Nishant R Swami Hulle | Tezpur University (original) (raw)

Research Papers by Nishant R Swami Hulle

Journal of Food Process Engineering, 2014

ABSTRACT Flow characteristics of aloe vera juice concentrates (1.5–5.5°Brix) were determined over... more ABSTRACT Flow characteristics of aloe vera juice concentrates (1.5–5.5°Brix) were determined over a range of temperatures (15–55C) by using coaxial cylinder geometry. Aloe vera juice exhibited non-Newtonian fluid behavior which was well described by power law model. Functional groups were characterized by Fourier-transform infrared (FTIR) spectroscopy indicating the presence of O-acetyl and shifting of –CH bonds. Effect of test temperatures at different shear rates on viscosity was evaluated using Arrhenius-type equation and the activation energy values were evaluated which ranged between 12.148 and 53.073 kJ/mol. Effect of concentration was evaluated using power type and exponential type equations. An expression for combined effect of temperature and concentration was developed. Small amplitude oscillation sweep measurement was also carried out and the frequency sweep test exhibited viscoelastic nature of juice.Practical ApplicationsAloe vera is commercially very important crop and is being used in food, medicines and cosmetics. Rheological properties are important parameters and are used to assess the functional and structural properties of food products. In this study, the flow and deformation characteristics of aloe vera juice concentrates were evaluated as a function of temperature and concentration. An expression for the combined effect of concentration and temperature on the viscosity was evaluated. Oscillatory sweep experiments can be used to assess the viscoelastic properties, which are useful to develop the products of desired functionalities. The changes in functional groups due to concentration can be assessed using FTIR spectroscopy analysis.

Journal of Food Processing and Preservation

The effect of high pressure processing (HPP) (600 MPa/15 min/56 °C) and thermal processing (TP) (... more The effect of high pressure processing (HPP)
(600 MPa/15 min/56 °C) and thermal processing (TP)
(95 °C/5 min) on the quality characteristics of aloe
vera-litchi mixed beverage samples (ALMB) stored at
4, 15 and 25 °C were studied. The total color difference and
browning index of ALMB samples increased with the storage
period for both HPP and TP treated samples under all storage
conditions. HPP of ALMB resulted in inactivation of
pectinmethylesterase (PME), polyphenoloxidase (PPO) and
peroxidase (POD) to 34, 65 and 62 %, respectively after immediate processing, whereas, TP treatment lead to 83, 79 and
78 %, respectively. The residual activity of all the studied
enzymes decreased with storage period. The ascorbic acid loss
of up to 22 % was observed after HPP treatment and up to
31 % for thermally treated samples. Minimal changes were
noted for phenolics content after HPP as well as thermal processing. The natural microbiota present in samples was below
the detection limit (1 log CFU/mL) throughout the storage
period. The shelf life of HPP and TP treated samples stored
at 4 °C was estimated to be 100 and 80 days, respectively,
based on the sensory quality, ascorbic acid degradation and
instrumental color difference.

Flow characteristics of aloe vera juice concentrates (1.5–5.5°Brix) were determined over a range ... more Flow characteristics of aloe vera juice concentrates (1.5–5.5°Brix) were determined
over a range of temperatures (15–55C) by using coaxial cylinder geometry. Aloe
vera juice exhibited non-Newtonian fluid behavior which was well described by
power law model. Functional groups were characterized by Fourier-transform
infrared (FTIR) spectroscopy indicating the presence of O-acetyl and shifting of
–CH bonds. Effect of test temperatures at different shear rates on viscosity was
evaluated using Arrhenius-type equation and the activation energy values were
evaluated which ranged between 12.148 and 53.073 kJ/mol. Effect of concentration was evaluated using power type and exponential type equations. An expression for combined effect of temperature and concentration was developed. Small
amplitude oscillation sweep measurement was also carried out and the frequency
sweep test exhibited viscoelastic nature of juice.

Effect of pressure level (60–740 MPa), process dwell time (3–40 min), and pH (2.32–5.68) on rheol... more Effect of pressure level (60–740 MPa), process dwell time (3–40 min), and pH (2.32–5.68) on rheological
properties, pectinmethylesterase (PME) enzyme activity and microbiological characteristics of aloe vera
juice was studied. A quadratic model was developed for rheological parameters and it was found that
pressure level had the most significant effect on all the responses (p < 0.05) followed by pH and
dwell time. Pectinmethylesterase activity was evaluated and a maximum of up to 30% inactivation was
obtained. Microbial analysis of high pressure treated samples revealed that samples treated at 400 MPa
for 20 min at pH 4 reduced microbial counts to <10 cfu mL−1 achieving up to 5.66 log cycle reduction.

The effect of high-pressure (HP) pretreatments (300–500 MPa for 5–15 min) on dehydration characte... more The effect of high-pressure (HP) pretreatments (300–500 MPa for 5–15 min) on dehydration
characteristics of aloe vera cubes (AVC), dried at 50–70°C and air velocity of 1–2 m/s, was studied.
Pretreatments resulted in higher drying rates, leading to a reduction in drying time compared to
untreated ones. The drying rate and drying time were most significantly affected (p < 0.05) by the
drying temperature, followed by air velocity, pressure level, and dwell time. HPP enhanced the
firmness of AVC with a maximum of up to 21% for the sample treated at 500 MPa for 15 min.
Microstructural analysis using scanning electron microscopy (SEM) indicated non-uniform
structures in the pretreated and dried AVC samples. Semi-quantitative elemental detection (EDS)
confirmed the presence of a considerable amount (14%) of calcium in aloe vera.

Journal of Food Process Engineering, 2014

ABSTRACT Flow characteristics of aloe vera juice concentrates (1.5–5.5°Brix) were determined over... more ABSTRACT Flow characteristics of aloe vera juice concentrates (1.5–5.5°Brix) were determined over a range of temperatures (15–55C) by using coaxial cylinder geometry. Aloe vera juice exhibited non-Newtonian fluid behavior which was well described by power law model. Functional groups were characterized by Fourier-transform infrared (FTIR) spectroscopy indicating the presence of O-acetyl and shifting of –CH bonds. Effect of test temperatures at different shear rates on viscosity was evaluated using Arrhenius-type equation and the activation energy values were evaluated which ranged between 12.148 and 53.073 kJ/mol. Effect of concentration was evaluated using power type and exponential type equations. An expression for combined effect of temperature and concentration was developed. Small amplitude oscillation sweep measurement was also carried out and the frequency sweep test exhibited viscoelastic nature of juice.Practical ApplicationsAloe vera is commercially very important crop and is being used in food, medicines and cosmetics. Rheological properties are important parameters and are used to assess the functional and structural properties of food products. In this study, the flow and deformation characteristics of aloe vera juice concentrates were evaluated as a function of temperature and concentration. An expression for the combined effect of concentration and temperature on the viscosity was evaluated. Oscillatory sweep experiments can be used to assess the viscoelastic properties, which are useful to develop the products of desired functionalities. The changes in functional groups due to concentration can be assessed using FTIR spectroscopy analysis.

Journal of Food Processing and Preservation

The effect of high pressure processing (HPP) (600 MPa/15 min/56 °C) and thermal processing (TP) (... more The effect of high pressure processing (HPP)
(600 MPa/15 min/56 °C) and thermal processing (TP)
(95 °C/5 min) on the quality characteristics of aloe
vera-litchi mixed beverage samples (ALMB) stored at
4, 15 and 25 °C were studied. The total color difference and
browning index of ALMB samples increased with the storage
period for both HPP and TP treated samples under all storage
conditions. HPP of ALMB resulted in inactivation of
pectinmethylesterase (PME), polyphenoloxidase (PPO) and
peroxidase (POD) to 34, 65 and 62 %, respectively after immediate processing, whereas, TP treatment lead to 83, 79 and
78 %, respectively. The residual activity of all the studied
enzymes decreased with storage period. The ascorbic acid loss
of up to 22 % was observed after HPP treatment and up to
31 % for thermally treated samples. Minimal changes were
noted for phenolics content after HPP as well as thermal processing. The natural microbiota present in samples was below
the detection limit (1 log CFU/mL) throughout the storage
period. The shelf life of HPP and TP treated samples stored
at 4 °C was estimated to be 100 and 80 days, respectively,
based on the sensory quality, ascorbic acid degradation and
instrumental color difference.

Flow characteristics of aloe vera juice concentrates (1.5–5.5°Brix) were determined over a range ... more Flow characteristics of aloe vera juice concentrates (1.5–5.5°Brix) were determined
over a range of temperatures (15–55C) by using coaxial cylinder geometry. Aloe
vera juice exhibited non-Newtonian fluid behavior which was well described by
power law model. Functional groups were characterized by Fourier-transform
infrared (FTIR) spectroscopy indicating the presence of O-acetyl and shifting of
–CH bonds. Effect of test temperatures at different shear rates on viscosity was
evaluated using Arrhenius-type equation and the activation energy values were
evaluated which ranged between 12.148 and 53.073 kJ/mol. Effect of concentration was evaluated using power type and exponential type equations. An expression for combined effect of temperature and concentration was developed. Small
amplitude oscillation sweep measurement was also carried out and the frequency
sweep test exhibited viscoelastic nature of juice.

Effect of pressure level (60–740 MPa), process dwell time (3–40 min), and pH (2.32–5.68) on rheol... more Effect of pressure level (60–740 MPa), process dwell time (3–40 min), and pH (2.32–5.68) on rheological
properties, pectinmethylesterase (PME) enzyme activity and microbiological characteristics of aloe vera
juice was studied. A quadratic model was developed for rheological parameters and it was found that
pressure level had the most significant effect on all the responses (p < 0.05) followed by pH and
dwell time. Pectinmethylesterase activity was evaluated and a maximum of up to 30% inactivation was
obtained. Microbial analysis of high pressure treated samples revealed that samples treated at 400 MPa
for 20 min at pH 4 reduced microbial counts to <10 cfu mL−1 achieving up to 5.66 log cycle reduction.

The effect of high-pressure (HP) pretreatments (300–500 MPa for 5–15 min) on dehydration characte... more The effect of high-pressure (HP) pretreatments (300–500 MPa for 5–15 min) on dehydration
characteristics of aloe vera cubes (AVC), dried at 50–70°C and air velocity of 1–2 m/s, was studied.
Pretreatments resulted in higher drying rates, leading to a reduction in drying time compared to
untreated ones. The drying rate and drying time were most significantly affected (p < 0.05) by the
drying temperature, followed by air velocity, pressure level, and dwell time. HPP enhanced the
firmness of AVC with a maximum of up to 21% for the sample treated at 500 MPa for 15 min.
Microstructural analysis using scanning electron microscopy (SEM) indicated non-uniform
structures in the pretreated and dried AVC samples. Semi-quantitative elemental detection (EDS)
confirmed the presence of a considerable amount (14%) of calcium in aloe vera.