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Technological feasibility of heat-irradiation combination treatments for low-acid food products
Pergamon PII:
Rod&. Phys. Chem. Vol. 48, No. 3, pp. 371-372, 1996 Copyright Q 1996 Published by Elsevier Science Ltd Printed in Great Britain. All rights merved s0969_806x@6)00047-3 0969-806X/% fl5.00 + 0.00
TECHNOLOGICAL FEASIBILITY OF HEAT-IRRADIATION COMBINATION TREATMENTS FOR LOW-ACID FOOD PRODUCTS A. MINNAAR, J. R. N. TAYLOR, N. N. DERSLEY Department of Food Science, Faculty of Biological and Agricultural South
and A. E. J. McGILL Sciences,
University
of Pretoria,
Africa
Combination processing is the purposeful use of two or more preservation techniques, where their combined effect can be synergistic in creating barriers or hurdles to microbial growth (Day, 1989). The amount of ionising irradiation needed to stcrilise low-acid vegetable and starch products (with and without sauces) commercially, generally impairs their sensorial and nutritive qualities, and the use of thermal processes to sterilise these products commercially, may also affect product quality adversely (Kan et al., 1957; Kempe et al., 1957; Kempe, 1960; Langerak and Bruurs, 1973). The use of heat and ionising irradiation in combination can be advantageous, principally by allowing the less severe use of any single treatment, with consequent improvement in product quality (Vas, 1981). A systematic approach to the establishment of optimised combination parameters for heatirradiation processing to produce high quality shelfstable, low-acid food products on which future combination processing research and development could be based, is reviewed. In the initial study, mushrooms were chosen as a model system for the following reasons: they are low acid foods (pH > 4.6), have a high intrinsic value and their sensory and nutritional quality is affected adversely by severe processing conditions (Minnaar et al., 1995). Based on gamma D,,values for irradiation and F,-values for heating, the following treatments were selected to produce shelf-stable mushrooms in brine (Minnaar et al., 1992a): Treatment 1: Target F,-value = 8 min; Treatment 2: Target F,-value = 2 min + 2.5 kGy (0°C); Treatment 3: Target F,-value = 1 min + 4.5 kGy (0°C); Treatment 4: Target F,-value = 0.5 min + 7.5 kGy (-40°C); Treatment 5: Target F,-value = 0.25 min + 10 kGy (-40°C); Treatment 6: Target F,-value = 0.125 min + 20 kGy (-40°C); Treatment 7: 45 kGy (-40°C). A deliberate attempt was made to explore the full spectrum of possibilities in applying heat processing only (Treatment I),
heat-irradiation combination processing (Treatments 2-6) and irradiation processing (Treatment 7) only. The effects of selected heat, heat-irradiation combination and irradiation treatments on the micro-biological stability and quality of shelfstable mushrooms in brine stored at ambient temperatures, are discussed. From our results it was concluded that the use of heat-irradiation combination treatments such as target F,value = 2 min + 2.5 kGy at O’C and/or target F,low value = 1 min + 4.5 kGy at O’C, favouring irradiation dose levels, offered a feasible alternative to thermally processed or radappertised mushrooms in brine from a quality point of view (Minnaar et al., 1995). In heat-irradiation combination studies of freezesensitive, low-acid starchy foods (e.g. rice), the minimum heat treatment required to render a product sufficiently cooked, should be combined with the maximum irradiation dose level that can be applied to the product (not exceeding 10 kGy), without affecting its sensory quality adversely (Minnaar et al., 1995). Based on results obtained from the mushroom study (Minnaar et al., 1992b; Minnaar et al., 1995), the following treatments were selected to produce shelf-stable rice: Treatment 1: Target F,value = 6 min; Treatment 2: Target F,-value = 2min + 2.5 kGy at O’C; Treatment 3: Target F,value = 1 min + 4.5 kGy at O’C; Treatment 4: Target F,-value = 3 min + 5.5 kGy at 0°C; Treatment 5: 45 kGy at -40°C. The effects of heat, irradiation and heatirradiation combination treatments on the microbiological safety, microstructure and consumer sensory acceptability and preference of rice are discussed. Our results showed that shclfstable rice produced by heat-irradiation combination treatments such as target F,-value = 2 min + 2.5 kGy, target F,-value = 1 min + 4.5 kGy and/or target F,-value = 3 min + 5.5 kGy offered 371
Abstracts
312 HEAT
IRRADIATION
PROCESSMa
PROC
a feasible alternative only to radappertised rice from the standpoint of quality. It was established that technical requirements for heat and irradiation processing of a long grain American rice cultivar oppose each other directly, thereby reducing the feasibility of using heatirradiation combination processing to produce shelfstable rice. REFERENCES
t.e%sevcre
Less-
I-
HEAT-IRRADIATION COhfBINATION -I TREATMEIvr
MicmbiobgicaUy
safe
Improved sensory quality, nnlritive value and txmmmu ooceptsbility.
Fig.
I. Rationale
for using heat-irradiation processing.
combination
Day B. P. F. (1989) European Food and Drink Rev. 18, 4-i. Kan B., Goldblith S. A. and Proctor B. E. (1957) Food Res. 22, 509. Kempe L. L., Graikoski J. T. and Bonventre P. F. (1957) Appl. Microb. 5, 292. Kempe L. L. (1960) Nucleonics 18, 108, 110, 112. Langerak D. and Bruurs M. F. J. (1973) Acta Alimenf. 2, 229. Minnaar A., De Bruyn I. and McGill A. E. J. (1992a) Lebensmirtel- WissenschaJ? und Technol. 25, 2, 173. Minnaar A. and McGill A. E. J. (1992b) LebensmittelWksenschajt und Technol. 25, 2, 173. Minnaar A. and McGill A. E. J. (1992~) LebensmitfelWissenschaf und Technol. 25, 2, 178. Minnaar A., Taylor J. R. N. and McGill A. E. J. (1995) Food Control 6, 3, 165. Vas K. (198 I) In Combination Processes in Food Irraaktion, Proceedings of an IAEA symposium, IAEA, Vienna, pp. 125-130.
Rod&. Phys. Chem. Vol. 48, No. 3, pp. 371-372, 1996 Copyright Q 1996 Published by Elsevier Science Ltd Printed in Great Britain. All rights merved s0969_806x@6)00047-3 0969-806X/% fl5.00 + 0.00
TECHNOLOGICAL FEASIBILITY OF HEAT-IRRADIATION COMBINATION TREATMENTS FOR LOW-ACID FOOD PRODUCTS A. MINNAAR, J. R. N. TAYLOR, N. N. DERSLEY Department of Food Science, Faculty of Biological and Agricultural South
and A. E. J. McGILL Sciences,
University
of Pretoria,
Africa
Combination processing is the purposeful use of two or more preservation techniques, where their combined effect can be synergistic in creating barriers or hurdles to microbial growth (Day, 1989). The amount of ionising irradiation needed to stcrilise low-acid vegetable and starch products (with and without sauces) commercially, generally impairs their sensorial and nutritive qualities, and the use of thermal processes to sterilise these products commercially, may also affect product quality adversely (Kan et al., 1957; Kempe et al., 1957; Kempe, 1960; Langerak and Bruurs, 1973). The use of heat and ionising irradiation in combination can be advantageous, principally by allowing the less severe use of any single treatment, with consequent improvement in product quality (Vas, 1981). A systematic approach to the establishment of optimised combination parameters for heatirradiation processing to produce high quality shelfstable, low-acid food products on which future combination processing research and development could be based, is reviewed. In the initial study, mushrooms were chosen as a model system for the following reasons: they are low acid foods (pH > 4.6), have a high intrinsic value and their sensory and nutritional quality is affected adversely by severe processing conditions (Minnaar et al., 1995). Based on gamma D,,values for irradiation and F,-values for heating, the following treatments were selected to produce shelf-stable mushrooms in brine (Minnaar et al., 1992a): Treatment 1: Target F,-value = 8 min; Treatment 2: Target F,-value = 2 min + 2.5 kGy (0°C); Treatment 3: Target F,-value = 1 min + 4.5 kGy (0°C); Treatment 4: Target F,-value = 0.5 min + 7.5 kGy (-40°C); Treatment 5: Target F,-value = 0.25 min + 10 kGy (-40°C); Treatment 6: Target F,-value = 0.125 min + 20 kGy (-40°C); Treatment 7: 45 kGy (-40°C). A deliberate attempt was made to explore the full spectrum of possibilities in applying heat processing only (Treatment I),
heat-irradiation combination processing (Treatments 2-6) and irradiation processing (Treatment 7) only. The effects of selected heat, heat-irradiation combination and irradiation treatments on the micro-biological stability and quality of shelfstable mushrooms in brine stored at ambient temperatures, are discussed. From our results it was concluded that the use of heat-irradiation combination treatments such as target F,value = 2 min + 2.5 kGy at O’C and/or target F,low value = 1 min + 4.5 kGy at O’C, favouring irradiation dose levels, offered a feasible alternative to thermally processed or radappertised mushrooms in brine from a quality point of view (Minnaar et al., 1995). In heat-irradiation combination studies of freezesensitive, low-acid starchy foods (e.g. rice), the minimum heat treatment required to render a product sufficiently cooked, should be combined with the maximum irradiation dose level that can be applied to the product (not exceeding 10 kGy), without affecting its sensory quality adversely (Minnaar et al., 1995). Based on results obtained from the mushroom study (Minnaar et al., 1992b; Minnaar et al., 1995), the following treatments were selected to produce shelf-stable rice: Treatment 1: Target F,value = 6 min; Treatment 2: Target F,-value = 2min + 2.5 kGy at O’C; Treatment 3: Target F,value = 1 min + 4.5 kGy at O’C; Treatment 4: Target F,-value = 3 min + 5.5 kGy at 0°C; Treatment 5: 45 kGy at -40°C. The effects of heat, irradiation and heatirradiation combination treatments on the microbiological safety, microstructure and consumer sensory acceptability and preference of rice are discussed. Our results showed that shclfstable rice produced by heat-irradiation combination treatments such as target F,-value = 2 min + 2.5 kGy, target F,-value = 1 min + 4.5 kGy and/or target F,-value = 3 min + 5.5 kGy offered 371
Abstracts
312 HEAT
IRRADIATION
PROCESSMa
PROC
a feasible alternative only to radappertised rice from the standpoint of quality. It was established that technical requirements for heat and irradiation processing of a long grain American rice cultivar oppose each other directly, thereby reducing the feasibility of using heatirradiation combination processing to produce shelfstable rice. REFERENCES
t.e%sevcre
Less-
I-
HEAT-IRRADIATION COhfBINATION -I TREATMEIvr
MicmbiobgicaUy
safe
Improved sensory quality, nnlritive value and txmmmu ooceptsbility.
Fig.
I. Rationale
for using heat-irradiation processing.
combination
Day B. P. F. (1989) European Food and Drink Rev. 18, 4-i. Kan B., Goldblith S. A. and Proctor B. E. (1957) Food Res. 22, 509. Kempe L. L., Graikoski J. T. and Bonventre P. F. (1957) Appl. Microb. 5, 292. Kempe L. L. (1960) Nucleonics 18, 108, 110, 112. Langerak D. and Bruurs M. F. J. (1973) Acta Alimenf. 2, 229. Minnaar A., De Bruyn I. and McGill A. E. J. (1992a) Lebensmirtel- WissenschaJ? und Technol. 25, 2, 173. Minnaar A. and McGill A. E. J. (1992b) LebensmittelWksenschajt und Technol. 25, 2, 173. Minnaar A. and McGill A. E. J. (1992~) LebensmitfelWissenschaf und Technol. 25, 2, 178. Minnaar A., Taylor J. R. N. and McGill A. E. J. (1995) Food Control 6, 3, 165. Vas K. (198 I) In Combination Processes in Food Irraaktion, Proceedings of an IAEA symposium, IAEA, Vienna, pp. 125-130.