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Effect of blanching and drying air temperature on quality of dried amla flakes

Effect of blanching and drying air temperature on quality of dried amla flakes

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Experiments were conducted to assess the effect of blanching and drying air temperature on
the quality attributes of dried amla flakes. The raw amla fruits were subjected to three
different treatments i.e., untreated UT, steam blanching SB and hot water blanching prior to
convective tray drying at temperature of 50°C, 60°C and 70°C and refractive window drying
at temperature of 60°C, 70°C and 80°C. In addition to the evaluation of drying rate of
different combinations of amla pulp in both methods of drying, the dried amla flakes (nearly
7% db) were analyzed for different quality attributes such as moisture content, water activity,
ash content, bulk density, ascorbic acid, antioxidants, total phenolic content, color and overall
acceptability. The data indicated that different quality parameters of dried amla flakes were
significantly affected by blanching and drying type. In addition to increasing the moisture
content, water activity and ash percentage of amla pulp, blanching treatment increased the
drying rates for amla samples. The untreated samples generally had lower drying rates than
those of the treated samples. The flakes blanched had a bright visual appearance as compared
to UT amla flakes. Refractive window drying resulted in minimal loss of overall quality of
amla flakes when compared with convective tray drying. Steam blanched amla flakes
refractive window dried witnessed highest retention of ascorbic acid content, antioxidant
activity and total phenolic content with lower levels of moisture content, water activity and
ash content. Maximum yield recovery (14.13%) was found in steam blanched amla flakes
refractive dried at 60C.

Experiments were conducted to assess the effect of blanching and drying air temperature on
the quality attributes of dried amla flakes. The raw amla fruits were subjected to three
different treatments i.e., untreated UT, steam blanching SB and hot water blanching prior to
convective tray drying at temperature of 50°C, 60°C and 70°C and refractive window drying
at temperature of 60°C, 70°C and 80°C. In addition to the evaluation of drying rate of
different combinations of amla pulp in both methods of drying, the dried amla flakes (nearly
7% db) were analyzed for different quality attributes such as moisture content, water activity,
ash content, bulk density, ascorbic acid, antioxidants, total phenolic content, color and overall
acceptability. The data indicated that different quality parameters of dried amla flakes were
significantly affected by blanching and drying type. In addition to increasing the moisture
content, water activity and ash percentage of amla pulp, blanching treatment increased the
drying rates for amla samples. The untreated samples generally had lower drying rates than
those of the treated samples. The flakes blanched had a bright visual appearance as compared
to UT amla flakes. Refractive window drying resulted in minimal loss of overall quality of
amla flakes when compared with convective tray drying. Steam blanched amla flakes
refractive window dried witnessed highest retention of ascorbic acid content, antioxidant
activity and total phenolic content with lower levels of moisture content, water activity and
ash content. Maximum yield recovery (14.13%) was found in steam blanched amla flakes
refractive dried at 60C.

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Effect of blanching and drying air temperature on quality of dried amla flakes

  1. 1. PRESENTED BY: ARSHPREET KAUR L-2K17-AE-10-BIV B.TECH. (AGRI. ENGG. AND TECH.) MAJOR ADVISIOR: Dr. PREETINDER KAUR (SENIOR RESEARCH ENGINEER) DEPTT. PROCESSING & FOOD ENGG.
  2. 2. CONTENT • Introduction • Review of literature • Material and Methods • Results and Discussion • Summary and Conclusion • References
  3. 3. SCIENTIFIC NAME- EMBLICA OFFICINALIS AVERAGE WEIGHT- 30-60g Possesses medicinal and therapeutic values Consumed in the form of candy, trifala, jam, pickle Rich in antioxidant and polyphenols VIT-C CONTENT- 600-700 mg INTRODUCTION
  4. 4. • INDIA PRODUCTION: 111.1 million tons AREA: 49.62 million hectares (Indian Horticultural database 2016) • Recommended Varities in PAU Balwant Neelum Kanchan PROBLEMS • Post harvest losses during peak harvesting periods • Highly perishable nature makes amla prone to damage • Improper handling at various stages
  5. 5. • Improve the quality of the dried fruits. • Prevents enzymatic spoilage. • Common way to preserve agricultural produce. • Increase shelf-life • Promote food security. • Also reduce post harvest waste • Reduce transportation cost SOLUTIONS
  6. 6. Steam Blanching Hot Water Blanching BLANCHING METHOD USED FOR AMLA PUREE
  7. 7. • It involves scalding vegetables in boiling water or steam for a short time • It stops enzyme actions which can cause loss of flavor, color and texture. • Products are immersed in hot water (70 to 100°C) for several minutes. • Then blanched samples are drained and cooled before being sent to the next processing operation. • Increases leaching losses
  8. 8. Convective Tray drying Refractive Window drying DRYING METHOD USED FOR AMLA PUREE
  9. 9. CONVECTIVE TRAY DRYING SYSTEM • Traditional drying method • Used for drying of the solids like pasty materials and lumpy solids of wet powder • Requires longer time and high energy
  10. 10.  The general design of tray dryer includes a cabinet containing removable trays on which wet solid material is placed in plates and hot air is blown from across and bottom of the tray in cross-circulation manner to evaporate moisture from solids.  To operate the drier on electric energy, electric heater consisting of heating rods attached to the drying chamber.  After reaching desired drying state, the product is removed.  The general batch drying cycle in convective Tray dryer is of 4-48 hrs.  This dryer is useful when the production rate is small and in batch and have lower moisture to be removed.
  11. 11. REFRACTION BASED DRYING SYSTEM • Novel drying method • Used for drying heat sensitive products • Used for drying juices and purees • Maintains flavour, colour and nutrients
  12. 12.  The loss of thermal energy from water to the environment occurs through conduction, convection and radiation.  If the metalized polyester film is placed on the surface of the water, the loss of energy can only occur by conduction.  When a wet raw material is spread on the surface of the metalized polyester film, the water in the material creates a "window" that allows infrared energy to pass through the material.  The heat behaves as if there were no membranes present and is transferred directly to the material to be dried.  This window closes slowly when moisture loss and heat transfer of the product decrease and the infrared energy window is closed. HOT WATER BATH CONVECTIO N CONDUCTION RADIATION WET MATERIAL METALIZED POLYESTER FILM
  13. 13. 1. To compare the effect of three different types of treatments i.e. no blanching, steam blanching and hot water blanching on amla flakes. OBJECTIVE 2. To conduct comparison analysis of convective and refractive window based drying of amla puree
  14. 14. REVIEW OF LITERATURE
  15. 15. Reference Title Observations Geetha et al (2006) Effect of blanching on physicochemical characteristics of amla. Evaluated the effect of blanching done prior to processing of amla fruit and concluded that blanching has marked effect on retention of nutrients and various fruit quality parameters . Alam et al (2019) Influence of shape, pre- treatment and drying air temperature on quality of dried amla In order to inactivate the peroxidase enzyme in amla, various pre-treatments were given before mechanical treatment with highest Vit-C retention of 83% in steam blanching Alam et al (2002) Studies on drying of amla (Phyllanthus Emblica) Chakaiya and Banarsi varities of amla were dried in mechanical tray dryer at 60℃ after pre- treatment and compared with sun dried samples.
  16. 16. Reference Title Observations Clarke (2004) Refractance window- “down under” Reviewed new novel dehydration technology i.e. refractance window which offers both relatively low cost operation with excellent retention of colour, flavour and nutrients. Zalpouri et al (2020) Influence of developed refractance based drying method on physical parameter of potato flakes. Developed and evaluated refractive window dryer for dehydration of potato. It was observed that the physical properties of potato flakes were significantly affected by TSS, blanching time, and drying temperature
  17. 17. MATERIAL AND METHODS
  18. 18. DESIGN OF EXPERIMENT Item Description Crop Variety Neelum Pretreatment Washing, Peeling Blanching methods 1. Hot water blanching for 10 minutes(90-100°C) 2. Steam Blanching (90-100° C) Drying methods 1. Refractive Based Drying 2. Convective Tray Drying Quality Physical Parameters Chemical Parameters Moisture Content, Water Activity, Ash Content, Color, Bulk density Total Phenol Content, Antioxidant Capacity, Ascorbic Acid Content
  19. 19. S.No. Equipment Description Make/ Model/ Manufacturers Test performed/ Quality measured 1 Universal weighing balance 5kg capacity with least count of 0.05g. Excell ZERO NET DC balance Weighing (g) 2 Hot air oven Range 0-2500C Model SNW-143, Kilburn oven Macneil & Magor Ltd, India Moisture content 3 Colorimeter Color Reader CR-10 Make: Miniscan XE plus hunter lab colorimeter Colour (L, a, b) LIST OF EQUIPMENTS
  20. 20. 4 Electronic UV – vis spectrophoto meter Digital spectronic Model: Rayleigh, UV-2601 Protein (mg/g), Reducing sugar (mg/g), Total sugar (mg/g), Starch content (mg/g) 5 Refractromete r Having range 0- 32°Brix Make: Erma TSS (°B) 6 Refraction based drying system Novel contact dryer Fabricated in Pilot plant, Department Processing and Food Engineering, PAU Drying 7 Convective tray dryer Maximum attainable temperature of 200ºC Model- 012E, Type Elect, Manufactured by Macneil and Magor Ltd Mechanical drying
  21. 21. PROCESS FLOW CHART FOR PROCESSING OF AMLA FLAKES
  22. 22. PREPARATION OF AMLA PUREE  Pre-cooled fruits were sorted to obtain uniform sized fruits free from any injury, diseases or bruising and washed thoroughly with running tap water to remove any foreign material adhering to them. Three different treatments were used on raw amla. One of the sets of amla of about 5Kg was left unblanched (UB) and the other two sets of raw amla of 5Kg each were blanched. For the inactivation of enzymatic browning, the samples were blanched by two different methods i.e.,  (i) Steam Blanching (SB): Raw amla’s were steamed over boiling water in a water bath at 100-110℃ for 20 minutes and cooled immediately in ice cold water before pulping  (ii) Hot water blanching (HWB): Raw amla’s were submerged in boiling water for 10 minutes at 98-100℃ and cooled immediately in ice cold water before pulping
  23. 23. DESIGN OF EXPERIMENT FOR DRYING OF AMLA PUREE Treatment Temperature (℃) Unblanched (100g) 50 60 70 Hot Water Blanched(100g) 50 60 70 Steam Blanched(100g) 50 60 70 Treatment Temperature (℃) Unblanched (500g) 60 70 80 Hot Water Blanched(500g) 60 70 80 Steam Blanched(500g) 60 70 80
  24. 24. Convective tray dried amla flakes UB SB HWB
  25. 25. REFRACTION BASED DRYING SYSTEM AT 0 min After 15 min After 30 min FINAL PRODUCT UB SB HWB
  26. 26. Experiment Name of the experiment To study the effect of blanching and air drying temperature on quality of amla Location Department of Processing and Food Engineering, College of Agricultural Engineering and Technology, PAU, Ludhiana Methodology The blanched and dried product will be evaluated on the basis of  Products parameters: A) Physico-chemical parameters B) Bio-active compound characteristics
  27. 27. MOISTURE CONTENT (MC) The moisture content of fresh and dried amla was determined by standard oven method (Anon 1975). Moisture content (%wb) = 𝑾𝟏−𝑾𝟐 𝑾𝟏 x 100 Moisture content (%db) = 𝑾𝟏− 𝑾𝟐 𝑾𝟐 x 100 Where, W1 = initial weight of the sample (g) W2 = final weight of the sample (g)
  28. 28.  Bulk density of the dried amla powder was determined using a container or cylinder of known volume and electronic balance. Bulk density = 𝑴 𝑽 Where, M = mass of the sample in grams V = volume of the same sample in cc BULK DENSITY ASH CONTENT  Bulk density of the dried amla powder was determined using a muffle furnace and the sample was ignited at 550℃ for 4-6 hrs. Ash Content = 𝑾𝒆𝒊𝒈𝒉𝒕 𝒐𝒇 𝒓𝒆𝒔𝒊𝒅𝒖𝒆 𝑾𝒆𝒊𝒈𝒉𝒕 𝒐𝒇 𝒔𝒂𝒎𝒑𝒍𝒆 X 100 Where, M = mass of the sample in grams V = volume of the same sample in cc
  29. 29. WATER ACTIVITY • Mc Donald et al (1956) method was followed to determine the total phenolic content in amla sample TOTAL PHENOLIC CONTENT (TPC) • The water activity determined by using water activity meter (Hygrolabrotronic, Mumbai, India)
  30. 30. DETERMINATION OF ASCORBIC ACID • Ranganna et al method (1986) was followed to determine the ascorbic acid content in amla samples. • Antioxidant Capacity was measured by the method of De et al (2002) DETERMINATION OF ANTIOXIDANT CAPACITY
  31. 31. Color:- Colour was determined using Hunter Lab Miniscan XE Plus Colorimeter. Colour change, (∆E) = √ (ΔL2 + Δa2 + Δb2) Chroma, (𝐶) = 𝑎2 + 𝑏2 Hue angle, (α) = tan-1( 𝑏 𝑎 ) Where, ΔL, Δa and Δb are deviations from L, a, and b values of fresh sample.
  32. 32. RESULT AND DISCUSSION
  33. 33. ASH CONTENT 8-9% WATER ACTIVITY (0.55-0.56) MOISTURE CONTENT (83-85%) ASCORBIC ACID CONTENT (2154- 2200mg/100g) ANTIOXIDANT CAPACITY (657-664 %) TOTAL PHENOLIC CONTENT (270-300 mg GAE/100g) PHYSICO-CHEMICAL COMPOSITION OF RAW AMLA BULK DENSITY (0.84-0.85 g/ml)
  34. 34. PHYSICO-CHEMICAL COMPOSITION OF AMLA PUREE S. No. Parameter Pulp Unblanched Steam Blanched Hot-Water Blanched 1 Moisture Content(%wb) 83.87±1.553 85.83±2.984 87.02±0.685 2 Ash Content (%) 8.04±0.05 8.86±0.032 9.62±0.036 3 Water Activity 0.55±0.002 0.55±0.001 0.24±0.006 4 Bulk Density(g/ml) 0.84±0.0007 0.84±0.008 0.84±0.001 5 L value 66.9±1.2 71.11±2.77 73.1±1.07 6 Color Change(∆E) 2.49±0.560 6.07±1.886 7.66±0.953 7 Chromaticity 16.51±0.445 21.92±0.582 21.71±0.817 8 Hue angle (a) 27.9±0.918 -88.05±0.523 -85.35±0.588 7 Ascorbic Acid(mg/100gm) 2154.3±42.846 1960.2±35.79 1798.3±39.058 8 Antioxidant Activity (%) 657.96±5.945 712.14±5.944 734.50±9.984 9 Total Phenolic Content, (mg GAE/100gm) 270.26±27.536 289.55±31.344 276.49±34.207
  35. 35. OPTIMIZATION OF DRYING PROCESS
  36. 36. 0 100 200 300 400 500 600 0.00 15.00 30.00 45.00 60.00 75.00 90.00 105.00 120.00 Moisture Content 9%db) Time (mins) 70°C UB SB HWB Variation in moisture content at 70℃ 0 100 200 300 400 500 600 0 60 120 180 240 300 360 420 Moisture Content (%db)) Time (mins) 70°C UB SB HWB CONVECTIVE TRAY DRIER REFRACTIVE WINDOW DRIER
  37. 37. Variation in drying rate at 70℃ CONVECTIVE TRAY DRIER REFRACTIVE WINDOW DRIER 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0 60 120 180 240 300 360 420 Drying Rate (gm/min) Time (mins) 70°C UB SB HWB 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 15 30 45 60 75 90 105 120 Drying Rate (gm/min) Time (mins) 70℃ UB SB HWB
  38. 38. Recovery % of dried product Parameter Recovery % Convective Tray Drying Treatment Unblanched 50°C 12.8 60°C 12.15 70°C 11.64 Steam-Blanched 50°C 12.21 60°C 12.08 70°C 11.55 Hot Water Blanched 50°C 11.37 60°C 11.24 70°C 10.71 Refractance Window Drying Treatment Unblanched 60°C 13.4 70°C 12.6 80°C 11.2 Steam-Blanched 60°C 14.13 70°C 13.6 80°C 12.16 Hot Water Blanched 60°C 13.12 70°C 12.4
  39. 39. Effect of blanching and drying temperature on Color (Hue Angle) of amla Convective Tray Drier Refractive Window Drier -200 -150 -100 -50 0 50 100 150 50 60 70 Hue Angle (°) Temperature (°C) UB SB HWB -150 -100 -50 0 50 100 60 70 80 Hue Angle (°) Temperature (°C) UB SB HWB
  40. 40. Effect of blanching and drying temperature on Total Phenolic Content of amla Convective Tray Drier Refractive Window Drier 0 10 20 30 40 50 60 70 80 50 60 70 Total Phenolic Content (mg GAE/100gm) Temperature (°C) UB SB HWB 0 10 20 30 40 50 60 70 80 60 70 80 Total Phenol Content (mg GAE/100gm) Temperature (°C) UB SB HWB
  41. 41. Effect of blanching and drying temperature on antioxidant activity of amla 0 10 20 30 40 50 60 70 80 90 50 60 70 Antioxidant Capacity(%) Temperature (°C) UB SB HWB 0 10 20 30 40 50 60 70 80 90 60 70 80 Antioxidant Capacity (%) Temperature (°C) UB SB HWB Convective Tray Drier Refractive Window Drier
  42. 42. Effect of blanching and drying temperature on Ascorbic Acid Content of amla Convective Tray Drier Refractive Window Drier 0 50 100 150 200 250 300 350 400 50 60 70 Ascorbic Acid (mg/100gm) Temperature (°C) UB SB HWB 0 50 100 150 200 250 300 350 400 60 70 80 Ascorbic Acid (mg/100gm) Temperature (°C) UB SB HWB
  43. 43. SUMMARY AND CONCLUSION
  44. 44.  Blanching had significant effect on physico-chemical composition of raw amla. Blanching increased the moisture content, water activity and the ash percentage. Bulk Density was to found to be nearly same in all the three treatments. Blanched samples had higher L value when compared with unblanched sample.  Blanching had a positive impact on protecting the antioxidant activity of raw amla. However, ascorbic acid content and total phenolic content reduced after hot water and steam blanching.  The blanching pre-treatment increased the drying rates for amla samples. The untreated samples generally had lower drying rates than those of the pre- treated samples.  Moisture content of Refractive window dried samples was lower than convective tray dried samples.  The flakes blanched had a bright visual appearance. However, the unblanched flakes appeared to have more darkness after drying. Therefore, they lost their natural brightness and showed redness when dried. This change was manifested by an increase in a-value and a decrease of the b-value.  Refractive window drying system allowed higher retention of bioactive compounds when compared to convective tray drying  In conclusion, steam blanched sample refractive window dried at 70℃ showed best retention in terms of physical parameters and bio active compounds.
  45. 45. REFERENCES
  46. 46. Alam M S, Sharma S R, and Nidhi (2002) Studies on drying of amla (Phyllanthus Emblica). In paper presented in XXXVI annual convention of ISAE, IIT Kharagpur, January 28-30. Alam M S, Singh A and Chawan P (2019) Influence of shape, pre-treatment and drying air temperature on quality of dried amla. Int Com. Agri Bio Engg 22(1). Clarke P T (2004) Refractance window- “down under”. Proc of the 14th Int Drying Symp pp 813-20. São Paulo, Brazil São Paulo, Brazil. Geetha N S, Kumar S, Rana G S (2006) Effect of blanching on physicochemical characteristics of amla. Haryana J.Horti.Sci 35(1&2): 67-68. Zalpouri R, Kaur P, Kaur A (2020) Influence of developed refractance based drying method on physical parameter of amla flakes. Int J Chem Stud 8(3): 2833-2838.

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