I= EFFECT OF SELECTED SWEETENERS (CALORIC AND NON CALORIC) CHEMICAL PRESERVATIVES AND ANTIOXIDANTS ON THE PHYSIOCHEMICAL AND MICROBIAL ANALYSIS OF DEHYDRATED FRUITS
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Title of Thesis
EFFECT OF SELECTED SWEETENERS (CALORIC AND NON CALORIC) CHEMICAL PRESERVATIVES AND ANTIOXIDANTS ON THE PHYSIOCHEMICAL AND MICROBIAL ANALYSIS OF DEHYDRATED FRUITS

Author(s)
Muhammad Ayub
Institute/University/Department Details
NWFP Agricultural University, Peshawar
Session
2004
Subject
Food Science
Number of Pages
450
Keywords (Extracted from title, table of contents and abstract of thesis)
sweeteners, caloric sweeteners, non caloric sweeteners, chemical preservatives, antioxidants, dehydrated fruits, nutritive sweeteners, sucrose, glucose, fructose, non nutritive sweeteners, saccharine, cyclamate, aspartame, potassium sorbate, potassium metabisulphite, dehydrated intermediate moisture, guava, apple, carrot

Abstract
In first part of this research a study was carried out to investigate the effect of individual and combined dose of nutritive sweeteners (NS) of sucrose, glucose and fructose and non nutritive sweeteners (NNS) of saccharine, cyclamate and aspartame in the presence of antioxidants [citric acid (CA) and ascorbic acid (AA)] and chemical preservatives of potassium sorbate (PS) and potassium metabisulphite (PMS)) on the overall quality of dehydrated intermediate moisture (1M) guava, apple and carrot slices. NS were used in different concentrations (20, 30, 40 and 50° brix (bx), while NNS sweeteners were used with equal to the concentration of sucrose sweetness (0.5-5g). Product was put in solutions for twenty four hours, dehydrated and stored at ambient temperature (20- 30°C). Analysis were carried out for water activity (aw), AA, total soluble solids (TSS), acidity, sugar-acid ratio, total microbial count and for organoleptic evaluation fortnightly for a total period of ninety days. In NS the aw (0.95, fresh) significantly (p<0.05) decreased after dehydration (0.63). The aw of NNS dehydrated guava product was in the range 0.9619-0.9041. The TSS of fresh guava slices (10° bx) increased (38.24° bx) with NS after osmotic dehydration and decreased (4.63° bx) with NNS. AA content of guava slices (293.9 mg/l00g) significantly (p<0.05) decreased (44.51 mg/l00g) with NS and with NNS (35.6 mg/l00g) after dehydration. Maximum decrease in AA was observed in sample T2 (glucose) and minimum in sample T4 (sucrose, CA and PMS), while with NNS maximum decrease was observed in sample N10 (aspartame) and minimum in sample N 12 (aspartame, AA and PMS). Percent acidity of NS and NNS guava slices significantly (p<0.05) increased, while pH decreased after dehydration.

In second part of this study the influence of NS and NNS antioxidants and chemical preservatives (as used for guava slices) was studied on the preservation of dehydrated 1M apple slices. The aw of apple slices (0.951, fresh) significantly (p<0.05) decreased with NS after dehydration (0.7599). The aw of dehydrated apple slices was in the range 0.91101 to 0.641 with NS while the aw dehydrated apple product was in the range 0.8999 0.8405 with NNS. The TSS of fresh apple slices (11.5o bx) increased (34.68o bx) with ns after osmotic dehydration and decreased (6.02° bx) with NNS AA content of apple slices (31.67mg / l00g) significantly (p<0.05) decreased (9.58 mg / 100g) with NS and with NNS (8.93 mg /100g) after dehydration. Maximum decrease in AA was observed in sample T20 [sucrose: fructose (7:3)] and minimum in sample T24 [sucrose: fructose (7:3), AA and PMS], while with NNS maximum decrease was observed in sample Ns (cyclamate) and minimum in sample N4 (saccharine, AA and PS). Percent acidity of NS and NNS apple slices significantly (p<0.05) increased, while pH decreased during dehydration.

In third part of this study the influence of NS and NNS antioxidants and chemical preservatives (as used for guava and apple slices) was studied on the preservation of dehydrated 1M carrot slices. The aw of carrot slices (0.9599, fresh) significantly (p<0.05) decreased with NS (0.6499) after dehydration. The aw of dehydrated carrot slices was in the range 0.8919-0.6499 with NS while the aw of dehydrated carrot product was in the range 0.930-0.9001 with NNS. The TSS of fresh carrot slices (8° bx) increased (40.36° bx) with NS after osmotic dehydration and decreased (4.63° bx) with NNS. AA content of carrot slices (14.6 mg/ 100g) significantly (p<0.05) decreased (8.96 mg / 100g) with NS and with NNS (8.38 mg/ 100g) after dehydration. Maximum decrease in AA was observed in sample T20 [sucrose: fructose (7:3)] with and minimum in sample T4 (sucrose, CA and PMS), while with NNS maximum decrease was observed in sample No (saccharine) and minimum in sample N7 (cyclamate, AA and PMS). Percent acidity of NS and NNS carrot slices significantly (p<0.05) increased, while pH decreased after dehydration. During storage of these products no microbial growth was found in samples of NS +PMS; however, slight growth was observed in those samples treated with NNS despite adding PMS. The products which were treated with PS showed insignificant microbial control. Products which were given treatment with PMS, AA and CA retained maximum nutrients stability no microbial growth, best color, flavor, texture and overall acceptability during storage. NS products T19 [sucrose: glucose (7:3), AA and PMS] and T17 [sucrose: glucose (7:3), CA and PMS] were found to be the most acceptable dehydrated products to the taste panel.

Download Full Thesis
28315.32 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
1668.46 KB
2 1 Introduction 1
583.94 KB
3 2 Review Of Literature 15
1152.98 KB
4 3 Materials And Methods 44
356.77 KB
5 4 Results And Discussion 53
10263.69 KB
  4.1 Guava 53
  4.2 Apple 108
  4.3 Carrot 164
6 5 Summary 218
281.45 KB
7 6 Conclusions And Recommendations 224
66.54 KB
8 7 Literature Cited 226
560.17 KB
9 8 Appendices 240
13930.8 KB