Impact of frozen storage and defrosting on the quality and ...Impact of frozen storage and...
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Impact of frozen storage and defrosting on the quality and safety of bakery products F. Van Bockstaele 1,2 , E. Debonne 1,2,3 , K. Wagemans 4 , I. De Leyn 1,2 , S. Samapundo 1,3 , A. Vroman 1,3 , M. Eeckhout 1,2,3 1 Ghent University, Faculty of Bioscience Engineering, Departement of Applied Biosciences, Valentin Vaerwyckweg 1, B-9000, Ghent 2 Laboratory of Cereal Technology - 3 Laboratory of Applied mycology 4 Federatie van Grote Bakkerijen in België, vzw-asbl, Belgium Problem setting EU regulation No. 1169/2011 states that for foods that have been frozen before sale and which are sold defrosted, the name of the food shall be accompanied by the designation ‘defrosted’. This requirement does not apply for foods for which defrosting has no negative impact on the safety or quality of the food, such as bakery products. However, producers should be able to clearly show that defrosting has no negative impact on the quality and safety of the bakery products. Goal The impact of temporary frozen storage and defrosting on the quality and safety of a selection of industrially produced bakery products (whole wheat bread, sandwiches, sponge cake (with cream and fruit filling), bake-off bread and cherry pie) was studied in comparison with non-frozen products. Conclusion The impact of temporary frozen storage of bakery products on product quality and safety was not always negative or even visible. For bread, the impact on quality was minimal and led to a decrease in microbial load. A significant reduction in microbial load was also found for sandwiches at the end of the shelf life time. Safetywise, the impact of temporarily frozen storage of the tested bakery products was negligible or even improved. The main impacts of temporarily frozen storage on product quality were reported on sandwiches and cherry pie. Despite of the fact that differences in quality were perceived, the consumer’s acceptability of the products did not significantly decrease. It could be concluded that the impact of temperarily frozen storage of bakery products can not be catalogued as being negative. Water activity (a w ) (25 °C) No significant differences between fresh and frozen products of the following categories were reported: bread, sponge cake, bake-off bread and cherry pie. Only for sandwiches, frozen storage impacted the a w of the crust on T0 (delivery date of sandwiches, either fresh or frozen). No significant difference remained visible after 4 days (T0 + 4d) (crust a w ≈ 0,921). . Texture of bread products The impact of frozen storage and defrosting on the crumb of the whole wheat bread, sandwich and bake-off bread was investigated using a Texture Analyzer (Texture Profile Analysis – TPA). a w sandwich Fresh T0 Frozen T0 Upper crust 0,921 ± 0,008 0,878 ± 0,022 Bottom crust 0,918 ± 0,003 0,898 ± 0,015 Safety : fresh product : frozen + defrosted before T0 : Upper limit of acceptibility : significant difference between fresh and frozen product T0 : Delivery date (fresh or frozen) Challenge test with spoilage fungi No significant differences were observed between fresh and frozen bakery products in a challenge test. Each bakery product was inoculated with specific mould spore solutions and incubated for a selected time. The number of incubation days needed for growth of the microorganisms was recorded. Bakery product Organism Incubation (days) Bread crust Penicillium paneum >7 Bread crumb 3 Sandwiches 7 Sponge cake Eurotium amstelodami >15 Cherry pie 7 Bakery product Parameter Fresh Frozen Fresh Frozen Bread (S = 3 d) T0 T0 + S Hardness (g) 487 ± 63 a 480 ± 40 a 541 ± 48 a 538 ± 40 a Cohesion (-) 0,75 ± 0,01 a 0,71 ± 0,01 b,c 0,73 ± 0,01 a,b 0,69 ± 0,01 c Bake-off bread (S = 34 d) Hardness (g) 378 ±96 a 441 ± 83 a 367 ± 46 a 411 ± 81 a Cohesion (-) 0,80 ± 0,02 a 0,78 ± 0,02 a 0,83 ± 0,01 b 0,82 ± 0,01 b Sandwich (S = 4 d) Hardness (g) 240 ± 33 a 236 ± 39 a 419 ± 46 b 428 ± 37 b Cohesion (-) 0,63 ± 0,02 a 0,55 ± 0,04 b 0,50 ± 0,02 c 0,43 ± 0,02 d Total plate count measurement Sensorial evaluation The sensorial evaluation was performed by a triangle test. The results show that for some bakery products a difference between fresh and frozen/defrosted was observed. However this difference was not always perceived as negative as for some products the acceptability did not decrease. Differences between fresh and frozen products could be due to a batch effect. • Numbers with equal letters within the same parameter are not significantly different (SPSS Anova, α=0,05) • T0: delivery date of the product, either fresh or frozen • S: number of storage days, depending on the product Significant difference? Acceptability (%) Bakery product @ T0 @T0 + S @ T0 @ T0 + S Bread (S = 3 d) No No 79 61 Bake-off bread (S = 34 d) No No 87 70 Sandwich (S = 4 d) Yes No 92 100 Sponge cake (S = 2 d) Yes Yes 80 94 Cherry pie (S = 4 d) No Yes 79 83 Quality 0 5 10 15 20 25 30 35 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 -100 Force (g) Time (sec) 1 2 3 4 5 6 1 F 2 F Force (g) Time (sec) Legend Sponge cake
Transcript of Impact of frozen storage and defrosting on the quality and ...Impact of frozen storage and...
Impact of frozen storage and defrosting on the qualityand safety of bakery products
F. Van Bockstaele1,2 , E. Debonne1,2,3, K. Wagemans4, I. De Leyn1,2, S. Samapundo1,3, A. Vroman1,3, M. Eeckhout1,2,3
1 Ghent University, Faculty of Bioscience Engineering, Departement of Applied Biosciences, Valentin Vaerwyckweg 1, B-9000, Ghent2 Laboratory of Cereal Technology - 3 Laboratory of Applied mycology
4 Federatie van Grote Bakkerijen in België, vzw-asbl, Belgium
Problem settingEU regulation No. 1169/2011 states that for foods that have been frozen before sale and which are sold defrosted, the name of the food shall be accompanied by the designation‘defrosted’. This requirement does not apply for foods for which defrosting has no negative impact on the safety or quality of the food, such as bakery products. However, producersshould be able to clearly show that defrosting has no negative impact on the quality and safety of the bakery products.
GoalThe impact of temporary frozen storage and defrosting on the quality and safety of a selection of industrially produced bakery products (whole wheat bread, sandwiches, sponge cake (with cream and fruit filling), bake-off bread and cherry pie) was studied in comparison with non-frozen products.
ConclusionThe impact of temporary frozen storage of bakery products on product quality and safety was not always negative or even visible. For bread, the impact on quality was minimal and led to a decrease in microbial load. A significant reduction in microbial load was also found for sandwiches at the end of the shelf life time. Safetywise, the impact of temporarily frozen storage of the tested bakery products was negligible or even improved.
The main impacts of temporarily frozen storage on product quality were reported on sandwiches and cherry pie. Despite of the fact that differences in quality were perceived, the consumer’s acceptability of the products did not significantly decrease. It could be concluded that the impact of temperarily frozen storage of bakery products can not be catalogued as being negative.
Water activity (aw) (25 °C)
No significant differences between fresh and frozen products of the following categories were reported: bread, sponge cake, bake-off bread and cherry pie.
Only for sandwiches, frozen storage impacted the aw of the crust on T0 (delivery date of sandwiches, either fresh or frozen). No significant difference remained visible after 4 days (T0 + 4d) (crust aw ≈ 0,921).
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Texture of bread products
The impact of frozen storage anddefrosting on the crumb of the whole wheat bread, sandwich andbake-off bread was investigatedusing a Texture Analyzer (TextureProfile Analysis – TPA). aw sandwich Fresh T0 Frozen T0
Upper crust 0,921 ± 0,008 0,878 ± 0,022
Bottom crust 0,918 ± 0,003 0,898 ± 0,015
Safety
Legend:Blue: : fresh product
Yellow: : frozen + defrosted before T0
: Upper limit of acceptibility
: significant difference between fresh andfrozen product
T0 : Delivery date (fresh or frozen)
Challenge test with spoilage fungi
No significant differences were observed between fresh and frozen bakery products in a challenge test. Each bakery product was inoculated with specific mould spore solutions and incubated for a selected time. The number of incubation days needed for growth of the microorganisms was recorded.
Bakery product
Organism Incubation(days)
Bread crust Penicillium paneum >7
Bread crumb 3
Sandwiches 7
Sponge cake Eurotium amstelodami
>15
Cherry pie 7
Bakery product Parameter Fresh Frozen Fresh Frozen
Bread(S = 3 d)
T0 T0 + SHardness (g) 487 ± 63 a 480 ± 40 a 541 ± 48 a 538 ± 40 a
Cohesion (-) 0,75 ± 0,01 a 0,71 ± 0,01 b,c 0,73 ± 0,01 a,b 0,69 ± 0,01 c
Bake-off bread(S = 34 d)
Hardness (g) 378 ±96 a 441 ± 83 a 367 ± 46 a 411 ± 81 a
Cohesion (-) 0,80 ± 0,02 a 0,78 ± 0,02 a 0,83 ± 0,01 b 0,82 ± 0,01 b
Sandwich(S = 4 d)
Hardness (g) 240 ± 33 a 236 ± 39 a 419 ± 46 b 428 ± 37 b
Cohesion (-) 0,63 ± 0,02 a 0,55 ± 0,04 b 0,50 ± 0,02 c 0,43 ± 0,02 d
Total plate count measurement
Sensorial evaluation
The sensorial evaluation was performed by a triangle test. The resultsshow that for some bakery products a difference between fresh andfrozen/defrosted was observed. However this difference was notalways perceived as negative as for some products the acceptability didnot decrease. Differences between fresh and frozen products could bedue to a batch effect.
• Numbers with equal letters within the same parameter are not significantly different (SPSS Anova, α=0,05)• T0: delivery date of the product, either fresh or frozen• S: number of storage days, depending on the product
Significant difference? Acceptability (%)
Bakery product @ T0 @T0 + S @ T0 @ T0 + S
Bread(S = 3 d)
No No79 61
Bake-off bread(S = 34 d)
No No87 70
Sandwich(S = 4 d)
Yes No92 100
Sponge cake(S = 2 d)
Yes Yes80 94
Cherry pie(S = 4 d)
No Yes79 83
Quality
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0
-100
Force (g)
Time (sec)
1 2 3 4 5 6
1F
2FForce (g)
Time (sec)
Legend
Sponge cake
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