1181

Journal of Protection, Vol. 70, No. 5, 2007, Pages 1181–1186 Copyright ᮊ, International Association for Food Protection

Microbiological and Color Aspects of Cooked Made from a Standardized Porcine Blood Cell Concentrate

BERNHARD NOWAK,* ADOLF HEISE,† NIKOLAI TARNOWSKI, AND THEDA VON MUEFFLING

Institute for Food Quality and Food Safety, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173 Hannover, Germany

MS 06-371: Received 10 July 2006/Accepted 12 November 2006 Downloaded from http://meridian.allenpress.com/jfp/article-pdf/70/5/1181/1681357/0362-028x-70_5_1181.pdf by guest on 27 September 2021 ABSTRACT

The objective of this study was to determine the potential for blood cell concentrates (BCCs) from pigs as an ingredient in food. Sausages were made for this study according to a basic recipe for a type of blood that is common in Germany. First, sausages were produced with rind and kettle broth only, and different amounts (2.5 to 31%) of standardized blood cell concentrate (s-BCC) were added (15% table salt [NaCl] and 25% content). Then, sausages were made with whole blood and compared with s-BCC sausages; both the BCC and blood had been pretreated either with NaCl or curing salt (nitrite). The impact of BCC and blood on the color (La*b*) of these rind sausages was determined. Finally, blood sausages were made with 12% s-BCC and either natural or extracts. These sausages were investigated microbiologically and compared to customary commercial blood sausage products (with whole blood) in terms of aerobic plate count (APC), Enterobacteriaceae, sulfite-reducing anaerobic bacteria, coagulase-positive staphylococci, and spore-forming bacilli. The de- sired color parameters (L, 34.5; a*, 17.8; and b*, 10.6) were obtained with the addition of about 12% s-BCC. Curing the blood or BCC beforehand had no significant (P Ͼ 0.05) influence on the color. The microbial counts of both the blood (APC, 4.4 log CFU/g) and the natural spices (APC, 6.6 log CFU/g) were relatively high. The spices were responsible for the relatively high microbial counts in the sausages, particularly the bacilli (6.4 log CFU/g). However, these counts were comparable to those found in commercial blood sausages. The bacteria introduced into the sausage by the blood had no significant impact on the bacterial counts of the end product. The bacterial loads of the sausages produced with 12% s-BCC and spice extracts were significantly lower (APC and bacilli, 2.0 log CFU/g) than those of the other blood sausages (APC, ϳ4.4 log CFU/g; bacilli, 3.2 to 4.0 log CFU/g).

Only a small fraction of the blood collected in slaugh- sausage are a low level of microorganisms and the color of terhouses is used for human consumption (3, 15). In fact, the product (1, 2, 15). The typical color is the result of the red blood cell concentrate (BCC) is even banned from the oxygenation (23) and oxidation of the heme group (specif- food chain in some countries (e.g., Germany). However, ically of the iron ion, Fe2ϩ to Fe3ϩ) (9), which are intro- this BCC has a high nutritive value and a microbiological duced into the sausage with the blood cells. Color is also status comparable to that of whole blood (16). Blood spoils affected by processing temperature (22); by the presence quickly and is subject to great variation in its initial micro- and amount of nitrite used as a curing salt (nitroso hemo- biological contamination (16, 17). To maintain the quality globin); and by the pH (2, 23). The addition of salt alone of blood or its cell concentrate until use, these substances is said to lead to brown-black (24) or grayish red (10) col- Њ must be stored at 3 C or should be preserved, such as by ors, but Stiebing (23) described only slight variations in red the addition of 15% table salt (NaCl) to the BCC (16). colors in nitrite-free and cured blood sausages. One of the oldest known sausage types is the black The aim of the present investigation was to show the produced from the collected blood of slaughtered potential for the use of BCCs in food products. Rind sau- animals (12, 23). Because of their high water activity sages were manufactured without and with various amounts (ϳ0.96 to 0.99) and pH values (6.2 to 7.3) in blood sau- of BCCs to determine the influence of BCCs on microbi- sages or blood pancakes (13, 20, 21, 25), these products ological status and color. Moreover, blood sausages were spoil rapidly. The microbiological quality of the product is produced with different amounts of standardized BCC (s- significantly affected by the initial bacterial load in the blood and in the spices and other ingredients (meat, , and BCC, 25% protein content and 15% NaCl) and with either rind) used (5, 25). Another crucial factor is good manufac- natural spices or spice extracts for a comparison (6) of their turing practice (6). Among the typical bacteria found in microbiological and sensory qualities with the rind sausag- blood sausages are bacilli, clostridia, Enterobacteriaceae, es and commercial blood sausage. and micrococci/staphylococci (5, 13, 19, 20). MATERIALS AND METHODS The two most important quality parameters of blood BCC collection and preparation. Porcine BCC was col- * Author for correspondence. Tel: ϩ49-511-856-7319, Fax: ϩ49-511-856- lected at a commercial slaughterhouse. The blood was collected 827319; E-mail: [email protected]. from pigs in a sticking carousel (RotaStick, Anitec, Malmø, Swe- † This article is dedicated to Adolf Heise, who died in June 2006. den) with hollow knives. Citrate (0.3 to 0.4% [wt/vol]; trisodium 1182 NOWAK ET AL. J. Food Prot., Vol. 70, No. 5

TABLE 1. Experimental design of the study and composition of the sausage variations produced

R1–R6: rind sausages S1, S2: blood sausages

Part 1A Part 1B Part 2

R1 R2 R3 R4 R5 R6 S1 S2

Rind sausage ingredients (% in final rind mass) Cooked rinds 47 47 47 47 47 47 47 47 Kettle broth 53 50.6, 46, 41, 36.5, 32, 27, 22 43, 38 43, 38 23, 8 23, 8 41 41 BCC pretreated with: 15% NaCl — 2.4, 7, 12, 16.5, 21, 26, 31 10, 15 — — — 12 12 15% curing salt — 10, 15 — — Downloaded from http://meridian.allenpress.com/jfp/article-pdf/70/5/1181/1681357/0362-028x-70_5_1181.pdf by guest on 27 September 2021 Whole blood pretreated with: 1% NaCl — — 30, 45 — 1% curing salt — — — 30, 45 Total (%) 100 100 100 100 100 100 100 100 Blood sausage ingredients (% in final sausage) Rind mass 44 44 Meat and fat 55 55 Natural spices 1— Spice extract —1 citrate and sodium chloride, 7:3; Fibrisol, Fibrisol Service, Vi- bath for between 75 and 90 min and then cut into 1-cm cubes. ernheim, Germany) was added to the blood as an anticoagulant. Back fat was cut into 0.5-cm pieces. The cut meat and back fat The blood flowed through cooled tubes toward a separator (Hank- were stored frozen in bags until use. kiija, Helsinki, , modified by Anitec) with approximately Some of the blood sausages (S1; Table 1) were produced with 500 plates turning at 1,450 rpm, and the resulting plasma and a natural spice mixture (Hannoversche Gewu¨rzmu¨hle, Hannover, BCC were stored in separate tanks. Cooling to ϩ2ЊC was contin- Germany) containing pepper (4.0 g/kg of sausage), nutmeg (1.0 ued inside the tanks. The BCC was transferred to sterile 1-liter g), pimento (1.0 g), cloves (0.5 g), caraway (1.0 g), celeriac (1.0 glass bottles and put into a cooler equipped with chilling aggre- g), and marjoram (1.5 g). Other blood sausages (S2; Table 1) were gates. A thermometer was inserted into one bottle of each trans- made with a mixture of extracts of the same spices (Ru¨ther Gew- porter for temperature recording during transportation. Upon ar- u¨rze, Holzwickede, Germany). The spices in the extract mixture rival at the laboratory, a portion of the BCC was used immediately were used in the same quantities as the natural spices. for the determination of protein content (Kjeldahl method). The Cleaned porcine colons were used as casings (Hannoversche rest of the BCC was kept at Յ4ЊC until microbiological analysis Gewu¨rzmu¨hle). the following day. Depending on the results of the protein determination, the Sausage production. Table 1 gives an overview of all the BCC was standardized to (i) 25 g of raw protein per 100 g of s- sausage variations produced (R1 through R6; S1 and S2) in the BCC with sterile physiological sodium chloride (NaCl) solution sequence (parts 1A, 1B, and 2) and the amounts of the various and then to (ii) 15 g of NaCl per 100 g of s-BCC with crystalline ingredients. sodium chloride (Merck, Darmstadt, Germany). All components In the first part of the study, sausages were made from a were thoroughly mixed by homogenization in sterile bags in a mass of rind and kettle broth milled in a colloid mill and filled laboratory blender (Stomacher 400, Seward, London, UK). The s- in casings (R1). At the same time, rind sausages were manufac- BCC was kept at room temperature (21ЊC) for 6 days until further tured with the addition of s-BCC (R2). Recipes for rind mass processing. All samples collected were subjected to the same pro- sausages (R1 through R6) were calculated to yield a final weight cedure. In some of the sausage variations with BCC (R4; Table of 850 g, and those for the blood sausages with meat and fat (S1 1), the NaCl was replaced with curing salt (ϳ500 ppm of nitrite and S2) were calculated to yield a final weight of approximately in salt; Akzo Nobel Salz, Stade, Germany); these sausages were 2,000 g. In part 1A, the following amounts of s-BCC were added also produced by the procedure described above. to the raw rind sausage mass: approximately 2.5% (wt/wt) s-BCC in raw rind sausage mass, 7, 12, 16.5, 21, 26, and 31%. All seven Collection and preparation of further raw materials. One s-BCC variations (R2) were produced 10 times, and the control day before the sausages were prepared, fresh whole pig blood was sausages with no s-BCC (0%, R1) were produced 12 times. The collected in the slaughterhouse in the same manner as the BCC. color of all rind sausages was determined. The results of this first Either approximately 1% NaCl or 1% curing salt was added; the part of the study (1A) indicated that the addition of approximately substrate was stored at ϩ2ЊC until use. 12 to 16.5% s-BCC to the rind sausage resulted in acceptable Pork belly and back were transported to the meat technology colors. After the conclusion of part 1A, sausages were therefore facilities in the institute, where the fat was removed in order to produced in part 1B containing 10 and 15% s-BCC (R3) (four obtain predominantly fat-free rinds, which were kept frozen until times each). The color of these sausages (R3) was then compared use. to that of the other six rind sausage variations: those containing Pork jowl and boneless shoulder meat from which all fat had (i) either 10 or 15% BCC mixed with 15% curing salt rather than been removed were cooked at between 90 and 95ЊC in a water NaCl (R4); (ii) either 30 or 45% whole blood mixed with 1% salt J. Food Prot., Vol. 70, No. 5 STABILITY OF COOKED SAUSAGES MADE FROM BLOOD CELLS 1183

Њ (R5); and (iii) either 30 or 45% whole blood mixed with 1% l’Eclairage norm light, D65,10 observer, measurement with gloss curing salt (R6) (part 1B). capture. In the second part of the study (see Table 1), commercial- type blood sausages were produced containing 12% s-BCC in the Statistical analysis. The statistical evaluations were per- blood rind mass and meat and fat chunks. Variations were pro- formed by the SAS program, version 8.2 (SAS Institute Inc., Cary, duced that contained either natural spices (S1) or spice extracts N.C.). The data with a Gaussian distribution were tested with SAS (S2). Microbiological testing was conducted on all ingredients procedures by t tests or the Wilcoxon signed-rank test for linked used, on the rind masses (both for the rind sausages without blood samples or by t tests or the Wilcoxon two-sample test for unlinked and those with 12% s-BCC), and on the finished sausages. The samples. blood sausages that were produced in the laboratory (S1 and S2) RESULTS AND DISCUSSION were compared with 11 blood sausages purchased at randomly selected retail outlets. Microbiological testing of the ingredients used for the On the day of production, the raw, defrosted rinds were production of the rind or blood sausages showed that the Њ cooked in a water bath at 75 C for approximately 4 to 5 h. After microbial counts were higher in the fresh, unpreserved Downloaded from http://meridian.allenpress.com/jfp/article-pdf/70/5/1181/1681357/0362-028x-70_5_1181.pdf by guest on 27 September 2021 cooking, the rinds were placed in a grinder (FW 82/0418, Bizerba, blood, the BCC, and the natural spices than in the other Balingen, Germany) with 3-mm holes in the breaker plate. Meat ingredients used (Table 2). The APC of freshly collected Њ and fat were heated for 10 min at 90 C in water in a kettle au- blood was 4.4 log CFU/g and mainly consisted of Entero- toclave (Korimat KA 200, Christian Wagner KG, Esslingen, Ger- bacteriaceae, sulfite-reducing bacteria, and some spore- many). The cooking water was then used as kettle broth. Kettle broth and the minced rinds were mixed after cooling to 60ЊC. If forming bacilli. Previous studies have found similar bac- the recipe included blood, it was added at this point. The mass teria predominating in blood (5, 13, 19, 20). Whole blood was again milled in a colloid mill (PUC-Viskosator, type JV 10, was contaminated only slightly less than BCC (log 4.43 Probst and Class, Rastatt, Germany). In part 2 of this study, the CFU/g). These findings are in agreement with the results meat, fat chunks, and spices were mixed manually with the blood of Nowak and von Mueffling (16) and Otto (17). If blood rind mass. Finally, all sausages were stuffed into natural casings. is to be kept with low numbers of microorganisms for more The sausages were then hung in the steam of the cooking chamber than 3 to 5 days at 2 to 4ЊC (14, 16), it should be subjected (FPC 100 with a DP03/MEDAP data processor, Fessmann, Win- to a preservation process. In the meat trade, it could be Њ nenden, Germany) and cooked to a final core temperature of 70 C difficult to maintain the product at 2 to 4ЊC over the whole held for 3 to 5 min. The core temperature was measured contin- storage period because of poor cooling facilities or frequent uously inside one sausage. handling outside cooling. Therefore, blood was preserved Microbiological testing. The following microbiological ex- by the addition of 15% NaCl (16). With this method of aminations were performed regularly on the raw materials, the preservation, there was, in fact, a decrease in the bacterial sausages made in the laboratory, and the commercial sausages: load of the BCC stored at 21ЊC for 6 days (Table 2). These APC (72 h, 30ЊC) on plate count agar (Merck); Enterobacteria- changes in APC and sulfite-reducing anaerobic bacteria be- Њ ceae (24 h, 37 C) on violet red bile dextrose agar (Oxoid, Wesel, tween the fresh, unpreserved BCC and the stored (for 6 Њ Germany); sulfite-reducing anaerobic bacteria (72 h, 37 C) on sul- days) s-BCCs are statistically significant (P Ͻ 0.05). These fite polymyxin sulfadiazine agar (Merck); coagulase-positive changes were probably due to the low water activity, which staphylococci (24 ϩ 24 h, 37ЊC) on Baird-Parker agar (Oxoid); brain heart infusion broth (Merck); BBL coagulase plasma (BBL, was shown in a previous investigation to be as little as 0.82, Becton Dickinson, Heidelberg, Germany); and spore-forming ba- and to the salt itself (16). All bacteria counts in the s-BCC cilli (sample dilution incubation for 10 min at 80ЊC, plate count (15% NaCl and 25% protein content) decreased during the agar with the addition of 1% glucose, 48 h, 37ЊC; microscopic 6-day storage at room temperature (21ЊC). determination of gram-positive rods). The rind sausages produced with or without s-BCC had APC counts of around 2 log CFU/g. Korkeala et al. (13) Chemical and physical determinations. Upon arrival in the found similar APC counts (ϳ2.0 to 4.3 log CFU/g) in laboratory, the raw protein content (%) of the BCC collected at cooked blood sausages. The bacteria introduced into the the slaughterhouse was determined by the Kjeldahl method (Kjel- datherm, Gerhardt, Bonn, Germany) with special flasks for ma- sausages by the different ingredients were mainly destroyed Њ terials with high amounts of protein (Juergens, Gehrden, Germa- during pasteurization at 70 C. In all our sausages, the APC ny). After heating and chemical pulping, the material was titrated was mainly composed of spore-forming bacilli. All other in a Vapodest analyzer (Gerhardt). For the calculation of protein bacteria tested (Enterobacteriaceae, sulfite-reducing anaer- content, the nitrogen was multiplied by 6.25 (4). obic bacteria, and coagulase-positive staphylococci) were A spectrophotometric device (CM-2002, Minolta Camera, at or below the detection limit in the sausages. This was Osaka, Japan) was used to determine the color of the surface of also reflected in the observation that there was no signifi- 10 areas evenly distributed on the surface of each fresh slice of cant difference in the microbial numbers between rind sau- each rind sausage. A mean value was immediately calculated from sages with or without the addition of s-BCC (Fig. 1), even the 10 results from each slice. This determination was carried out though the APC of the stored s-BCC was 3.6 log CFU/g. by the method of the Commission Internationale de l’Eclairage, However, the levels of the spore-forming bacilli also were which expresses the color impression in terms of three parameters: L (white–black), a* (red–green), and b* (yellow–blue) (11). Mea- below the detection limit in the stored s-BCC. Sausages surements were taken with a xenon lamp after calibration to a produced with spice extracts, meat, and fat chunks were white and red standard at a wavelength of 400 to 700 nm with a just as low in bacterial levels as the blood rind sausages resolution of 10 nm and a measuring sequence of 3 s (18). The without further ingredients, even though the APCs of the adjustments were as follows: Commission Internationale de meat chunks were ϳ3.3 log CFU/g. Here, too, the contam- 1184 NOWAK ET AL. J. Food Prot., Vol. 70, No. 5

TABLE 2. Microbiological testing of sausages and ingredientsa APC Enterobacteriaceae c.-p. staphylococci Clostridiab Bacilli

log CFU/g (ϮSD, max./min.)

Precooked rinds 2.00 Ͻ2.30 Ͻ2.00 Ͻ1.00 Ͻ2.00 (n ϭ 6) (Ϯ0.10, 2.30/1.47) Meat chunks 3.28 Ͻ2.30 Ͻ2.00 Ͻ1.00 2.30 (n ϭ 6) (Ϯ0.12, 3.86/1.30) (Ϯ0.02, 3.00/Ͻ2.0) Fat chunks 2.00 Ͻ2.30 2.00 Ͻ1.00 Ͻ2.00 (n ϭ 6) (Ϯ0.15, 2.60/1.00) (Ϯ1.00, 2.00/Ͻ1.0) Whole blood 4.40 3.30 1.78 2.65 2.30 (n ϭ 5) (Ϯ0.26, 4.70/4.20) (Ϯ0.22, 3.65/Ͻ2.3) (Ϯ0.33, 2.15/Ͻ1.0) (Ϯ0.27, 2.89/1.70) (Ϯ0.12, 2.70/2.00)

BCC 4.43 3.36 1.70 2.66 2.20 Downloaded from http://meridian.allenpress.com/jfp/article-pdf/70/5/1181/1681357/0362-028x-70_5_1181.pdf by guest on 27 September 2021 (n ϭ 5) (Ϯ0.25, 4.75/4.18) (Ϯ0.08, 3.71/Ͻ2.3) (Ϯ0.22, 2.00/Ͻ1.0) (Ϯ0.13, 2.95/1.48) (Ϯ0.14, 2.78/Ͻ2.0) s-BCC, 90 min 4.15 2.85 1.78 2.11 1.90 (n ϭ 5) (Ϯ0.25, 4.40/3.78) (Ϯ0.15, 3.40/Ͻ2.3) (Ϯ0.08, 2.18/Ͻ1.0) (Ϯ0.26, 2.28/1.30) (Ϯ0.12, 2.30/Ͻ2.0) s-BCC, 6 days 3.60 2.44 1.60 1.90 Ͻ2.00 (n ϭ 5) (Ϯ0.30, 3.78/3.00) (Ϯ0.84, 2.30/Ͻ2.3) (Ϯ0.30, 2.00/1.00) (Ϯ0.20, 2.20/1.30) Natural spices 6.64 2.41 Ͻ2.00 1.08 6.43 (n ϭ 6) (Ϯ0.49, 6.96/6.12) (Ϯ0.46, 2.48/Ͻ2.3) (Ϯ0.23, 1.51/Ͻ1.0) (Ϯ0.17, 6.83/5.70) Spice extracts 1.60 Ͻ2.30 Ͻ2.00 Ͻ1.00 Ͻ2.00 (n ϭ 8) (Ϯ0.40, 2.32/Ͻ1) a Geometric means of the amounts of different bacteria tested in the following: precooked rinds, meat chunks, fat chunks, freshly collected whole blood, freshly collected blood cell concentrate, standardized blood cell concentrate 90 min after the addition of 15% NaCl (s-BCC, 90 min) and 6 days after the addition of NaCl (s-BCC, 6 days), natural spice mix, and spice mix extract. APC, total aerotic plate count; c.-p., coagulase-positive staphylococci; max., maximum; min., minimum. b Clostridia: detected as sulfite-reducing anaerobic bacteria. ination of the ingredients had no significant influence on standable why blood sausages produced with natural spices the bacterial load of the prepared sausage. However, all our have high APCs and spore-forming bacilli counts, even af- ingredients were selected and handled carefully and had ter the heating process and even though they usually con- low microbiological levels. Nevertheless, the blood and tain only small amounts (ca. 1%) of the spices. The APC other ingredients do affect the hygiene and shelf life of the and the spore-forming bacilli count were considerably high- product (5, 25), as highly contaminated ingredients can er in blood sausages with natural spices than in all the other never result in a high-quality product. Low initial amounts sausages we produced. Natural spices are known to be reg- of bacteria in all ingredients are essential for a stable prod- ularly contaminated with high counts of spore-forming ba- uct. cilli (7). However, many butchers still use natural spices, With a count of 6.43 log CFU/g of bacilli (Table 2), even though extracts do clearly result in sausages with no the natural spices were the chief source of the bacterial load recognizable (aroma) difference to the naturally produced in blood sausages (Fig. 1). Spore-forming bacilli are typi- variants. Because of their reduced bacterial contamination, cally found in microbiological determinations of blood sau- spice extracts should be used in the manufacture of meat sages (13). The spore-forming capacity of bacilli enables products instead of natural spices (5). them to survive pasteurization (8). It is therefore under-

FIGURE 1. Microbiological test results for the different sausage types studied: total aerobic plate count (APC) and amount of ba- cilli (log CFU per gram; maximum, minimum) in rind sausages FIGURE 2. Changes in color values (L, a*, and b*) after the (with 0% s-BCC [n ϭ 12] or 12% s-BCC [n ϭ 10]); in blood addition of different amounts (%) of standardized blood cell sausages (standard recipe with s-BCC: with natural spices [n ϭ concentrate (s-BCC) to rind sausages (acceptable color areas: 10] or spice extract [n ϭ 16]); and in retail products (n ϭ 11). L, -·-·-·-; a*, -----). J. Food Prot., Vol. 70, No. 5 STABILITY OF COOKED SAUSAGES MADE FROM BLOOD CELLS 1185

TABLE 3. Mean color values (La*b*) of sausage variations: those produced with curing salt and those produced with different amounts (10 or 15%) of blood cell concentrate pretreated with 15% NaCl or 15% curing salt Type and amt of Pretreatment additive blood in sausage in blood n L value a* value b* value

Whole blood (30%) NaCl (1%) 9 32.1 Ϯ 0.7 14.7 Ϯ 1.2 8.7 Ϯ 0.8 Curing salt (1%) 10 32.5 Ϯ 1.4 15.4 Ϯ 1.9 9.3 Ϯ 0.9 Whole blood (45%) NaCl (1%) 4 29.5 Ϯ 1.1 11.7 Ϯ 2.0 6.7 Ϯ 1.3 Curing salt (1%) 4 29.8 Ϯ 1.8 11.9 Ϯ 1.7 6.6 Ϯ 1.1 BCC (10%) NaCl (15%) 4 36.7 Ϯ 1.4 18.3 Ϯ 1.2 11.6 Ϯ 0.8 Curing salt (15%) 4 36.6 Ϯ 1.4 16.8 Ϯ 0.9 11.5 Ϯ 0.7 BCC (15%) NaCl (15%) 4 31.1 Ϯ 1.3 16.8 Ϯ 1.4 9.8 Ϯ 0.8 Curing salt (15%) 4 34.1 Ϯ 1.3 15.6 Ϯ 1.3 10.0 Ϯ 0.8 Downloaded from http://meridian.allenpress.com/jfp/article-pdf/70/5/1181/1681357/0362-028x-70_5_1181.pdf by guest on 27 September 2021

The colors (La*b* values) determined on slices of sau- rind sausages were darker than the 16.5% s-BCC sausages sages produced with different amounts of added s-BCC (see in part 1B. Table 1) are shown in Figure 2. The sausages with no blood In Table 3, the rind sausages produced with 30 or 45% were very light (L, 76.3 Ϯ 3.0) and had low yellow values whole blood pretreated either with 1% NaCl or 1% curing (7.6 Ϯ 0.6) and no redness (Ϫ1.1 Ϯ 0.5). Adding various salt are compared with the sausages containing 10 or 15% amounts of s-BCC reduced lightness continuously to a s-BCC and pretreated either with 15% NaCl or 15% curing mean value of 29.6 (31% s-BCC in rind sausage). Redness salt. There were no statistically significant (P Ͼ 0.05) dif- rose with the addition of 2.5 and 7% s-BCC to the sausage ferences in the batches in which curing salt (nitrite) was (a*, 16.1 Ϯ 0.6 and 18.8 Ϯ 0.7, respectively) and then fell used instead of NaCl. The findings of Stiebing (23) and again continuously (31%; 14.9 Ϯ 0.5). Yellowness was fair- Mielnik and Slinde (15) are similar and also indicate that ly high in sausages with 2.5% s-BCC (b*, 15.3 Ϯ 0.8) in there was no significant color difference in the sausages comparison to sausages without blood; however, yellow- produced with blood and those produced with nitrite-cured ness decreased continuously with increasing amounts of s- blood. However, it was concluded in both studies that the BCC (31%; 8.4 Ϯ 0.4). There were significant differences process of blood curing had not been optimized and that a within each color parameter (P Ͻ 0.05). However, there different ratio of ascorbic acid to nitrite could result in bet- were no significant (P Ͼ 0.05) color changes after the sau- ter color. It has been stated that blood for blood sausages sages were stored for 6 days (data not shown). should be cured in order to achieve acceptable red colors Mielnik and Slinde (15) and Santos et al. (20) also and that grayish red (10) or brown-black (24) colors would describe the darkening of blood sausages with increasing otherwise result. In our investigation, the red color was amounts of blood. Overall, the color of our sausages ranged very similar with NaCl and curing salt. It was shown by from beige (2.5% s-BCC in the rind sausage) to bright red Nowak and von Mueffling (16) that blood cells treated with and from dark red to brownish red (31% s-BCC). The de- high amounts of NaCl keep their bright red color when sirable red color for blood sausages corresponds approxi- stored at room temperature for more than 20 days. The mately to L values of between 34 and 38 and a* values of color was similarly stable in the heated sausages. We there- between 17 and 19.5 (22–24). These were obtained with fore suggest that salt (NaCl), not nitrite, is the most im- the addition of between 12 and 16.5% s-BCC to the rind portant ingredient for stabilization of the iron and conse- sausages. The sausages with 16.5% s-BCC with an L value quently for the color of blood sausage. of 33 and an a* value of 17 were already a little out of the In conclusion, our results indicate that it is feasible to desired range (too dark), while those with the addition of use a BCC in a meat product both from the microbiological 7% s-BCC (L, 39; a*, 19) were a little too light. Therefore, and the sensory (color) point of view. Between 10 and 12% the addition of between 10 and 15% s-BCC to the sausages of an s-BCC can be used in blood sausages. The BCC does was considered optimal. The color values of 10% s-BCC not have to be cured to obtain the desired red color, for the rind sausages were also acceptable (L, 36.7; a*, 18.3), but addition of 15% NaCl is sufficient to stabilize the color. An the 15% s-BCC rind sausages in part 1B of this study were intended side effect is that the stabilized BCC can be kept darker (L, 31.1) than the 16.5% s-BCC sausages in part 1A. at room temperatures without spoiling for at least 6 days, These results were the reason for again adding 12% s-BCC and bacterial counts even decrease during this storage time. to the blood sausages in part 2 of this study. The increase It can thus be concluded that s-BCC is a useful ingredient in the brownish black color with the addition of more blood for meat products. to the rind mass was due to changes in the status of the heme iron. Heating causes oxidation from the ferrous to the ACKNOWLEDGMENTS ferric state, resulting in the brownish color (9). The more This article is dedicated to the former butcher of the Institute for blood iron the sausage contains, the more the dark color Food Quality and Food Safety, Adolf Heise, who died in June 2006. The predominates. Slight, unintentional variations in the cook- study was generously supported by funding from the Fritz-Ahrberg Foun- ing process might have been a reason why the 15% s-BCC dation, Hannover, Germany. We gratefully thank the slaughterhouse B. & 1186 NOWAK ET AL. J. Food Prot., Vol. 70, No. 5

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