Coffee is one of the most popular beverages in the world due to its rich flavor and beneficial effects on human health
Several coffee substitutes are present in the market. They come from different parts of roasted plants (leaves, roots, fruits, and seeds)
Due to its nutritional composition, white lupin seed is widely used in a variety of potential food applications, including fermented foods (tempeh and miso), milk substitutes, bakery products, pasta, and snacks
The production of coffee substitutes from Lupinus albus seeds exposes them to roasting, which is an important step to obtain aroma, color and flavor characteristics similar to those of coffee, this process allows to improve their digestibility, nutritional value, and antioxidant properties
Therefore, this study aims to determine the optimal roasting conditions (temperature and time) obtaining a better sensory and nutritional quality of coffee substitutes. These conditions are attained by using the design of experiment methodology, more precisely the response surface (RSM). Which has the advantage of reducing the number of experimental cycles needed to provide sufficient information to establish the optimal roasting conditions.
Lupinus albus seeds were purchased from the local market of Khemis Miliana in ALGERIA, those of uniform size and without defects were used for roasting. All reagents were purchased from Sigma, Aldrich (France): DPPH, Folin-Ciocalteu reagent, and Gallic acid.
A 3-level, 2-factor full factorial design was used as the experimental design, as shown in
The responses: the parameters of color (L*, a* and b*), pH, extraction yield, phenolic content, DPPH scavenging activity, sugar content, protein content, ash content, and sensory properties (appearance, odor, flavor and overall impression) of the roasted beans, were related to the independent variables by a second-degree polynomial equation:
In this equation, β0 is a constant, β1 and β2 are linear coefficients, β11 and β22 are quadratic coefficients, and β12 is the interaction coefficient.
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1 |
160 |
-1 |
10 |
-1 |
2 |
240 |
+1 |
10 |
-1 |
3 |
240 |
+1 |
20 |
0 |
4 |
240 |
+1 |
30 |
+1 |
5 |
200 |
0 |
20 |
0 |
6 |
200 |
0 |
10 |
-1 |
7 |
200 |
0 |
30 |
+1 |
8 |
160 |
-1 |
30 |
+1 |
9 |
160 |
-1 |
20 |
0 |
Multiple regression analysis was applied using MODDE 13 (Umetrics, Sartorius, Germany) to fit the proposed model, including linear (x1, x2), quadratic (x11, x22) and interaction (x1x2) terms for the predictors (temperature x1, and time x2) to determine the regression coefficients and to draw the surface and contour plots. The significance levels of all terms in the proposed equation were determined statistically by calculating the F-value for p-values of 0.001, 0.01 or 0.05.
An ANOVA test was used to determine the effects of independent variables on dependent responses using SPSS software (version 26). The Tukey test was chosen to compare means at the p < 0.05 level.
Dehulled Lupinus albus seeds were poured into the electric rotary roasting drum (Wintop Wk-1, Wintop Machinery, China) and roasted under the conditions chosen for each experiment. The roasted seeds were cooled to room temperature, then packed in glass jars and stored at 4°C until use. Immediately before the preparation of the beverages, the roasted seeds were ground using a grinder (F2034210 Moulinex Krup France).
The extract was obtained according to the method of Youn and Chung
L* (darkness/lightness), a* (redness/greenness), and b* (blueness/yellowness) of the lupin seed samples were determined using a Chroma meter (CR400; Konica Minolta). To determine the degree of roasting, the L*-value is a good choice to control the color changes during the roasting process; it is equivalent to the color observation by the operator. The color parameters were measured in triplicate and the results are presented as means and standard deviations.
Five grams of roasted seeds were extracted with one volume of distilled water (50 mL) and then filtered through a filter paper (Whatman No. 2). The pH value of the aqueous filtrate was measured with a pH meter (HI 8417, Hanna Instruments, Italy).
A portion (10 mL) of each of the hot water extracted beverages was transferred to a weighing pan and dried at 105 °C, until the sample weight was constant. The extraction yield was expressed as the ratio of the weight of extracted solids to the weight of the initial sample.
The phenolic content of the hot water extracted beverage (previously obtained) was determined according to the Folin-Ciocalteu procedure used by Youn and Chung
The free radical scavenging activity of the hot water extracted beverage was determined using the DPPH radical according to the method used by Youn and Chung
The mixture was shaken vigorously and left for 10 minutes. The absorbance of the resulting solution was measured at 525 nm with a spectrophotometer (Shimadzu UV-1601, Japan). The radical scavenging activity was calculated using the following formula:
Proximate analysis was performed according to the procedures of the Association of Official Analytical Chemists
Sensory tests were carried out by a panel of 34 volunteers, all non-smokers (employees of the company ALGOFOOD, students and staff of the University Djilali Bounaama Khemis Miliana), and their ages ranging from 22 to 45 years, (14 women and 20 men). The drinks were served as 50 mL samples in white cups, which were coded with three numbers. The panels determined their preference based on sensory attributes such as appearance, odor and taste (flavor), and overall preference. For all attributes, a hedonic scale of 1 to 5 was used (1=low intensity; and 5=extreme intensity) to score the samples. Before the coffee tasting, all panel members were informed about the scoring rules. The data were presented as means and standard deviations.
The effects of roasting on the color properties of Lupinus albus seeds are presented in Table 2. The L* and a* values were found to be dependent on linear effects (p < 0.05) at roasting temperature, and the L* value was linearly related to time (p < 0.05).
The roasting process and technique affected the seed color values significantly (p < 0.05). The L* and b* values decreased while a* value increased with increasing roasting temperature and time (
During roasting, non-enzymatic chemical browning reactions promote the development of brown pigments that give roasted products a darker color
Yüksel et al.
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1 |
160 |
10 |
39.04±0.21i |
-1.71±0.02a |
2.87±1.07i |
Medium |
2 |
240 |
10 |
25.19±0.01e |
1.47±0.01g |
0.21±0.02a |
Dark |
3 |
240 |
20 |
19.64±0.30b |
1.70±0.01h |
0.58±0.02c |
Very dark |
4 |
240 |
30 |
16.21±0.02a |
2.09±0.02i |
0.43±0.01b |
Very dark |
5 |
200 |
20 |
28.35±0.04f |
1.12±0.01e |
1.22±0.01e |
Dark |
6 |
200 |
10 |
29.09±0.02g |
0.94±0.05d |
1.76±0.02f |
Medium dark |
7 |
200 |
30 |
21.25±0.02c |
1.25±0.02f |
0.72±0.01d |
Dark |
8 |
160 |
30 |
23.44±0.03d |
0.57±0.03c |
2.16±0.01g |
Dark |
9 |
160 |
20 |
29.17±0.07h |
0.19±0.02b |
2.36±0.01h |
Medium dark |
a
The variation of the brew pH is shown as a function of temperature and roasting time in
Fikry et al.
Extraction yield has been defined as the mass of soluble matter in the extract and can thus affect the sensory quality of the coffee-like Lupin beverage. The extraction yield tends to increase with increasing temperature and roasting time. These results can be explained by the softening of the seed texture for material flow and the decomposition of insoluble polymers by the roasting temperature
It can be seen that the highest extraction yield was obtained with a roasting temperature of 240 °C and a roasting time of 30 minutes (
The extraction yield was a function of linear (p<0.001) and quadratic (p<0.05) effects of roasting temperature and also of the linear (p<0.01) effect of roasting time, and related to the interaction (p<0.01) between temperature and time effect.
The effects of roasting on the antioxidant activity and total phenolic content of coffee-like Lupinus albus beverages are presented in
Phenolic content was linearly dependent on roasting temperature (p < 0.001) and time (p < 0.05). Quadratic and interaction effects of time were not significant (
The highest levels of phenolic compounds were obtained with a roasting temperature of 240 °C and a roasting time of 30 min (
According to Ee et al.
The DPPH radical scavenging activity increased with increasing temperatures and roasting times (
Similar results for antioxidant activity were obtained by
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1 |
160 |
10 |
5.91±0.01c |
0.08±0.02a |
11.21±0.04a |
55.62±0.2a |
12.87±1.42d |
37.27±2.03e |
2.82±0.10a |
2 |
240 |
10 |
4.81±0.49abc |
0.18±0.01f |
22.65±0.20g |
73.64±0.03ef |
1.24±0.50ab |
25.25±1.01bc |
3.20±0.03b |
3 |
240 |
20 |
4.46±0.30a |
0.23±0.30g |
23.31±0.50g |
80.23±1.00g |
0.89±0.04a |
20.73±0.07ab |
3.21±0.11b |
4 |
240 |
30 |
4.25±0.32a |
0.26±0.15h |
26.41±0.07h |
76.25±0.09fg |
0.10±2.14a |
17.98±0.08a |
3.81±0.01c |
5 |
200 |
20 |
5.21±0.72bc |
0.14±0.02d |
19.05±0.50e |
65.01±2.01cd |
4.49±1.06b |
31.29±1.23d |
2.81±0.10a |
6 |
200 |
10 |
5.62±0.17bc |
0.12±0.03c |
17.37±0.02d |
61.64±1.20bc |
10.17±2.07cd |
33.65±2.19de |
2.80±0.15a |
7 |
200 |
30 |
4.73±0.29ab |
0.16±0.30e |
20.06±0.30f |
74.54±1.30f |
1.74±0.04ab |
23.28±0.04b |
2.87±0.04a |
8 |
160 |
30 |
5.76±0.08bc |
0.09±0.20b |
14.92±0.06c |
57.31±0.04ab |
8.41±2.19c |
30.21±2.17cd |
3.74±0.07c |
9 |
160 |
20 |
5.72±0.01bc |
0.09±0.20b |
12.11±0.10b |
55.10±0.80a |
9.54±0.60cd |
32.64±3.12de |
2.67±0.08a |
Mean of three determinations ± standard error. Means have the same letters in the same line do not differ at p < 0.05. a-h Means having a different subscript within a column differ (P < 0.05)
Browning of roasted foods is mainly due to the development of non-enzymatic reactions such as the Maillard reaction and sugar caramelization
According to Youn and Chung
The highest free sugar content was obtained with the lowest roasting temperature and duration (160 °C, 10 min). The same observation was made for the protein content, which decreased significantly (p<0.05) during roasting (
Many researchers
However, Waszkowiak et al.
This shows that the heat applied during roasting and the interaction between the carbonyl group of the reducing sugar and the free amino acid of the protein in the Maillard reaction reduced the protein content.
These results suggest that lupin seeds used for coffee-like beverages should not be subjected to high temperatures and long roasting times during roasting because many nutrients, including carbonyl and amino compounds, are degraded in non-enzymatic browning reactions.
White lupin seeds are a rich source of minerals; their total content is 2.6-4.4 g/100g
This study shows that the ash content was significantly (p<0.05) higher in seeds roasted at 240°C, than in those roasted at 160°C (
The significant increase in ash content during the roasting process (
Sensory evaluation is very important for new product development. However, appearance, smell, flavor, and general acceptability are the main quality parameters of coffee
The results of the sensory evaluation (appearance, odor, flavor, and overall preference) are presented in the
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F |
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1 |
160 |
10 |
2.30±0.02ab |
2.12±0.02a |
3.03±0.01a |
2.73±0.21ab |
2 |
240 |
10 |
3.40±0.05bc |
3.75±0.05f |
3.41±0.01c |
3.06±0.10abc |
3 |
240 |
20 |
3.01±0.08abc |
3.14±0.02d |
3.31±0.25bc |
2.72±0.01ab |
4 |
240 |
30 |
2.05±0.50a |
2.01±0.07ab |
3.07±0.05a |
2.70±0.23a |
5 |
200 |
20 |
4.89±0.10e |
4.81±0.05g |
3.87±0.07f |
4.10±0.04d |
6 |
200 |
10 |
3.75±0.10cd |
3.32±0.03e |
3.36±0.03c |
3.21±0.24bc |
7 |
200 |
30 |
3.16±0.40bc |
3.67±0.01f |
4.21±0.05d |
3.49±0.02c |
8 |
160 |
30 |
3.81±0.90cde |
2.35±0.04c |
3.24±0.03abc |
3.08±0.09abc |
9 |
160 |
20 |
3.05±0.30c |
2.26±0.09bc |
3.11±0.50ab |
2.93±0.40ab |
Mean of three determinations ± standard error. Means have the same letters in the same line do not differ at p < 0.05. a-f Means having a different subscript within a column differ (P < 0.05)
The degree of roasting (roasting time and temperature) is a determining factor affecting sensory quality. The coffee substitute obtained from lupin beans roasted at 200°C for 20 min achieved the best score (p < 0.05) compared to the other beverages.
Coffee-like beverages obtained from beans, roasted at 160°C for 10 and 20 minutes, are light in color, while those roasted at high temperatures (240°C) for a long time (between 20 and 30 min), are very dark in color, and were rated poorly by the sensory panel in terms of odor, flavor and overall acceptability.
The results of the sensory analysis are consistent with the results of Bolek
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pH |
5.15333*** |
-0.55858** |
-0.23094* |
-0.02625 |
0.0375 |
-0.0768752 |
0.966 |
Yield extract |
14.5267*** |
5.88031*** |
1.81144** |
1.005* |
-0.30375 |
1.27687** |
0.997 |
TPC |
18.4178*** |
4.92624*** |
1.46647** |
-0.29375 |
0.460001 |
0.00937476 |
0.994 |
DPPH |
67.25*** |
8.96192* |
2.48261 |
-0.52875 |
-0.21000 |
0.1725 |
0.915 |
Ash |
2.62** |
0.142894 |
0.23094 |
0.31125 |
0.2325 |
-0.058125 |
0.807 |
Carbohydrate |
4.94556* |
-4.12661** |
-2.02506* |
0.03125 |
0.58625 |
0.6225 |
0.937 |
Proteins |
29.593*** |
-5.2192** |
-3.56514* |
-1.545 |
-0.209999 |
-0.0393753 |
0.971 |
Appearance |
4.31444** |
-0.101036 |
-0.0620651 |
-0.7475 |
-0.42875 |
-0.53625 |
0.839 |
Odor |
4.28889** |
0.313213 |
-0.167432 |
-0.9962* |
-0.4 |
-0.369375 |
0.854 |
Flavor |
3.84222*** |
0.0591784 |
0.103923 |
-0.46375 |
-0.0325 |
-0.103125 |
0.772 |
Overall preference |
3.73667*** |
-0.0375278 |
0.0389711 |
-0.5475 |
-0.15375 |
-0.133125 |
0.795 |
L* |
26.2411*** |
-4.41817* |
-4.67942* |
-0.58625 |
-0.0124998 |
1.24125 |
0.953 |
a* |
1.26* |
0.896336* |
0.463324 |
-0.28875 |
-0.17625 |
-0.31125 |
0.928 |
b* |
1.25222* |
-0.890563 |
-0.220836 |
0.15125 |
-0.02125 |
0.174375 |
0.963 |
Significance level: *** p ≤ 0.001; ** p ≤ 0.01;*p ≤ 0.05
To determine the optimal roasting conditions, Bolek and Ozdemir, (2017)
The results show that the optimal temperature and roasting time for preparing a coffee-like beverage from Lupinus albus seeds was 210 °C and 20 minutes.
The coffee substitute prepared from roasted Lupinus albus seeds is considered a bioactive beverage that can be used as a functional drink. White lupin seeds have substantial uses as they are an important source of protein, dietary fiber, minerals, essential fatty acids and active substances, which can be used as ingredients in the preparation of various foods.
The present study, therefore, describes the variations in the attributes of color (L*, a*, b*), pH, dry matter, total polyphenol content, antioxidant activity, sugar content, protein content, ash content, sensory properties, including the overall acceptability of the coffee substitute as a function of roasting conditions (Temperature and time) using a full factorial experimental design.
The results showed that roasting temperature and time significantly affected all parameters. These beverage qualities can be correlated to the roasting conditions using second-order polynomials. The optimal roasting temperature and time (210 °C, 20 minutes), were obtained graphically using contour plots.
In particular, more research is needed to determine the daily dose of the active components reported in these coffee substitutes for best use and to prevent any health hazards from over consumption, especially for long-term consumption.
We would like to thank the company ALGOFOOD and the University Djilali Bounaama of Khemis Miliana for allowing us to carry out this work.