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Influence of protein isolate from lupin seeds (Lupinus albus ssp. Graecus) on processing and quality characteristics of frankfurters
Mear Science, Vol. 42, No. 1, 19-93, 1996 Elsevier Science Ltd Printed in Great Britain 0309-1740/96/$9.50+ .OO ELSEVIER
0309-1740(95)00013-5
influence of Protein Isolate from Lupin Seeds (Lupinus albus ssp. Graecus) on Processing and Quality Characteristics of Frankfurters Silvana Alamanou,
a * J. G. Bloukas,b dz G. Doxastakis”
E. D. Panera
“Laboratory of Food Chemistry and Technology, Faculty of Chemistry, Aristotle University of Thessaloniki, GR 540 06, Thessaloniki, Greece bLaboratory of Food Science and Technology, Faculty of Agriculture, Aristotle University of Thessaloniki, GR 540 06, Thessaloniki, Greece (Received 15 September 1994; revised version received 26 November accepted 15 February 1995)
1994;
ABSTRACT Lupin protein isolate (92% protein) from seeds of Lupinus albus ssp. Graecus (LSPI) was used as powder ingredient for the manufacture offrankfurters at levels 0, 1, 2 and 3% of the formulation weight. Additional 1% water was added during batter formulation to each 1% protein used. LSPI increased (P < 0.05) the pH and viscosity of batter and reduced the jelly separation. Increasing the LSPI level resulted in higher (P < 0.05) processing yield and lower (P < 0.05) purge accumulation, redness and visual colour scores and hardness of frankfurters. Signtjicant differences in overall acceptability were not found among the control and frankfurters with 1% and 2% LSPI. Frankfurters with 3% LSPI were judged as unacceptable. Incorporation of LSPI at 1% level either in hydrated form or as stabilizer in pre-emulsified fat improved the processing characteristics and overall acceptability of frankfurters made with LSPI as powder ingredient and did not affect the color and texture.
INTRODUCTION The manufacture of cornminuted meat products is dependent upon the formation of a functional protein matrix within these products (Schmidt et al., 1981). Meat proteins are well recognized for their functional properties in formation and stabilization of the matrix. The relevant functional properties include the emulsifying capacity, emulsion stability, water binding, gelation and cohesion of particles. These functional properties are interrelated and are determined by the quantity, composition, conformation and physical properties of the muscle proteins present in the cornminuted meat product (Mittal & Usborne, 1985). However, the increasing cost of animal protein and the fact that the availability of meat is *Author to whom correspondence
should be addressed. 79
80
S. Alamanou et al.
scarce in some countries have urged researchers to explore the possibilities of utilizing different types of unconventional protein sources in comminuted meat products in order to reduce the formulation cost. Plant proteins have the advantage that they can be produced in large quantities and have low cost. The suitability of plant proteins for the production of comminuted meat products is related to such functional properties as water retention, fat-binding, emulsifying capacity, sensory properties, storage stability and nutritional quality of finished product. Soy proteins have received most attention because of their availability, low price, nutritional value (Young et al., 1979) and unique functional properties. Soy proteins have the ability to enhance and stabilize fat emulsion, improve viscosity, impart texture upon gelation following cooking, and improve moisture retention and overall yields. The ability of soy proteins to bind and retain meat juices enhances mouthfeel and flavor in meat emulsions (Kinsella, 1979). However, soy products often have a characteristic off-flavor, which has been described as ‘beany’ or ‘cereal-like’ and a bitter and astringent off-aroma (Kinsella & Damodaran, 1980; Williams & Zabik, 1975). To minimize the soy flavor, spices and seasonings should be added to the hydration water and allowed the hydrated mixture to stand at low temperature for flavor penetration into soy, rather than the meat (Willing, 1974). Lecomte et al. (1993) found that the incorporation of soy proteins, in formulations of frankfurters as pre-emulsified fat, resulted in a reduction of specific soyabean off-flavor and off-aroma. Sunflower offers excellent potential as a plant protein source due to its high protein content and to the fact that it ranks as the second major oilseed crop in the world. Lin et al. (1975) found that the addition of sunflower products (flour and protein concentrates) to wieners provided better emulsion stability than did the soy supplements. Wills & Kabirullah (1981) prepared beef sausages with the addition of sunflower flour and resulted in a product which was equally acceptable to the taste panel to the sausages prepared with gluten and soy protein isolate. However, sausages prepared with sunflower protein isolate were the least acceptable due to a dark coloration. Padua (1983) investigated the effect on acceptability of replacing 0, 20, 30 and 40% meat in loaves with hydrated textured defatted sesame flour. The loaves with 30% meat replaced by the defatted sesame flour were scored higher than the rest of the loaves, even higher than all-meat loaves. Cruz & Hedrick (1985) prepared fermented salami containing 0, 9, 18 and .27% defatted sesame flour and found that it can be used at either 9 or 18% level without detrimental effect upon sensory attributes of the product. Fresh skinless sausages were prepared by Verma et al. (1984~) in which some of the meat was replaced on a protein-to-protein basis by chickpea flour. The results showed that levels of substitution up to 30% protein replacement could be made without adversely affecting product acceptability. Later work, however, showed that it was necessary to heat chickpea flour to 80°C for 1 h to prevent discoloration of raw sausages caused by lipid peroxidation on storage (Verma et al., 1984b). Lin & Zayas (1987) incorporated corn germ protein in comminuted meat products as an ingredient (4%) and as stabilizer (2%) in pre-emulsified fat (PEF). They found that corn germ protein could be used as an ingredient at 3.5% and as stabilizer at 2% in PEF to increase yield while maintaining textural and other qualities similar to those of the whole meat product. In another work Zayas & Lin (1988) developed a process for incorporation of defatted corn germ protein in
Influence of protein isolate on processing and quality of frankfurters
81
frankfurters. They found that using it at 3% level resulted in an improvement of the quality characteristics and increased the yield of the product. Finaly, Gnanasambandam & Zayas (1992) compared the functionality of wheat germ protein in frankfurters as compared with corn germ and soy proteins. They found that wheat germ protein flour is a potential non-meat protein additive that can be utilized as an extender in comminuted meat products. At the 3.5% level it affected in the same way the quality characteristics of frankfurters as soy flour and corn germ protein flour. Lupin is a very well known legume in Europe, especially in Mediterranean countries, in South America (Chile and Peru), as well as in Australia and New Zealand, where it was cultivated for centuries. The great advantage of the seed is the elevated protein content which ranges between 31% and 42% in the different lupin species. This high protein concentration is sometimes superior to that of soy and moreover lupin protein amino acid pattern is comparable to that of soy (Cerletti & Duranti, 1979). Gross et al. (1983) found that lupin based dishes, derived from Lupinus mutabilis cultivated in Peru, have been well accepted according to a test of acceptability performed with children from 8 to 15 years of age over a 3-year period. No research has been conducted using the lupin protein isolate as an additive in comminuted meat products. The object of this study was (a) to evaluate the lupin protein isolate from seeds of Lupinus albus ssp. Graecus, as a potential non-meat protein additive that can be utilized as an extender in comminuted meat products, and (b) to establish its influence, as powder ingredient, hydrated or as a stabilizer in pre-emulsified fat on processing and quality characteristics of frankfurters.
MATERIALS
AND
METHODS
Meat source Frozen lean beef, lean fresh pork and fresh pork backfat were obtained from a local meat market. Partially thawed beef and fresh pork were trimmed of separable fat to provide extra lean meats. The lean meat and the pork backfat were separately ground through a 12 mm plate and then through a 3 mm plate. The ground meats and pork backfat were vacuum packaged in moisture-proof plastic bags and frozen at -20°C for l-2 weeks until product formulation. Representative samples were analyzed for moisture, fat and protein (AOAC, 1984) prior to freezing. All raw materials were tempered at 0°C for 24 h prior to use. Lupin seed protein isolate Lupin seeds (Lupinus albus ssp. Graecus) were provided from Lasithi, Crete, Greece. The dry seeds were ground in a Tomas-Wiley mill (model ED-5 USA) to pass a 100 mesh screen. In this way the protein extraction from the flour may exceed 96% during the solubilisation by the alkali (Leonard et al., 1976). The flour was then defatted with n-hexane (1:3 w/v), by the Soxhlet method, at a temperature of about 40°C until the fat content was reduced to about 5% (Christie, 1982). The solvent residues were then removed by drying the flour at room temperature.
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S. Alamanou et al.
The defatted flour was mixed with distilled water (1: 10 w/v) and the suspension adjusted to pH 9.0 with alkali (1N NaOH) in order to extract the proteins. The slurry was stirred for 30 min at 20°C. After that the insoluble residue (water insoluble polysaccharides plus residual protein) is separated by filtering and centrifuging at 5 000 g for 20 min. The residue was mixed with distilled water (1:5 w/v) and re-extracted under the same conditions. The supernatants were precipitated at pH 4.5 with food grade acid (1N HCI) and centrifuged at 5000 g for 20 min. The precipitate was adjusted to pH 7.0 for neutral protein isolate and freeze-dried (Alamanou & Doxastakis, 1994). The mean composition of lupin seed protein isolate (LSPI) used was 92.0% protein, 5.4% moisture, 0.5% fat and 2.1% ash. Experiment a
In this experiment the lupin seed protein isolate (LSPI) was used as a powder ingredient for the manufacture of frankfurters at four levels: 0, 1,2 and 3 % of the formulation weight. The control treatment (0% LSPI) was formulated so that the amount of added water to be 28%of batter and the composition of final product aproximately 11% protein and 27% fat. All other treatments were formulated by the addition of 1% extra water to every 1% protein used (Lin & Zayas, 1987; Gnanasambandam & Zayas, 1992). Experiment b
In this experiment lupin seed protein isolate (LSPI) was used at 1% level as powder ingredient, hydrated and as stabilizer in pre-emulsified fat (PEF) in comparison to the control treatment (0% LSPI) as in previous experiment. The treatments with LSPI were formulated by the addition of 1% extra water to every 1% protein used. The hydration of LSPI was done by mixing with four parts of water (ratio 1:4) and the slurry was kept in a cooler at + 4°C for 20-24 h prior to use. The PEF sample was made following the procedure of Lecomte et al. (1993). The mixture of LSPI (1% of the formulation weight) and water (half the added water of the formulation) was blended in a Braun blender at high speed for 2 min. The protein slurry was incubated for 30 min in a water bath at 80°C. Pork backfat was softened and partially melted by warming in a water bath with boiling water and immediately was added slowly and emulsified in the blender with the protein slurry at high speed for 5 min. The PEF was kept in a cooler at + 4°C for 24 h prior to use. Frankfurter manufacture
The partially thawed meat was chopped for 2-3 s in a Laska 30 L cutter at low speed and then mixed with the following ingredients, expressed as percentage of the batter weight: 1.7% salt, 0.02% sodium nitrite, 0.3% polyphosphates and 0.75% seasoning. The mixed meat was dry chopped for 2&30 s, 0.08% sodium ascorbate was added, diluted in water, and the chopping continued with the addition of one-third of total added water (ice chips) until a temperature of + 3°C was reached. At this point the LSPI as powder, hydrated or as stabilizer in PEF, where needed, was mixed with the chopped meat together with the remainder ice/
Influence of protein isolate on processing and quality of frankfurters
83
water and the thawed pork backfat and the batter was chopped at high speed until the final temperature reached 12°C. Immediately after chopping the batter of each treatment was vacuum-stuffed into 24 mm diameter Nojax cellulose casings. Each treatment was handlinked at 15 cm intervals and the frankfurters were heat processed and smoked in a smoke house to internal temperature 72°C for 5 min. The frankfurters were showered for 15 min and chilled at + 2°C for 24 h. After chilling, the frankfurters were handpeeled, vacuum packaged (vacuum level 650 mm Hg) in film pouches with a reported oxygen permeability rate of 116 cm3/m2/24 h/l atm (23°C 0% RH) and stored in the dark in a cooler at + 4°C until subsequent analysis. Chemical analysis
Representative samples from each treatment were homogenized and analyzed, prior to vacuum packaging, for percentage moisture, fat (ether-extractable), protein and ash according to standard AOAC (1984) procedure. All analyses were performed in duplicate. pH measurement
pH was determined with a WTW digital pH meter in a slurry made by blending 20 g batter or final product with 80 ml distilled water in a Braun mixer for 1 min at high speed. Data are means of two measurements. Batter viscosity
Viscosity was measured after keeping the batter for 4-5 h in a and tempering for 1 h to ambient temperature. The measurement a Brookfield digital viscometer, model DV-II, set at 2.5 rpm and spindle No. 5. The readings were noted after 30 s shearing time centipoises. Data are means of the first five readings on a 100 with batter.
cooler at +2”C was made with equipped with a and recorded in ml beaker filled
Jelly and fat separation
The jelly and fat separation was measured by the procedure described by Bloukas & Honikel (1992). At the end of the comminution process three preweighed cans (size 58 x 73 mm) were filled with batter. The cans were closed and heated for 35 min in a boiling water bath (core temperature about 9O’C). After cooling in running tap water the cans were stored at 4°C for 24 h. After warming up the cans in a water bath at 45°C for 1 h they were opened and the fluid of each can was collected in a 100 ml volumetric cylinder. The fluid jelly and fat, separated in the volumetric cylinder, was measured in ml and calculated as a percent of the original weight of batter. The mean value of three cans was taken for each treatment. Processing yield
Frankfurters were weighed before heat processing and smoking and after chilling at + 2°C for 24 h. The processing yield (%) was determined from their weights.
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Purge accumulation Two vacuum-packages (about 25&300 g each) per treatment were used to determine purge accumulation of frankfurters the 1st week of storage at 4°C. Before packaging each link of frankfurters was dried with paper tissue and all links per package were weighed. After removing sausages from the package each link was again dried with paper tissue and all links per package were reweighed. Purge accumulation was determined from the difference in weights between the two measurements expressed as percentage of initial weight. Colour measurement Colour measurements were performed on the 1st week of refrigerated (4°C) storage. A Trucolour Neotec calorimeter was used to measure the colour numbers L, a and b (Hunter color system) at the skin of frankfurters. The instrument was standardized using a white ceramic tile calibrated to tristimulus values of L= + 96.0, a = - 1.03 and b = + 2.4. Two frankfurters per treatment were used. Four measurements were taken per link and data are means of eight measurements. Texture profile analysis An Instron Universal Testing Machine, model 1125, was used to conduct texture profile analysis, as described by Bourne (1978), the 1st week of refrigerated (4°C) storage. Samples were prepared by steeping frankfurters in boiling water for 2 min and cooling to ambient temperature. Four 20 mm long sections per treatment were axially compressed by a two cycle compression test to 75% of original height. Force-time deformation curves were recorded at a crosshead speed 5 cm/ min, chart speed 5 cm/min and full-scale 50 kg. Texture variables of force and area measurements were: FF = force to fracture; Fi = maximum force for first compression; F2 = maximum force for second compression; Ai = total energy for first compression; AZ = total energy for second compression; cohesiveness = AZ/ Ai; and gumminess = FixAz/Ai. Springiness (S) was calculated as the percentage of initial height recovered after the first compression, and chewiness = F1xA2/AlxS. Peak areas were determined by using the Ladd Graphic Data Analyzing System. Sensory evaluation A 15-member untrained panel evaluated frankfurters during the 1st week of storage for colour and overall acceptability on a 6-point hedonic scale (6=like extremely, 1 = dislike extremely). Panel members were selected from students, staff and faculty of the Laboratory of Chemistry and Technology. Colour acceptability was evaluated during display of two links from each treatment. Samples for overall acceptability were prepared by steeping frankfurters in boiling water in individual pans for 2 min. Warm 2.5 cm long pieces from each treatment were randomly distributed for evaluation. The panelists were instructed to evaluate the appearance, the texture, the flavor and the juiciness of the products and express their overall acceptability.
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Infuence of protein isolate on processing and quality of frankfurters
Statistical
analysis
All paraStatistical analysis was performed using the MSTAT _. -. (1985) program. _ __ _. _ meters studled were analyzed by one-way analysis of variance. Means were compared by using the LSDo,oS test. Simple correlations were determined between selected response variables.
RESULTS
AND
DISCUSSION
Effect of LSPI level on processing and quality characteristics
of frankfurters
The approximate composition of frankfurters, as affected by the LSPI level, is given in Table 1. The higher the LSPI level the higher (P < 0.05) the protein and moisture content of frankfurters. The mean protein content of frankfurters with LSPI was lower than the targeted values. The control treatment had higher (P < 0.05) fat content and lower (P < 0.05) ash content than the treatments with LSPI. No differences (P > 0.05) in fat and ash content were found between the treatments with LSPI. The effect of LSPI level on batter characteristics, processing yield and purge accumulation is given in Table 2. The addition of LSPI increased the pH and the viscosity of the batters. The treatment with 3% LSPI had a significantly higher (P < 0.05) batter pH and viscosity than the control treatment. These results are TABLE 1 Effect of LSPI Level on Approximate Composition LSPI
level
(%)
0 1 2 3
Watelm
(%)
Moisture
28 29 30 31
(%)
Protein
56.5’ 57.2bc 57.46’ 58.0b
of Frankfurters (%)
Ash (%)
Fat (%)
29.gb 28.3” 27.4” 25.9”
11.3e 11.8d 12.6’ 13.56
2.3’ 2.5b 2.5b 2.5b
OWater added during formulation. Control treatment formulated for 28% added 1% water was added with every 1% protein addition. &‘Means in the same column with different superscripts are different (P < 0.05). TABLE 2 Effect of LSPI Level on Batter Characteristics, Processing LSPI level
Batter (PH)
ml 0 1 2 3
“bMeans
6.47b 6.53”b 6.6OOb 6.68”
water;
Yield and Purge Accumulation
Brookfield viscosity
Jelly separation
Fat separation
Processing yield
Finished product
Purge accumulation
(CP x I@)
I%)
(%)
(%)
(PH)
(%)
0.57 0.67 0.73 0.40
85.1b 86.3ab 87.4ab 88.9“
6.556 6.57b 6.64ab 6.68”
506b 5556 564”b 638”
13.3” 12.6” 11.4”b 9.7b
in the same column with different superscripts
are different
(P-c 0.05).
I .78” 1.43”b I .20”b O.83b
S. Alamanou et al.
86
not in agreement with those of Lin & Zayas (1987) who found that the addition of corn germ protein in frankfurters at levels l-4% reduced the batter viscosity. This difference may be due to the lower protein content (19.4%) of corn germ protein in comparison to the high protein content (92.0%) of LSPI. The higher the protein content of batter the more water can be absorbed and the higher the viscosity. The jelly separation of batters after heating was lower (P < 0.05) at higher LSPI levels, which means that the addition of LSPI improves the water binding capacity of batter. Jelly separation was well correlated (r= -0.541, P< 0.05) with the batter viscosity (Table 7). No differences (P> 0.05) were found in fat separation between the treatments, although that with 3% LSPI had the lowest fat separation. Addition of LSPI at 3% level significantly increased the processing yield of frankfurters. No differences (P> 0.05) in processing yield were found between the control and frankfurters with 1% and 2% LSPI, but the higher the LSPI level the higher the processing yield. A correlation coefficient r= 0.503 (P< 0.05) was found between the processing yield and the protein content of frankfurters. Frankfurters with 2% and 3% LSPI had higher (PcO.05) product pH than the control. The addition of LSPI significantly decreased the purge accumulation of frankfurters during the 1st week of refrigerated (4°C) storage. Jelly and fat separation, processing yield and purge accumulation are indicative of emulsion stability which represents the ability of the meat emulsion to retain moisture and fat upon further processing (Townsend et al., 1968). The results have shown that LSPI improves the emulsion stability of batters. This may be attributed to the absorption by LSPI of the excessive water added during formulation as well as to the increase of pH. Processing yield and purge accumulation found to be significantly correlated with the batter pH (r = 0.637, P < 0.01) and product pH (r= -0.568, PC 0.05), respectively (Table 7). Wang & Zayas (1992) also found that emulsion stability of frankfurters prepared with soy protein products and corn germ protein flour was increased as pH increased from 6 to 8. Plant proteins act as proteinaceous emulsifiers which promote the formation of emulsions and help to stabilize them during processing. Their stabilising effect in emulsions is related to high electrical charge and more hydrophilic-lipophilic groups within protein structures that increase the protein-lipid and protein-water interactions (Jones, 1984; Li-Chan et al., 1984). They form a charge layer around fat droplets causing mutual repulsion, reducing interfacial tension and preventing coalescence.
Effect of LSPI Level on Instrumental LSPI level (%) Lightness L
TABLE 3 and Visual Color Evaluation of Frankfurters
Instrumental colour values Redness Yellowness a(+) b(+)
Untrained panel colour evaluationa
0
50.9
13.8bc
13.3
4.336
1 2 3
48.9 51.3 51.0
14.6b 13.3cd 11.4d
13.4 13.8 14.4
4.03bc 3.906’ 2.80’
*Evaluation scale: 6 = like extremely, 1 = dislike extremely. weans in the same column with different superscripts are different (P < 0.05).
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InfIuence of protein isolate on processing and quality of frankfurters
The effect of LSPI level on instrumental and visual colour evaluation of frankfurters is given in Table 3. No differences (P > 0.05) were found in lightness and yellowness between the treatments. The treatments with 1% and 2% LSPI level had the same (P> 0.05) redness with the control. Frankfurters with 3% LSPI had the lowest (PC 0.05) Hunter a( +) value. The results of the visual colour evaluation showed that all frankfurters with LSPI had lower colour scores than the control treatment. However the difference in colour scores between the control and the treatments with 1% and 2% LSPI were not significant. Frankfurters with 3% LSPI had the lowest (P < 0.05) visual colour score which is in accordance with the lowest (PcO.05) Hunter a( +) value. A significant correlation was found (r = 0.597, P < 0.01) between the redness of frankfurters and the visual colour evaluation scores (Table 7). The effect of LSPI level on the textural properties of frankfurters is given in Table 4. Frankfurters with 3% LSPI level had lowest (P < 0.05) fracturability, 1st bite hardness and gumminess and highest springiness. The higher the LSPI level the lower the 1st bite hardness and gumminess of frankfurters but the difference between the control and frankfurters with 1% and 2%, LSPI was not significant. LSPI level had no effect (P > 0.05) on cohesiveness and chewiness of frankfurters. The results of the LSPI level on the textural properties of frankfurters are in agreement with those of other workers. Verma et al. (1984~) also found that sausages containing chickpea flour were softer in texture as the substitution level increased. Gnanasambandam & Zayas (1992) found that frankfurters with wheat germ protein flour, soy flour and corn germ protein flour prepared with 31.5% water added during formulation had lower firmness than the control with 28% water added during formulation. According to Gnanasambandam & Zayas (1992) aroma and flavor are probably the most important attributes that influence the sensory properties of cornminuted meat products extended with non-meat protein additives. The effect of LSPI level on overall acceptability of frankfurters is given in Fig. 1. No significant differences in overall acceptability between the control and frankfurters with 1% and 2% LSPI were found, although the higher the LSPI level the lower the overall acceptability scores. Frankfurters with 3% LSPI had the lowest (PC 0.05) overall acceptability scores and were jugded by all the panelist as unacceptable. The main reason for the low acceptability scores of frankfurters with 3% LSPI level was the unpleasant and rather bitter taste and secondly the softer consistency and the light-red color. Overall acceptability of frankfurters TABLE 4
Effect of LSPI Level on Textural Properties of Frankfurters LSPI level
Fracturability (kg)
W) 0 1 2 3
7.6”
8.1” 7.4”b 5.V
1st bite hardness
2nd bite hardness
(kg)
(kg)
10.8” 8.6”6 l.O”b 4.56
1.2 5.4 5.9 4.0
Springiness
Cohesiveness
Gumminess
(%J
(kg)
(kg)
64.7b 60.1b 87.8” 86.6a
0.74 0.72 0.70 0.13
6.1” 4.8”b 5.3ab 3.2”
&Means in the same column with different superscripts are different (P < 0.05).
Chewiness
424 344 465 283
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S. Alamanou et al.
0
1
2
3
LSPI level (%) Fig. 1. Effect of LSPI level on overall acceptability of frankfurters. a: Evaluation scale: 6 = like extremely, 1 = dislike extremely. b,c: Bars with different letters are significantly different (P < 0 05).
was highly correlated (I = 0.843, P < 0.001) with visual ability (r= 0.685, P< 0.01) and well with the hardness springiness (Y= -0.607, P < 0.05) (Table 7).
color scores and fractur(r=0.596, P< 0.05) and
Effect of 1% LSPI as powder ingredient, hydrated and stabilizer in PEF on processing and quality characteristics of frankfurters The control treatment was prepared with 29% water added during formulation. All treatments with 1% LSPI were formulated with the same level of water added during formulation as the control. Although LSPI, according to the results of the previous experiment, can be used at 2% level, the 1% level was prefered because of the lower quantities of LSPI required for the experiment. No significant differences (P> 0.05) in proximate composition were found between the treatments. The moisture content ranged from 56.4 to 59.7%, the protein content from 11.8 to 12.4%, the fat content from 25.2 to 26.3% and the ash content from 2.53 to 2.60%. The effect of 1% LSPI as powder ingredient, hydrated and as stabilizer in PEF on batter characteristics, processing yield and purge accumulation is given in Table 5. Frankfurters with LSPI had higher (P < 0.05) pH value than the control. The hydration of LSPI for 20-24 h under refrigeration prior to use had a significant effect on the viscosity. The use of LSPI as hydrated and as stabilizer in PEF significantly decreased the jelly separation of batter in comparison to control. Jelly separation was significantly (r = -0.640, P < 0.01) correlated with the viscosity of batter. Frankfurters with LSPI in the form of PEF showed the lowest (P < 0.05) fat separation. The treatments with hydrated LSPI and LSPI in the PEF form had higher (PC 0.05) processing yield and lower (PC 0.05) purge accumulation than the control but not significantly different than the treatment
TABLE 5
29 29 29 29
WateP (%)
6.42’ 6.53b 6.49b 6.48’
Batter (pH)
487” 5556’ 5886 552bc
BrookJield viscosity (cp X 103)
Jelly
17.36 12.6b 6.4” 7.4c
(%)
separaI ion
0.77b 0.67’ o.sobc o.30c
Fat separation (%)
84.4’ 86.3” 87.8b 87.5b
Processing yield (%)
6.45 6.57 6.53 6.50
Finished product (PH)
2.10b 1.436” 1.23’ 1.17”
Purge accumulation (%)
Control LSPI as powder LSPI hydrated LSPPI as stabilizer LSDo.05
Treatment
47.5 48.9 48.1 49.6 3.2
15.7 15.4 16.0 15.7 2.7
12.7 13.6 12.6 14.1 1.7
Instrumental colour values Lightness L Redness a ( + ) Yellowness b ( + )
4.60 4.03 4.40 4.00 0.7
Untrained panel color evaluation
9.1 8.1 8.8 9.0 2.4
Fracturability
10.3 10.8 11.4 11.5 4.4
70.6 66.7 73.9 73.6 9.3
Textural properties 1st bite Springiness hardness (%)
0.72 0.74 0.85 0.84 0.19
Cohesiveness
Effect of 1% LSPI as Powder Ingredient, Hydrated and Stabilizer in PEF on Instrumental and Visual Color, Evaluation, Textural Properties and Overall Acceptability of Frankfurters
TABLE 6
aWater added during formulation. &=Means in the same column with different superscripts are different (P < 0 05).
Control LSPI as powder LSPI hydrated LSPI as stabilizer
Treatment
Effect of 1% LSPI as Powder Ingredient, Hydrated and Stabilizer in PEF on Batter Characteristics, Processing Yield and Purge Accumulation
90
S. Alamanou et al.
with LSPI as powder ingredient. Processing yield was significantly correlated with the batter viscosity (r = 0.628, P < 0.01) and purge accumulation with the product pH (r= -0.733, P < 0.001) (Table 7). The significant effect of hydration and preemulsification of LSPI on processing yield is probably due to the better hydration of batter during the 20-24 h refrigerated (4°C) storage prior to use. Lecomte et al. (1993) have also found that the use of soy protein products as stabilizers in PEF had a significant effect on processing yield of frankfurters. The mode of use of 1% LSPI in the preparation of frankfurters had no effect on the colour and texture. No differences (P > 0.05) were found in lightness, redness, yellowness and visual colour scores, as well as in textural properties, of frankfurters between the treatments (Table 6). Lecomte et al. (1993) found that the use of soy protein products as powder ingredients, and as stabilizer in PEF had no effect on the colour of frankfurters. Also, Lin & Zayas (1987) did not found significant differences in colour, hardness and cooking losses between the control and frankfurters prepared with corn germ protein as stabilizer in PEF The effect of the methods of using 1% LSPI in the preparation of frankfurters on overall acceptability is given in Fig. 2. Frankfurters to hydrated LSPI and LSPI in PEF form had a similar (P> 0.05) overall acceptability to the control and higher (P < 0.05) than the frankfurters with LSPI as powder ingredient. The better hydration of batter in these two treatments may result in the dilution of substances which are responsible for off-flavors and undesireable taste when LSPI is used at high concentrations. Lecomte et al. (1993) found that the incorporation of soy proteins as a pre-emulsified fat decreased the specific soy bean and bitter 4.0 T
b
4.6 --
b
cu 5 4.4 -.n co & g 4.2 -lu = 2 d
4--
+
+
3.6 -r Control
LSPI as powder
+ LSPI hydrated
LSPI 88 stabilizer
Treatments Fig. 2. Effect of 1% LSPI level on overall acceptability of frankfurters. a: Evaluation scale: 6 = like extremely, 1 = dislike extremely. b,c: Bars with different letters are different (P < 0.05).
l
l
l
-0.541’
** (P<:O.OOl), * (P
Protein content Batter pH Viscosity Product pH Lightness L Redness a( + ) Visual color Fracturability 1st bite hardness Springiness-0.607’
0.503’ 0.637”
Processing yield
(P
Jelly separation
-0.568’
Experiment A Purge accumulation
0.597”
Visual colour
0.843”’ 0.685” 0.596’
Overall acceptability
-0.640”
Jelly separation
Variables
0.531’ 0.628”
Processing yield
TABLE 7 Correlation Coefficient Values Between Selected Response
-0.733”’
Experiment B Purge accumulation
-0.647”
Visual colour
0.781”’
Overall acceptability
iF; 9’ E;. %
n; 0 2 a
92
S. Alamanou
et al.
notes from frankfurters. They attributed this finding to the masking effect of pre-emulsification as a result of the encapsulation of soy proteins and physical covering of flavor components contributing to beany and bitter attributes. Overall acceptability was also found to be significantly correlated (r = 0.78 1, P < 0.001) with the visual colour scores of frankfurters (Table 7).
CONCLUSIONS LSPI can be used as an additive in comminuted meat products at levels up to 2%. It improves the processing yield, reduces the purge accumulation in the packaged product during the refrigerated storage and does not affect, negatively, the colour, the texture and the sensory characteristics of the finished product. However, it cannot be used at higher levels because, although it increases significantly the processing yield and reduces the purge accumulation it affects negatively the overall acceptability of the product due to an unpleasant and rather bitter taste. The hydration of 1% LSPI for 2&24 h prior to use as well as the utilization of LSPI as a stabilizer in PEF, prepared 20-24 h prior to use, have a beneficial effect on the processing and sensory characteristics of frankfurters.
REFERENCES Alamanou, S. & Doxastakis, G. (1995). Food Hydrocoll., 9, 103. AOAC (1984). Ojicial Methods of Analysis (14th edn). Association
of Official Analytical Chemists, Washington, DC, USA. Bloukas, J. G. & Honikel, K. 0. (1992). Meat Sci., 32, 31. Bourne, M. C. (1978). Food Technol., 32, 62. Cerletti, P. & Duranti, M. (1979). JAOCS, 56, 460. Christie, W. W. (1982). Lipid Analysis. Pergamon Press, Oxford, UK, pp. 22-23. Cruz, 0. A. & Hedrick, H. B. (1985). J. Food Sci., 50, 1177. Gnanasambandam, R. & Zayas, J. F. (1992). J. Food Sci., 57, 829. Gross, U., Galindo, R. G. & Schoeneberger, H. (1983). Qual. Plant Foods Hum. Nutr., 32, 155. Jones, K. W. (1984). Proc. Recip. Meat Cont., 37, 52. Kinsella, J.E. (1979). JAOCS, 56, 242. Kinsella, J. E. & Damodaran, S. (1980). In Analysis and Control of Less Desirable Flavors in Food and Beverage. Academic Press, New York, USA, p. 95. Lecomte, N. B., Zayas, J. F. & Kastner, C. L. (1993). J. Food Sci., 58, 464. Leonard, P., Ruiz, Jr & Hove, E. I. (1976). J. Sci. Food Agric., 27, 667. Li-Chan, E., Nakai, S. & Wood, D. F. (1984). J. Food Sci., 49, 345. Lin, M. J. Y., Humbert, E. S. & Sosulski, F. W. (1975). J. Inst. Can. Sci. Technol. Aliment., S(2), 97. Lin, C. S. & Zayas, J. F. (1987). J. Food Sci., 52, 545. Mittal, G. S. & Usborne, W. R. (1985). Food TechnoI., 39, (4), 121. MSTAT (1985). Michigan State University. East Lansing, MI, USA. Padua, M. R. (1983). J. Food Sci., 48, 1145. Schmidt, G. R., Mawson, R. F. & Siegel, D. G. (1981). Food Technol., 35 (5), 235. Townsend, W. E., Witnauer, L P., Rillof, J. A. & Swift, C. E. (1968). Food Technol., 32(7), 62. Verma, M. M., Ledward, D. A. & Lawrie, R. A. (1984a). Meat Sci., 11, 109.
Infuence of protein isolate on processing and quality of frankfurters
Verma, M. M., Ledward, D. A. & Lawrie, R. A. (1984b). Meat Sci., 11, 171. Wang, C. R. & Zayas, J. F. (1992). J. Food Sci., 57, 726. Williams, C. W. & Zabik, M. E. (1975). J. Food Sci., 40, 502. Willing, M. D. (1974). JAOCS, 51, 128A. Wills, R. B. H. & Kabirullah, M. (1981). J. Food Sci., 46, 1657. Young, V. R., Scrimshaw, N. S., Torun, B. & Viteri, F. (1979). JAOCS, 56, 110. Zayas, J. F. & Lin, C. S. (1988). J. Food Sci., 53, 1587.
93
0309-1740(95)00013-5
influence of Protein Isolate from Lupin Seeds (Lupinus albus ssp. Graecus) on Processing and Quality Characteristics of Frankfurters Silvana Alamanou,
a * J. G. Bloukas,b dz G. Doxastakis”
E. D. Panera
“Laboratory of Food Chemistry and Technology, Faculty of Chemistry, Aristotle University of Thessaloniki, GR 540 06, Thessaloniki, Greece bLaboratory of Food Science and Technology, Faculty of Agriculture, Aristotle University of Thessaloniki, GR 540 06, Thessaloniki, Greece (Received 15 September 1994; revised version received 26 November accepted 15 February 1995)
1994;
ABSTRACT Lupin protein isolate (92% protein) from seeds of Lupinus albus ssp. Graecus (LSPI) was used as powder ingredient for the manufacture offrankfurters at levels 0, 1, 2 and 3% of the formulation weight. Additional 1% water was added during batter formulation to each 1% protein used. LSPI increased (P < 0.05) the pH and viscosity of batter and reduced the jelly separation. Increasing the LSPI level resulted in higher (P < 0.05) processing yield and lower (P < 0.05) purge accumulation, redness and visual colour scores and hardness of frankfurters. Signtjicant differences in overall acceptability were not found among the control and frankfurters with 1% and 2% LSPI. Frankfurters with 3% LSPI were judged as unacceptable. Incorporation of LSPI at 1% level either in hydrated form or as stabilizer in pre-emulsified fat improved the processing characteristics and overall acceptability of frankfurters made with LSPI as powder ingredient and did not affect the color and texture.
INTRODUCTION The manufacture of cornminuted meat products is dependent upon the formation of a functional protein matrix within these products (Schmidt et al., 1981). Meat proteins are well recognized for their functional properties in formation and stabilization of the matrix. The relevant functional properties include the emulsifying capacity, emulsion stability, water binding, gelation and cohesion of particles. These functional properties are interrelated and are determined by the quantity, composition, conformation and physical properties of the muscle proteins present in the cornminuted meat product (Mittal & Usborne, 1985). However, the increasing cost of animal protein and the fact that the availability of meat is *Author to whom correspondence
should be addressed. 79
80
S. Alamanou et al.
scarce in some countries have urged researchers to explore the possibilities of utilizing different types of unconventional protein sources in comminuted meat products in order to reduce the formulation cost. Plant proteins have the advantage that they can be produced in large quantities and have low cost. The suitability of plant proteins for the production of comminuted meat products is related to such functional properties as water retention, fat-binding, emulsifying capacity, sensory properties, storage stability and nutritional quality of finished product. Soy proteins have received most attention because of their availability, low price, nutritional value (Young et al., 1979) and unique functional properties. Soy proteins have the ability to enhance and stabilize fat emulsion, improve viscosity, impart texture upon gelation following cooking, and improve moisture retention and overall yields. The ability of soy proteins to bind and retain meat juices enhances mouthfeel and flavor in meat emulsions (Kinsella, 1979). However, soy products often have a characteristic off-flavor, which has been described as ‘beany’ or ‘cereal-like’ and a bitter and astringent off-aroma (Kinsella & Damodaran, 1980; Williams & Zabik, 1975). To minimize the soy flavor, spices and seasonings should be added to the hydration water and allowed the hydrated mixture to stand at low temperature for flavor penetration into soy, rather than the meat (Willing, 1974). Lecomte et al. (1993) found that the incorporation of soy proteins, in formulations of frankfurters as pre-emulsified fat, resulted in a reduction of specific soyabean off-flavor and off-aroma. Sunflower offers excellent potential as a plant protein source due to its high protein content and to the fact that it ranks as the second major oilseed crop in the world. Lin et al. (1975) found that the addition of sunflower products (flour and protein concentrates) to wieners provided better emulsion stability than did the soy supplements. Wills & Kabirullah (1981) prepared beef sausages with the addition of sunflower flour and resulted in a product which was equally acceptable to the taste panel to the sausages prepared with gluten and soy protein isolate. However, sausages prepared with sunflower protein isolate were the least acceptable due to a dark coloration. Padua (1983) investigated the effect on acceptability of replacing 0, 20, 30 and 40% meat in loaves with hydrated textured defatted sesame flour. The loaves with 30% meat replaced by the defatted sesame flour were scored higher than the rest of the loaves, even higher than all-meat loaves. Cruz & Hedrick (1985) prepared fermented salami containing 0, 9, 18 and .27% defatted sesame flour and found that it can be used at either 9 or 18% level without detrimental effect upon sensory attributes of the product. Fresh skinless sausages were prepared by Verma et al. (1984~) in which some of the meat was replaced on a protein-to-protein basis by chickpea flour. The results showed that levels of substitution up to 30% protein replacement could be made without adversely affecting product acceptability. Later work, however, showed that it was necessary to heat chickpea flour to 80°C for 1 h to prevent discoloration of raw sausages caused by lipid peroxidation on storage (Verma et al., 1984b). Lin & Zayas (1987) incorporated corn germ protein in comminuted meat products as an ingredient (4%) and as stabilizer (2%) in pre-emulsified fat (PEF). They found that corn germ protein could be used as an ingredient at 3.5% and as stabilizer at 2% in PEF to increase yield while maintaining textural and other qualities similar to those of the whole meat product. In another work Zayas & Lin (1988) developed a process for incorporation of defatted corn germ protein in
Influence of protein isolate on processing and quality of frankfurters
81
frankfurters. They found that using it at 3% level resulted in an improvement of the quality characteristics and increased the yield of the product. Finaly, Gnanasambandam & Zayas (1992) compared the functionality of wheat germ protein in frankfurters as compared with corn germ and soy proteins. They found that wheat germ protein flour is a potential non-meat protein additive that can be utilized as an extender in comminuted meat products. At the 3.5% level it affected in the same way the quality characteristics of frankfurters as soy flour and corn germ protein flour. Lupin is a very well known legume in Europe, especially in Mediterranean countries, in South America (Chile and Peru), as well as in Australia and New Zealand, where it was cultivated for centuries. The great advantage of the seed is the elevated protein content which ranges between 31% and 42% in the different lupin species. This high protein concentration is sometimes superior to that of soy and moreover lupin protein amino acid pattern is comparable to that of soy (Cerletti & Duranti, 1979). Gross et al. (1983) found that lupin based dishes, derived from Lupinus mutabilis cultivated in Peru, have been well accepted according to a test of acceptability performed with children from 8 to 15 years of age over a 3-year period. No research has been conducted using the lupin protein isolate as an additive in comminuted meat products. The object of this study was (a) to evaluate the lupin protein isolate from seeds of Lupinus albus ssp. Graecus, as a potential non-meat protein additive that can be utilized as an extender in comminuted meat products, and (b) to establish its influence, as powder ingredient, hydrated or as a stabilizer in pre-emulsified fat on processing and quality characteristics of frankfurters.
MATERIALS
AND
METHODS
Meat source Frozen lean beef, lean fresh pork and fresh pork backfat were obtained from a local meat market. Partially thawed beef and fresh pork were trimmed of separable fat to provide extra lean meats. The lean meat and the pork backfat were separately ground through a 12 mm plate and then through a 3 mm plate. The ground meats and pork backfat were vacuum packaged in moisture-proof plastic bags and frozen at -20°C for l-2 weeks until product formulation. Representative samples were analyzed for moisture, fat and protein (AOAC, 1984) prior to freezing. All raw materials were tempered at 0°C for 24 h prior to use. Lupin seed protein isolate Lupin seeds (Lupinus albus ssp. Graecus) were provided from Lasithi, Crete, Greece. The dry seeds were ground in a Tomas-Wiley mill (model ED-5 USA) to pass a 100 mesh screen. In this way the protein extraction from the flour may exceed 96% during the solubilisation by the alkali (Leonard et al., 1976). The flour was then defatted with n-hexane (1:3 w/v), by the Soxhlet method, at a temperature of about 40°C until the fat content was reduced to about 5% (Christie, 1982). The solvent residues were then removed by drying the flour at room temperature.
a2
S. Alamanou et al.
The defatted flour was mixed with distilled water (1: 10 w/v) and the suspension adjusted to pH 9.0 with alkali (1N NaOH) in order to extract the proteins. The slurry was stirred for 30 min at 20°C. After that the insoluble residue (water insoluble polysaccharides plus residual protein) is separated by filtering and centrifuging at 5 000 g for 20 min. The residue was mixed with distilled water (1:5 w/v) and re-extracted under the same conditions. The supernatants were precipitated at pH 4.5 with food grade acid (1N HCI) and centrifuged at 5000 g for 20 min. The precipitate was adjusted to pH 7.0 for neutral protein isolate and freeze-dried (Alamanou & Doxastakis, 1994). The mean composition of lupin seed protein isolate (LSPI) used was 92.0% protein, 5.4% moisture, 0.5% fat and 2.1% ash. Experiment a
In this experiment the lupin seed protein isolate (LSPI) was used as a powder ingredient for the manufacture of frankfurters at four levels: 0, 1,2 and 3 % of the formulation weight. The control treatment (0% LSPI) was formulated so that the amount of added water to be 28%of batter and the composition of final product aproximately 11% protein and 27% fat. All other treatments were formulated by the addition of 1% extra water to every 1% protein used (Lin & Zayas, 1987; Gnanasambandam & Zayas, 1992). Experiment b
In this experiment lupin seed protein isolate (LSPI) was used at 1% level as powder ingredient, hydrated and as stabilizer in pre-emulsified fat (PEF) in comparison to the control treatment (0% LSPI) as in previous experiment. The treatments with LSPI were formulated by the addition of 1% extra water to every 1% protein used. The hydration of LSPI was done by mixing with four parts of water (ratio 1:4) and the slurry was kept in a cooler at + 4°C for 20-24 h prior to use. The PEF sample was made following the procedure of Lecomte et al. (1993). The mixture of LSPI (1% of the formulation weight) and water (half the added water of the formulation) was blended in a Braun blender at high speed for 2 min. The protein slurry was incubated for 30 min in a water bath at 80°C. Pork backfat was softened and partially melted by warming in a water bath with boiling water and immediately was added slowly and emulsified in the blender with the protein slurry at high speed for 5 min. The PEF was kept in a cooler at + 4°C for 24 h prior to use. Frankfurter manufacture
The partially thawed meat was chopped for 2-3 s in a Laska 30 L cutter at low speed and then mixed with the following ingredients, expressed as percentage of the batter weight: 1.7% salt, 0.02% sodium nitrite, 0.3% polyphosphates and 0.75% seasoning. The mixed meat was dry chopped for 2&30 s, 0.08% sodium ascorbate was added, diluted in water, and the chopping continued with the addition of one-third of total added water (ice chips) until a temperature of + 3°C was reached. At this point the LSPI as powder, hydrated or as stabilizer in PEF, where needed, was mixed with the chopped meat together with the remainder ice/
Influence of protein isolate on processing and quality of frankfurters
83
water and the thawed pork backfat and the batter was chopped at high speed until the final temperature reached 12°C. Immediately after chopping the batter of each treatment was vacuum-stuffed into 24 mm diameter Nojax cellulose casings. Each treatment was handlinked at 15 cm intervals and the frankfurters were heat processed and smoked in a smoke house to internal temperature 72°C for 5 min. The frankfurters were showered for 15 min and chilled at + 2°C for 24 h. After chilling, the frankfurters were handpeeled, vacuum packaged (vacuum level 650 mm Hg) in film pouches with a reported oxygen permeability rate of 116 cm3/m2/24 h/l atm (23°C 0% RH) and stored in the dark in a cooler at + 4°C until subsequent analysis. Chemical analysis
Representative samples from each treatment were homogenized and analyzed, prior to vacuum packaging, for percentage moisture, fat (ether-extractable), protein and ash according to standard AOAC (1984) procedure. All analyses were performed in duplicate. pH measurement
pH was determined with a WTW digital pH meter in a slurry made by blending 20 g batter or final product with 80 ml distilled water in a Braun mixer for 1 min at high speed. Data are means of two measurements. Batter viscosity
Viscosity was measured after keeping the batter for 4-5 h in a and tempering for 1 h to ambient temperature. The measurement a Brookfield digital viscometer, model DV-II, set at 2.5 rpm and spindle No. 5. The readings were noted after 30 s shearing time centipoises. Data are means of the first five readings on a 100 with batter.
cooler at +2”C was made with equipped with a and recorded in ml beaker filled
Jelly and fat separation
The jelly and fat separation was measured by the procedure described by Bloukas & Honikel (1992). At the end of the comminution process three preweighed cans (size 58 x 73 mm) were filled with batter. The cans were closed and heated for 35 min in a boiling water bath (core temperature about 9O’C). After cooling in running tap water the cans were stored at 4°C for 24 h. After warming up the cans in a water bath at 45°C for 1 h they were opened and the fluid of each can was collected in a 100 ml volumetric cylinder. The fluid jelly and fat, separated in the volumetric cylinder, was measured in ml and calculated as a percent of the original weight of batter. The mean value of three cans was taken for each treatment. Processing yield
Frankfurters were weighed before heat processing and smoking and after chilling at + 2°C for 24 h. The processing yield (%) was determined from their weights.
84
S. Alamanou et al.
Purge accumulation Two vacuum-packages (about 25&300 g each) per treatment were used to determine purge accumulation of frankfurters the 1st week of storage at 4°C. Before packaging each link of frankfurters was dried with paper tissue and all links per package were weighed. After removing sausages from the package each link was again dried with paper tissue and all links per package were reweighed. Purge accumulation was determined from the difference in weights between the two measurements expressed as percentage of initial weight. Colour measurement Colour measurements were performed on the 1st week of refrigerated (4°C) storage. A Trucolour Neotec calorimeter was used to measure the colour numbers L, a and b (Hunter color system) at the skin of frankfurters. The instrument was standardized using a white ceramic tile calibrated to tristimulus values of L= + 96.0, a = - 1.03 and b = + 2.4. Two frankfurters per treatment were used. Four measurements were taken per link and data are means of eight measurements. Texture profile analysis An Instron Universal Testing Machine, model 1125, was used to conduct texture profile analysis, as described by Bourne (1978), the 1st week of refrigerated (4°C) storage. Samples were prepared by steeping frankfurters in boiling water for 2 min and cooling to ambient temperature. Four 20 mm long sections per treatment were axially compressed by a two cycle compression test to 75% of original height. Force-time deformation curves were recorded at a crosshead speed 5 cm/ min, chart speed 5 cm/min and full-scale 50 kg. Texture variables of force and area measurements were: FF = force to fracture; Fi = maximum force for first compression; F2 = maximum force for second compression; Ai = total energy for first compression; AZ = total energy for second compression; cohesiveness = AZ/ Ai; and gumminess = FixAz/Ai. Springiness (S) was calculated as the percentage of initial height recovered after the first compression, and chewiness = F1xA2/AlxS. Peak areas were determined by using the Ladd Graphic Data Analyzing System. Sensory evaluation A 15-member untrained panel evaluated frankfurters during the 1st week of storage for colour and overall acceptability on a 6-point hedonic scale (6=like extremely, 1 = dislike extremely). Panel members were selected from students, staff and faculty of the Laboratory of Chemistry and Technology. Colour acceptability was evaluated during display of two links from each treatment. Samples for overall acceptability were prepared by steeping frankfurters in boiling water in individual pans for 2 min. Warm 2.5 cm long pieces from each treatment were randomly distributed for evaluation. The panelists were instructed to evaluate the appearance, the texture, the flavor and the juiciness of the products and express their overall acceptability.
85
Infuence of protein isolate on processing and quality of frankfurters
Statistical
analysis
All paraStatistical analysis was performed using the MSTAT _. -. (1985) program. _ __ _. _ meters studled were analyzed by one-way analysis of variance. Means were compared by using the LSDo,oS test. Simple correlations were determined between selected response variables.
RESULTS
AND
DISCUSSION
Effect of LSPI level on processing and quality characteristics
of frankfurters
The approximate composition of frankfurters, as affected by the LSPI level, is given in Table 1. The higher the LSPI level the higher (P < 0.05) the protein and moisture content of frankfurters. The mean protein content of frankfurters with LSPI was lower than the targeted values. The control treatment had higher (P < 0.05) fat content and lower (P < 0.05) ash content than the treatments with LSPI. No differences (P > 0.05) in fat and ash content were found between the treatments with LSPI. The effect of LSPI level on batter characteristics, processing yield and purge accumulation is given in Table 2. The addition of LSPI increased the pH and the viscosity of the batters. The treatment with 3% LSPI had a significantly higher (P < 0.05) batter pH and viscosity than the control treatment. These results are TABLE 1 Effect of LSPI Level on Approximate Composition LSPI
level
(%)
0 1 2 3
Watelm
(%)
Moisture
28 29 30 31
(%)
Protein
56.5’ 57.2bc 57.46’ 58.0b
of Frankfurters (%)
Ash (%)
Fat (%)
29.gb 28.3” 27.4” 25.9”
11.3e 11.8d 12.6’ 13.56
2.3’ 2.5b 2.5b 2.5b
OWater added during formulation. Control treatment formulated for 28% added 1% water was added with every 1% protein addition. &‘Means in the same column with different superscripts are different (P < 0.05). TABLE 2 Effect of LSPI Level on Batter Characteristics, Processing LSPI level
Batter (PH)
ml 0 1 2 3
“bMeans
6.47b 6.53”b 6.6OOb 6.68”
water;
Yield and Purge Accumulation
Brookfield viscosity
Jelly separation
Fat separation
Processing yield
Finished product
Purge accumulation
(CP x I@)
I%)
(%)
(%)
(PH)
(%)
0.57 0.67 0.73 0.40
85.1b 86.3ab 87.4ab 88.9“
6.556 6.57b 6.64ab 6.68”
506b 5556 564”b 638”
13.3” 12.6” 11.4”b 9.7b
in the same column with different superscripts
are different
(P-c 0.05).
I .78” 1.43”b I .20”b O.83b
S. Alamanou et al.
86
not in agreement with those of Lin & Zayas (1987) who found that the addition of corn germ protein in frankfurters at levels l-4% reduced the batter viscosity. This difference may be due to the lower protein content (19.4%) of corn germ protein in comparison to the high protein content (92.0%) of LSPI. The higher the protein content of batter the more water can be absorbed and the higher the viscosity. The jelly separation of batters after heating was lower (P < 0.05) at higher LSPI levels, which means that the addition of LSPI improves the water binding capacity of batter. Jelly separation was well correlated (r= -0.541, P< 0.05) with the batter viscosity (Table 7). No differences (P> 0.05) were found in fat separation between the treatments, although that with 3% LSPI had the lowest fat separation. Addition of LSPI at 3% level significantly increased the processing yield of frankfurters. No differences (P> 0.05) in processing yield were found between the control and frankfurters with 1% and 2% LSPI, but the higher the LSPI level the higher the processing yield. A correlation coefficient r= 0.503 (P< 0.05) was found between the processing yield and the protein content of frankfurters. Frankfurters with 2% and 3% LSPI had higher (PcO.05) product pH than the control. The addition of LSPI significantly decreased the purge accumulation of frankfurters during the 1st week of refrigerated (4°C) storage. Jelly and fat separation, processing yield and purge accumulation are indicative of emulsion stability which represents the ability of the meat emulsion to retain moisture and fat upon further processing (Townsend et al., 1968). The results have shown that LSPI improves the emulsion stability of batters. This may be attributed to the absorption by LSPI of the excessive water added during formulation as well as to the increase of pH. Processing yield and purge accumulation found to be significantly correlated with the batter pH (r = 0.637, P < 0.01) and product pH (r= -0.568, PC 0.05), respectively (Table 7). Wang & Zayas (1992) also found that emulsion stability of frankfurters prepared with soy protein products and corn germ protein flour was increased as pH increased from 6 to 8. Plant proteins act as proteinaceous emulsifiers which promote the formation of emulsions and help to stabilize them during processing. Their stabilising effect in emulsions is related to high electrical charge and more hydrophilic-lipophilic groups within protein structures that increase the protein-lipid and protein-water interactions (Jones, 1984; Li-Chan et al., 1984). They form a charge layer around fat droplets causing mutual repulsion, reducing interfacial tension and preventing coalescence.
Effect of LSPI Level on Instrumental LSPI level (%) Lightness L
TABLE 3 and Visual Color Evaluation of Frankfurters
Instrumental colour values Redness Yellowness a(+) b(+)
Untrained panel colour evaluationa
0
50.9
13.8bc
13.3
4.336
1 2 3
48.9 51.3 51.0
14.6b 13.3cd 11.4d
13.4 13.8 14.4
4.03bc 3.906’ 2.80’
*Evaluation scale: 6 = like extremely, 1 = dislike extremely. weans in the same column with different superscripts are different (P < 0.05).
87
InfIuence of protein isolate on processing and quality of frankfurters
The effect of LSPI level on instrumental and visual colour evaluation of frankfurters is given in Table 3. No differences (P > 0.05) were found in lightness and yellowness between the treatments. The treatments with 1% and 2% LSPI level had the same (P> 0.05) redness with the control. Frankfurters with 3% LSPI had the lowest (PC 0.05) Hunter a( +) value. The results of the visual colour evaluation showed that all frankfurters with LSPI had lower colour scores than the control treatment. However the difference in colour scores between the control and the treatments with 1% and 2% LSPI were not significant. Frankfurters with 3% LSPI had the lowest (P < 0.05) visual colour score which is in accordance with the lowest (PcO.05) Hunter a( +) value. A significant correlation was found (r = 0.597, P < 0.01) between the redness of frankfurters and the visual colour evaluation scores (Table 7). The effect of LSPI level on the textural properties of frankfurters is given in Table 4. Frankfurters with 3% LSPI level had lowest (P < 0.05) fracturability, 1st bite hardness and gumminess and highest springiness. The higher the LSPI level the lower the 1st bite hardness and gumminess of frankfurters but the difference between the control and frankfurters with 1% and 2%, LSPI was not significant. LSPI level had no effect (P > 0.05) on cohesiveness and chewiness of frankfurters. The results of the LSPI level on the textural properties of frankfurters are in agreement with those of other workers. Verma et al. (1984~) also found that sausages containing chickpea flour were softer in texture as the substitution level increased. Gnanasambandam & Zayas (1992) found that frankfurters with wheat germ protein flour, soy flour and corn germ protein flour prepared with 31.5% water added during formulation had lower firmness than the control with 28% water added during formulation. According to Gnanasambandam & Zayas (1992) aroma and flavor are probably the most important attributes that influence the sensory properties of cornminuted meat products extended with non-meat protein additives. The effect of LSPI level on overall acceptability of frankfurters is given in Fig. 1. No significant differences in overall acceptability between the control and frankfurters with 1% and 2% LSPI were found, although the higher the LSPI level the lower the overall acceptability scores. Frankfurters with 3% LSPI had the lowest (PC 0.05) overall acceptability scores and were jugded by all the panelist as unacceptable. The main reason for the low acceptability scores of frankfurters with 3% LSPI level was the unpleasant and rather bitter taste and secondly the softer consistency and the light-red color. Overall acceptability of frankfurters TABLE 4
Effect of LSPI Level on Textural Properties of Frankfurters LSPI level
Fracturability (kg)
W) 0 1 2 3
7.6”
8.1” 7.4”b 5.V
1st bite hardness
2nd bite hardness
(kg)
(kg)
10.8” 8.6”6 l.O”b 4.56
1.2 5.4 5.9 4.0
Springiness
Cohesiveness
Gumminess
(%J
(kg)
(kg)
64.7b 60.1b 87.8” 86.6a
0.74 0.72 0.70 0.13
6.1” 4.8”b 5.3ab 3.2”
&Means in the same column with different superscripts are different (P < 0.05).
Chewiness
424 344 465 283
88
S. Alamanou et al.
0
1
2
3
LSPI level (%) Fig. 1. Effect of LSPI level on overall acceptability of frankfurters. a: Evaluation scale: 6 = like extremely, 1 = dislike extremely. b,c: Bars with different letters are significantly different (P < 0 05).
was highly correlated (I = 0.843, P < 0.001) with visual ability (r= 0.685, P< 0.01) and well with the hardness springiness (Y= -0.607, P < 0.05) (Table 7).
color scores and fractur(r=0.596, P< 0.05) and
Effect of 1% LSPI as powder ingredient, hydrated and stabilizer in PEF on processing and quality characteristics of frankfurters The control treatment was prepared with 29% water added during formulation. All treatments with 1% LSPI were formulated with the same level of water added during formulation as the control. Although LSPI, according to the results of the previous experiment, can be used at 2% level, the 1% level was prefered because of the lower quantities of LSPI required for the experiment. No significant differences (P> 0.05) in proximate composition were found between the treatments. The moisture content ranged from 56.4 to 59.7%, the protein content from 11.8 to 12.4%, the fat content from 25.2 to 26.3% and the ash content from 2.53 to 2.60%. The effect of 1% LSPI as powder ingredient, hydrated and as stabilizer in PEF on batter characteristics, processing yield and purge accumulation is given in Table 5. Frankfurters with LSPI had higher (P < 0.05) pH value than the control. The hydration of LSPI for 20-24 h under refrigeration prior to use had a significant effect on the viscosity. The use of LSPI as hydrated and as stabilizer in PEF significantly decreased the jelly separation of batter in comparison to control. Jelly separation was significantly (r = -0.640, P < 0.01) correlated with the viscosity of batter. Frankfurters with LSPI in the form of PEF showed the lowest (P < 0.05) fat separation. The treatments with hydrated LSPI and LSPI in the PEF form had higher (PC 0.05) processing yield and lower (PC 0.05) purge accumulation than the control but not significantly different than the treatment
TABLE 5
29 29 29 29
WateP (%)
6.42’ 6.53b 6.49b 6.48’
Batter (pH)
487” 5556’ 5886 552bc
BrookJield viscosity (cp X 103)
Jelly
17.36 12.6b 6.4” 7.4c
(%)
separaI ion
0.77b 0.67’ o.sobc o.30c
Fat separation (%)
84.4’ 86.3” 87.8b 87.5b
Processing yield (%)
6.45 6.57 6.53 6.50
Finished product (PH)
2.10b 1.436” 1.23’ 1.17”
Purge accumulation (%)
Control LSPI as powder LSPI hydrated LSPPI as stabilizer LSDo.05
Treatment
47.5 48.9 48.1 49.6 3.2
15.7 15.4 16.0 15.7 2.7
12.7 13.6 12.6 14.1 1.7
Instrumental colour values Lightness L Redness a ( + ) Yellowness b ( + )
4.60 4.03 4.40 4.00 0.7
Untrained panel color evaluation
9.1 8.1 8.8 9.0 2.4
Fracturability
10.3 10.8 11.4 11.5 4.4
70.6 66.7 73.9 73.6 9.3
Textural properties 1st bite Springiness hardness (%)
0.72 0.74 0.85 0.84 0.19
Cohesiveness
Effect of 1% LSPI as Powder Ingredient, Hydrated and Stabilizer in PEF on Instrumental and Visual Color, Evaluation, Textural Properties and Overall Acceptability of Frankfurters
TABLE 6
aWater added during formulation. &=Means in the same column with different superscripts are different (P < 0 05).
Control LSPI as powder LSPI hydrated LSPI as stabilizer
Treatment
Effect of 1% LSPI as Powder Ingredient, Hydrated and Stabilizer in PEF on Batter Characteristics, Processing Yield and Purge Accumulation
90
S. Alamanou et al.
with LSPI as powder ingredient. Processing yield was significantly correlated with the batter viscosity (r = 0.628, P < 0.01) and purge accumulation with the product pH (r= -0.733, P < 0.001) (Table 7). The significant effect of hydration and preemulsification of LSPI on processing yield is probably due to the better hydration of batter during the 20-24 h refrigerated (4°C) storage prior to use. Lecomte et al. (1993) have also found that the use of soy protein products as stabilizers in PEF had a significant effect on processing yield of frankfurters. The mode of use of 1% LSPI in the preparation of frankfurters had no effect on the colour and texture. No differences (P > 0.05) were found in lightness, redness, yellowness and visual colour scores, as well as in textural properties, of frankfurters between the treatments (Table 6). Lecomte et al. (1993) found that the use of soy protein products as powder ingredients, and as stabilizer in PEF had no effect on the colour of frankfurters. Also, Lin & Zayas (1987) did not found significant differences in colour, hardness and cooking losses between the control and frankfurters prepared with corn germ protein as stabilizer in PEF The effect of the methods of using 1% LSPI in the preparation of frankfurters on overall acceptability is given in Fig. 2. Frankfurters to hydrated LSPI and LSPI in PEF form had a similar (P> 0.05) overall acceptability to the control and higher (P < 0.05) than the frankfurters with LSPI as powder ingredient. The better hydration of batter in these two treatments may result in the dilution of substances which are responsible for off-flavors and undesireable taste when LSPI is used at high concentrations. Lecomte et al. (1993) found that the incorporation of soy proteins as a pre-emulsified fat decreased the specific soy bean and bitter 4.0 T
b
4.6 --
b
cu 5 4.4 -.n co & g 4.2 -lu = 2 d
4--
+
+
3.6 -r Control
LSPI as powder
+ LSPI hydrated
LSPI 88 stabilizer
Treatments Fig. 2. Effect of 1% LSPI level on overall acceptability of frankfurters. a: Evaluation scale: 6 = like extremely, 1 = dislike extremely. b,c: Bars with different letters are different (P < 0.05).
l
l
l
-0.541’
** (P<:O.OOl), * (P
Protein content Batter pH Viscosity Product pH Lightness L Redness a( + ) Visual color Fracturability 1st bite hardness Springiness-0.607’
0.503’ 0.637”
Processing yield
(P
Jelly separation
-0.568’
Experiment A Purge accumulation
0.597”
Visual colour
0.843”’ 0.685” 0.596’
Overall acceptability
-0.640”
Jelly separation
Variables
0.531’ 0.628”
Processing yield
TABLE 7 Correlation Coefficient Values Between Selected Response
-0.733”’
Experiment B Purge accumulation
-0.647”
Visual colour
0.781”’
Overall acceptability
iF; 9’ E;. %
n; 0 2 a
92
S. Alamanou
et al.
notes from frankfurters. They attributed this finding to the masking effect of pre-emulsification as a result of the encapsulation of soy proteins and physical covering of flavor components contributing to beany and bitter attributes. Overall acceptability was also found to be significantly correlated (r = 0.78 1, P < 0.001) with the visual colour scores of frankfurters (Table 7).
CONCLUSIONS LSPI can be used as an additive in comminuted meat products at levels up to 2%. It improves the processing yield, reduces the purge accumulation in the packaged product during the refrigerated storage and does not affect, negatively, the colour, the texture and the sensory characteristics of the finished product. However, it cannot be used at higher levels because, although it increases significantly the processing yield and reduces the purge accumulation it affects negatively the overall acceptability of the product due to an unpleasant and rather bitter taste. The hydration of 1% LSPI for 2&24 h prior to use as well as the utilization of LSPI as a stabilizer in PEF, prepared 20-24 h prior to use, have a beneficial effect on the processing and sensory characteristics of frankfurters.
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of Official Analytical Chemists, Washington, DC, USA. Bloukas, J. G. & Honikel, K. 0. (1992). Meat Sci., 32, 31. Bourne, M. C. (1978). Food Technol., 32, 62. Cerletti, P. & Duranti, M. (1979). JAOCS, 56, 460. Christie, W. W. (1982). Lipid Analysis. Pergamon Press, Oxford, UK, pp. 22-23. Cruz, 0. A. & Hedrick, H. B. (1985). J. Food Sci., 50, 1177. Gnanasambandam, R. & Zayas, J. F. (1992). J. Food Sci., 57, 829. Gross, U., Galindo, R. G. & Schoeneberger, H. (1983). Qual. Plant Foods Hum. Nutr., 32, 155. Jones, K. W. (1984). Proc. Recip. Meat Cont., 37, 52. Kinsella, J.E. (1979). JAOCS, 56, 242. Kinsella, J. E. & Damodaran, S. (1980). In Analysis and Control of Less Desirable Flavors in Food and Beverage. Academic Press, New York, USA, p. 95. Lecomte, N. B., Zayas, J. F. & Kastner, C. L. (1993). J. Food Sci., 58, 464. Leonard, P., Ruiz, Jr & Hove, E. I. (1976). J. Sci. Food Agric., 27, 667. Li-Chan, E., Nakai, S. & Wood, D. F. (1984). J. Food Sci., 49, 345. Lin, M. J. Y., Humbert, E. S. & Sosulski, F. W. (1975). J. Inst. Can. Sci. Technol. Aliment., S(2), 97. Lin, C. S. & Zayas, J. F. (1987). J. Food Sci., 52, 545. Mittal, G. S. & Usborne, W. R. (1985). Food TechnoI., 39, (4), 121. MSTAT (1985). Michigan State University. East Lansing, MI, USA. Padua, M. R. (1983). J. Food Sci., 48, 1145. Schmidt, G. R., Mawson, R. F. & Siegel, D. G. (1981). Food Technol., 35 (5), 235. Townsend, W. E., Witnauer, L P., Rillof, J. A. & Swift, C. E. (1968). Food Technol., 32(7), 62. Verma, M. M., Ledward, D. A. & Lawrie, R. A. (1984a). Meat Sci., 11, 109.
Infuence of protein isolate on processing and quality of frankfurters
Verma, M. M., Ledward, D. A. & Lawrie, R. A. (1984b). Meat Sci., 11, 171. Wang, C. R. & Zayas, J. F. (1992). J. Food Sci., 57, 726. Williams, C. W. & Zabik, M. E. (1975). J. Food Sci., 40, 502. Willing, M. D. (1974). JAOCS, 51, 128A. Wills, R. B. H. & Kabirullah, M. (1981). J. Food Sci., 46, 1657. Young, V. R., Scrimshaw, N. S., Torun, B. & Viteri, F. (1979). JAOCS, 56, 110. Zayas, J. F. & Lin, C. S. (1988). J. Food Sci., 53, 1587.
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