potato. The color development that characterized French fries was also observed in glucose fries. The glucose content in glucose fries was found to be twice the content of French fries, which is to be expected because glucose absorbed or adhered to the surface. In conclusion, glucose fries, with similar texture and color characteristics to that of French fries, can be prepared by using a nonfat frying medium.
Trends in Food Science & Technology, 2015
ABSTRACT Regulatory, safety, and environmental issues have prompted the development of aqueous en... more ABSTRACT Regulatory, safety, and environmental issues have prompted the development of aqueous enzymatic extraction (AEE) for extracting components from oil-bearing materials. The emulsion resulting from AEE requires de-emulsification to separate the oil; when enzymes are used for this purpose, the method is known as aqueous enzymatic emulsion de-emulsification (AEED). In general, enzyme assisted oil extraction is known to yield oil having highly favourable characteristics. This review covers technological aspects of enzyme assisted oil extraction, and explores the quality characteristics of the oils obtained, focusing particularly on recent efforts undertaken to improve process economics by recovering and reusing enzymes.
Food Mixing, 2009
... Massey et al. 2001; Lau & Dickinson 2005; Jakubczyk & Niranjan 2006), where the dispe... more ... Massey et al. 2001; Lau & Dickinson 2005; Jakubczyk & Niranjan 2006), where the dispersion is stable and air release during the measurement process is negligible. In the ... Massey et al. 2001; Lau & Dickinson 2005). This trend ...
Food Materials Science, 2008
... Massey et al. 2001; Lau and Dickinson 2005; Jakubczyk and Niranjan 2006), where the dispersio... more ... Massey et al. 2001; Lau and Dickinson 2005; Jakubczyk and Niranjan 2006), where the dispersion is stable and air release during the measurement process is negligible. In the ... Massey et al. 2001; Lau and Dickinson 2005). This trend ...
Trends in Food Science & Technology, 2002
... advantages, is gaining popularity as a complimentary processing step in the chain of integrat... more ... advantages, is gaining popularity as a complimentary processing step in the chain of integratedfood processing. ... Various methods to increase the rate of mass transfer, such as application of high hydrostatic pressure, high electrical field pulses, ultrasound, vacuum and ...
Journal of Food Engineering
Foam properties depend on the physico-chemical characteristics of the continuous phase, the metho... more Foam properties depend on the physico-chemical characteristics of the continuous phase, the method of production and process conditions employed; however the preparation of barista-style milk foams in coffee shops by injection of steam uses milk as its main ingredient which limits the control of foam properties by changing the biochemical characteristics of the continuous phase. Therefore, the control of process conditions and nozzle design are the only ways available to produce foams with diverse properties. Milk foams were produced employing different steam pressures (100–280 kPa gauge) and nozzle designs (ejector, plunging-jet and confined-jet nozzles). The foamability of milk, and the stability, bubble size and texture of the foams were investigated. Variations in steam pressure and nozzle design changed the hydrodynamic conditions during foam production, resulting in foams having a range of properties. Steam pressure influenced foam characteristics, although the net effect depe...
Osmotic dehydration is gaining popularity due to several energy and product quality related advan... more Osmotic dehydration is gaining popularity due to several energy and product quality related advantages it offers. It has huge potential as a complementary process steps prior to operations such as air-drying, microwave drying, freezing, frying etc, if not an alternative one, in the food process chain. It can be easily integrated with other processing steps in order to improve the overall productivity of a given food process. Application of additional driving force either prior to or during osmotic dehydration can enhance the mass transfer rates in the osmotic dehydration. Role of mathematical modelling both in osmotic dehydration and rehydration have been discussed. Current limitations for the adaptation in the food processing industry and possible solutions are also discussed in detail.
Food Chemistry, 2015
This study investigates the effects of temperature and pressure on inactivation of myrosinase ext... more This study investigates the effects of temperature and pressure on inactivation of myrosinase extracted from black, brown and yellow mustard seeds. Brown mustard had higher myrosinase activity (2.75 un/mL) than black (1.50 un/mL) and yellow mustard (0.63 un/mL). The extent of enzyme inactivation increased with pressure (600-800 MPa) and temperature (30-70° C) for all the mustard seeds. However, at combinations of lower pressures (200-400 MPa) and high temperatures (60-80 °C), there was less inactivation. For example, application of 300 MPa and 70 °C for 10 min retained 20%, 80% and 65% activity in yellow, black and brown mustard, respectively, whereas the corresponding activity retentions when applying only heat (70° C, 10 min) were 0%, 59% and 35%. Thus, application of moderate pressures (200-400 MPa) can potentially be used to retain myrosinase activity needed for subsequent glucosinolate hydrolysis.
Osmotic dehydration can be considered as the most eligible energy saving method for the partial r... more Osmotic dehydration can be considered as the most eligible energy saving method for the partial removal of water from foods, if and even as a method of preservation in the case of candy preparation. It can affect marked reduction in the moisture content of the foods before they are subjected to further processing steps such as drying, freezing, frying, etc. The pretreatment with the osmotic solution having concentrations lower than the natural cell concentration can improve the rehydration characteristics. Osmotic dehydration can be used also for the natural concentration of fruits, which helps in obtaining better characteristics of food prepared from the same, such as jam. The application of various pretreatments to osmotic dehydration such as application of high hydrostatic pressure, high electrical field pulses, gamma irradiation, ultrasound, and vacuum and centrifugal force, can overcome the long-existing issues related to inherently slower mass transfer rates. The basic underst...
1,6-alpha-D-Mannosidase from Aspergillus phoenicis was purified by anion-exchange chromatography,... more 1,6-alpha-D-Mannosidase from Aspergillus phoenicis was purified by anion-exchange chromatography, chromatofocussing and size-exclusion chromatography. The apparent molecular weight was 74 kDa by SDS-PAGE and 81 kDa by native-PAGE. The isoelectric point was 4.6. 1,6-alpha-D-Mannosidase had a temperature optimum of 60 degrees C, a pH optimum of 4.0-4.5, a K(m) of 14 mM with alpha-D-Manp-(1--&amp;amp;amp;amp;amp;gt;6)-D-Manp as substrate. It was strongly inhibited by Mn(2+) and did not need Ca(2+) or any other metal cofactor of those tested. The enzyme cleaves specifically (1--&amp;amp;amp;amp;amp;gt;6)-linked mannobiose and has no activity towards any other linkages, p-nitrophenyl-alpha-D-mannopyranoside or baker&amp;amp;amp;amp;amp;#39;s yeast mannan. 1,3(1,6)-alpha-D-Mannosidase from A. phoenicis was purified by anion-exchange chromatography, chromatofocussing and size-exclusion chromatography. The apparent molecular weight was 97 kDa by SDS-PAGE and 110 kDa by native-PAGE. The 1,3(1,6)-alpha-D-mannosidase enzyme existed as two charge isomers or isoforms. The isoelectric points of these were 4.3 and 4.8 by isoelectric focussing. It cleaves alpha-D-Manp-(1--&amp;amp;amp;amp;amp;gt;3)-D-Manp 10 times faster than alpha-D-Manp-(1--&amp;amp;amp;amp;amp;gt;6)-D-Manp, has very low activity towards p-nitrophenyl-alpha-D-mannopyranoside and baker&amp;amp;amp;amp;amp;#39;s yeast mannan, and no activity towards alpha-D-Manp-(1--&amp;amp;amp;amp;amp;gt;2)-D-Manp. The activity towards (1--&amp;amp;amp;amp;amp;gt;3)-linked mannobiose is strongly activated by 1mM Ca(2+) and inhibited by 10mM EDTA, while (1--&amp;amp;amp;amp;amp;gt;6)-activity is unaffected, indicating that the two activities may be associated with different polypeptides. It is also possible that one polypeptide may have two active sites catalysing distinct activities.
... Sahin, S., & Sumnu, SG (2009). Introduction. In S. Sahin & SG Sumnu (Eds.), Advances ... more ... Sahin, S., & Sumnu, SG (2009). Introduction. In S. Sahin & SG Sumnu (Eds.), Advances in deep fat frying of foods (pp. 1–3). London: CRC Press. ... Food and Bioprocess Technology, 3(1), 71–78. Sila, DN, Smout, C., Vu, TS, & Hendrickx, ME (2004). ...
ABSTRACT This study proposes to incorporate an antifungal agent (potassium sorbate, KS) to post-c... more ABSTRACT This study proposes to incorporate an antifungal agent (potassium sorbate, KS) to post-consumer recycled polyethylene terephthalate (PCRPET), by adding KS to the dip solution through which PCRPET normally passes after extrusion, in order to acquire a non-stick silicone coating, which prevents individual packages from adhering to each other while stacked. This method of imparting antifungal activity to the packaging is far more advantageous than adding KS to the extruder feed because it results in virtually no alterations to the colour and mechanical properties of PCRPET, which is a major issue when KS is added to the extruder feed. The antifungal efficacy of the active packaging was demonstrated against Botrytis cinerea growth by a novel method which mimics the action of the antifungal agent under fruit contact conditions. A reduction by 2 log cycles was observed when the initial concentration of the mould was 105 conidia/mL. The active packaging was effective over a test period lasting 6 months. The packaging microstructure was visualized by scanning electron microscopy (SEM); its thermal properties were characterized using a differential scanning calorimeter (DSC); its optical properties were characterized using CIE Lab colorimetry; and its mechanical properties were characterized by measuring resistance to dynamic compression. The mechanical properties showed no significant difference (P > 0.05) with those of the control (PCRPET without KS), and despite a statistically significant difference (P < 0.05) in the colour parameters (L*, a* and b*), the total colour difference (ΔE*) was found to be too small to be visually noticed. This study achieved the aim of adding antifungal activity to PCRPET packaging with little or no perceptible changes to its mechanical, thermal and optical properties and virtually no changes being made to the standard high-speed packaging production line.
The Chemical Engineering Journal, 1984
ABSTRACT Packed bubble columns offer several advantages over bubble columns. For example, the gas... more ABSTRACT Packed bubble columns offer several advantages over bubble columns. For example, the gas holdup and mass transfer characteristics of packed bubble columns are superior to those of bubble columns, and the axial dispersion coefficient values are much lower.The gas holdup and mixing characteristics of a number of packings are considered in this article. An empirical equation is proposed to estimate the gas holdup values. The effects of the packing size, the column diameter, the liquid viscosity and the ionic strength on the gas holdup are discussed. The axial dispersion coefficient values for packings with nominal sizes of 0.025 m and above are correlated by means of a model based on the bulk liquid circulation in the column.
Journal of Food Science, 2015
Air frying is being projected as an alternative to deep fat frying for producing snacks such as F... more Air frying is being projected as an alternative to deep fat frying for producing snacks such as French fries. In air frying, the raw potato sections are essentially heated in hot air containing fine oil droplets, which dehydrates the potato and attempts to impart the characteristics of traditionally produced French fries, but with a substantially lower level of fat absorbed in the product. The aim of this research is to compare: (1) the process dynamics of air frying with conventional deep fat frying under otherwise similar operating conditions, and (2) the products formed by the 2 processes in terms of color, texture, microstructure, calorimetric properties, and sensory characteristics. Although, air frying produced products with a substantially lower fat content but with similar moisture contents and color characteristics, it required much longer processing times, typically 21 min in relation to 9 min in the case of deep fat frying. The slower evolution of temperature also resulted in lower rates of moisture loss and color development reactions. Differential scanning calorimetry (DSC) studies revealed that the extent of starch gelatinization was also lower in the case of air fried product. In addition, the 2 types of frying also resulted in products having significantly different texture and sensory characteristics.
Journal of Food Science, 2014
Fried products impose a health concerns due to considerable amount of oil they contain. Productio... more Fried products impose a health concerns due to considerable amount of oil they contain. Production of snack foods with minimal oil content and good management of oil during frying to minimize the production of toxic compounds continue to be challenging aims. This paper aims to investigate the possibility of producing a fat-free food snack by replacing frying oil with a nonfat medium. Glucose was melted and its temperature was then brought to 185 °C and used to fry potato strips, to obtain a product referred here as glucose fries. The resulting product was compared with French fries prepared conventionally under conditions that resulted in similar final moisture content. The resulting products were also examined for crust formation, texture parameters, color development and glucose content. Stereo microscope images showed that similar crusts were formed in the glucose fries and French fries. Texture parameters were found to be similar for both products at 5 and 2 mm penetration depth. The maximum hardness at 2 mm penetration depth was also similar for both products, but different from cooked potato. The color development that characterized French fries was also observed in glucose fries. The glucose content in glucose fries was found to be twice the content of French fries, which is to be expected because glucose absorbed or adhered to the surface. In conclusion, glucose fries, with similar texture and color characteristics to that of French fries, can be prepared by using a nonfat frying medium.
Trends in Food Science & Technology, 2015
ABSTRACT Regulatory, safety, and environmental issues have prompted the development of aqueous en... more ABSTRACT Regulatory, safety, and environmental issues have prompted the development of aqueous enzymatic extraction (AEE) for extracting components from oil-bearing materials. The emulsion resulting from AEE requires de-emulsification to separate the oil; when enzymes are used for this purpose, the method is known as aqueous enzymatic emulsion de-emulsification (AEED). In general, enzyme assisted oil extraction is known to yield oil having highly favourable characteristics. This review covers technological aspects of enzyme assisted oil extraction, and explores the quality characteristics of the oils obtained, focusing particularly on recent efforts undertaken to improve process economics by recovering and reusing enzymes.
Food Mixing, 2009
... Massey et al. 2001; Lau & Dickinson 2005; Jakubczyk & Niranjan 2006), where the dispe... more ... Massey et al. 2001; Lau & Dickinson 2005; Jakubczyk & Niranjan 2006), where the dispersion is stable and air release during the measurement process is negligible. In the ... Massey et al. 2001; Lau & Dickinson 2005). This trend ...
Food Materials Science, 2008
... Massey et al. 2001; Lau and Dickinson 2005; Jakubczyk and Niranjan 2006), where the dispersio... more ... Massey et al. 2001; Lau and Dickinson 2005; Jakubczyk and Niranjan 2006), where the dispersion is stable and air release during the measurement process is negligible. In the ... Massey et al. 2001; Lau and Dickinson 2005). This trend ...
Trends in Food Science & Technology, 2002
... advantages, is gaining popularity as a complimentary processing step in the chain of integrat... more ... advantages, is gaining popularity as a complimentary processing step in the chain of integratedfood processing. ... Various methods to increase the rate of mass transfer, such as application of high hydrostatic pressure, high electrical field pulses, ultrasound, vacuum and ...