3.1. Chemical Properties of Aleppo Pine Seeds
Table 2 provides an overview of some physical and chemical attributes of Aleppo pine seeds.
The average values of the index of the seeds and the bulk density of
P. halepensis seeds, cultivated in Algeria are represented in
Table 2. The index of the seeds and the bulk density in Aleppo pine seeds were 15.43 g and 0.39 (g/cm
3), respectively. These results are lower than those (51.00 g and 0.52 g/cm
3) reported, respectively, by Kadri et al. [
6] for Aleppo pine seeds from the same country. However, the obtained result for the index of the seeds is comparable to the value (17.7 g) reported by Schiller and Waisel [
19] for Aleppo pine seeds cultivated in Israel. The difference in the values found of the index of the seeds and the bulk density of Aleppo pine seeds could be related to the difference in the ecological environment and the genotype and phenotypic variability [
6]. The seed index and the bulk density of
P. halepensis seeds is a useful tool for the assessment of the potential milling yield. On the other hand, Khan et al. [
20] indicated that the seeds possessing a higher seed index and higher bulk density present a better potential for grinding and flour extraction.
As indicated in
Table 2, the moisture content registers at 5.6 g/100 g. A parallel outcome was observed by Cheikh-Rouhou et al. [
11] for
P. halepensis cultivated in Tunisia (5.2 g/100 g). However, there is a slight difference when compared to the findings of Kadri et al. [
6] for
P. halepensis cultivated in Algeria (7.86 g/100 g). This variance could potentially be attributed to differences in seed maturation, cone age, climatic conditions of the harvest site, drying technique, and storage conditions of the seeds. The overall moisture content of the examined
P. halepensis seeds falls within a comparable range to that of other intact dry seeds, such as
P. pinea,
P. pinaster, and
P. canariensis, which all exhibit humidity levels around 7–9 g/100 g [
6].
The Aleppo pine seeds cultivated in the Merouana region of Algeria exhibit a protein content of 28.34 g/100 g. This outcome closely aligns with the protein content discovered in Jordanian
P. halepensis seeds (29.8 g/100 g) as reported by Tukan et al. [
4]. However, Cheikh-Rouhou et al. [
11] found a protein content of 22.7 g/100 g in Tunisian
P. halepensis seeds. In comparison to leguminous seeds such as dry beans, lentils, and chickpeas, or cereal grains such as wheat, Aleppo pine seeds could be categorized as protein-rich seeds. They can be ranked alongside cereals and legumes due to their noteworthy protein content, serving as significant sources of nutrition abundant in essential amino acids and nitrogen [
6]. Vegetable proteins are a very good alternative to animal proteins, because of their low cost, abundance and diversity of their sources (legumes, cereals, and oilseeds), their adequate quality and nutritional value, their ease of digestion, their non-toxicity, and finally for their functionality [
21].
As shown in
Table 2, the carbohydrate content of
P. halepensis is recorded at 24.81 g/100 g. This outcome closely aligns with the carbohydrate content discovered for Tunisian
P. halepensis (25.7 g/100 g) by Cheikh-Rouhou et al. [
11]. The substantial presence of soluble sugars in these seeds contributes to a notable caloric intake. Additionally, Kadri et al. [
6] noted that the main sugar found in these seeds is sucrose.
The seeds constitute a substantial source of lipid, which represents 37.26 g/100 g of their composition. Compared to seeds grown in other regions, the oil content is greater than that reported by Bagci et al. [
22] (21.1 g/100 g) in seeds of Turkish pines and slightly higher than that reported by Tukan et al. [
4] (32.1 g/100 g), Al-Ismail et al. [
23] (31.25 g/100 g) in seeds of Aleppo pine cultivated in Jordan and Khouja et al., [
24] (33.7 g/100 g) in Tunisian Aleppo pine seeds, and less than that reported by Cheikh-Rouhou et al. [
11] (43.3 g/100 g) for
P. halepensis Mill. cultivated in Tunisia. These seeds offer a promising reservoir of essential fatty acids, making them a valuable energy source. In a broader context, pine seeds generally exhibit rich lipid content, with variations due to species differences, geographical influences, and environmental factors [
25,
26]. Compared to other oleaginous seeds such as sunflower and sesame,
P. halepensis seeds have a relatively lower lipid content [
6]. On the contrary, the lipid content in soybean seeds is less than that found in pine seeds [
27].
As presented in
Table 2, the total phenol content was 663.23 mg/100 g in
P. halepensis Mill., while the flavonoid content reached 28 mg/100 g. The obtained result of phenolic compounds is greatly exceeding the values reported by Salim et al. [
28] (479.6 mg/100 g) in Palestinian Aleppo pine seeds, Kadri et al. [
6] (371 mg/100 g) for Algerian
P. halepensis seeds and Dhibi et al. [
9] (72 mg/100 g) in Aleppo pine seeds collected from Tunisia. These results are in agreement with those obtained by Nasri and Triki [
29], who revealed that pine species grown in northern Algeria show significantly higher phenolic compound concentrations than those grown in Tunisia. Regarding flavonoids, the obtained content is lower than those found by Salim et al. [
28] (82 mg/100 g), Kadri et al. [
6] (80 mg/100 g), and Dhibi et al. [
9] (35 mg/100 g), respectively, in Palestinian, Algerian, and Tunisian Aleppo pine seeds. A multitude of factors, including growing conditions, geographic origin, fertilizer usage, soil composition, extraction solvents, climate type, provenance, and sunlight exposure, could contribute to these observed differences. In the last decade, there was a lot of focus on the potential health benefits of dietary plant polyphenols as antioxidants. According to epidemiological research, a diet reach in polyphenols protects against cancer, cardiovascular disease, diabetes, osteoporosis, and neurological diseases [
30].
Aleppo pine seeds consist of 6.52 g/100 g ash (dry matter) and are considered as a very good source of ash. Results are in line with results reported by Khouja et al. [
31]; 7.1 g/100 g while it was higher than that reported by Tukan et al. [
4]; 5.6 g/100 g and less than that reported by Cheikh-Rouhou et al. [
11]; 8.3 g/100 g. Compared to those of other conifer seeds, the ash content of
Pinus halepensis seeds was higher than that of
Pinus pinea (4.5 g/100 g) [
25],
Pinus pinaster (4.62 g/100 g), and
Pinus canariensis (4.84 g/100 g) [
6].
The results of mineral contents show also that
P. halepensis seeds contained significant amounts of important mineral elements (macro and micro constituents). Phosphorus was the most abundant element, followed by potassium, magnesium, and calcium. These elements are vital components of our food and are very important for the maintenance of good health. Other elements (Fe, Na, Zn, Mn, and Cu) were also detected in different amounts (
Table 3). The same profile of mineral was found by Kadri et al. [
6] but with slightly different values. From a nutrition point of view,
P. halepensis seeds offer noteworthy concentrations of microelements (Fe, Zn, Mn, and Cu). These elements can help significantly in meeting the daily mineral needs.
3.3. Chemical Composition of Biscuits
The basic determinations of moisture, carbohydrates, fat, protein, and ash presented in
Table 5 give an indication of the nutritive value of the prepared biscuits, but the values of these change depending on the mixture of raw materials used to make the biscuits.
As seen in
Table 5, the moisture content of the biscuit samples ranged from 2.27 to 3.52%, the biscuit B45% displays the lowest value, however the biscuits BC and B30% present the highest values. Baking is a very important process to achieve a good texture and the structure of the biscuits, the oven temperature affects the moisture loss during baking and the evaporation starts from the dough surface, achieving about a 2–4% moisture content in the final products. This process transforms the physical and chemical characteristics of the dough when baked in an oven, where the temperature and time will be accurately controlled. The decrease in moisture level could also mean better shelf stability and potentially limit the growth of microorganisms.
With the exception of carbohydrates, the ash, fat, and protein content of the composite biscuits increased proportionally with increasing incorporation of Aleppo pine seed flour. The results show that the control biscuit had the lowest protein content; however, the protein content of the composite biscuits was significantly influenced by the blending ratio. This was expected because Aleppo pine seed flour contain more protein than cereals, although the prevalent protein in wheat occurs as gluten, which is needed in baking. These results are in good agreement with the observations made by Alobo et al. [
36], who showed that the protein content increases with increasing in the rate of substitution of sesame seed flour, which is rich in protein. Wheat flour is low in protein (7 to 14%) and deficient in some amino acids, such as lysine [
37]; Aleppo pine seed flour, on the other hand, is higher in protein quantity than wheat flour, but is also deficient almost in all essential amino acids (Tukan et al.) [
4]. The combination of wheat flour and Aleppo pine seed flour can be used in the production of biscuits to provide benefits by increasing the dose of protein consumed and supporting certain amino acids which are present in limited quantities.
The fat content ranged from 29.41% to 35.11%, with the highest value observed in sample B45%. This is attributed to the higher fat content naturally present in Aleppo pine seeds. Algerian
P. halepensis seeds are notably rich in total oil content, containing around 37.26% (
Table 2), which positions them as valuable sources of essential fatty acids and energy. It is also worth noting the role of fats in extending the shelf life of food products.
The ash content of the biscuits demonstrated an increase with the incorporation of Aleppo pine seed flour, potentially due to the high mineral content (6.52%) present in Aleppo pine seed flour (
Table 2). From
Table 3, it can be seen that
P. halepensis seed flour contained significant amounts of important mineral elements (macro and micro constituents). These results are consistent with those found by Kadri et al. [
6] who demonstrated that
P. halepensis seeds are rich in appreciable mineral content, notably in phosphorus, potassium, magnesium, calcium, iron, and copper. These elements have important implications for health. The data obtained are broadly consistent with those obtained by Baljeet et al. [
38], who showed that the ash content of biscuits exhibited an increase with the addition of high-ash buckwheat flour.
In terms of carbohydrate content, significant differences were observed between the different biscuit formulations. We note that increasing incorporation of Aleppo pine seed flour caused a significant decrease in carbohydrate content, and this decrease can be explained by the low carbohydrate content (24.81%) present in Aleppo pine seed flour (
Table 2). These results are in agreement with Aly et al. [
39], who demonstrated that the addition of barley flour, which contains a low carbohydrate content compared to wheat flour, could lead to a reduction in the carbohydrate content of composite biscuits.
The total phenolic compound of biscuits ranged from 3.57 to 31.95 mg/100 g and the flavonoids compound content from 0.24 to 1.50 mg/100 g. The addition of Aleppo pine seed flour to wheat flour resulted in a significant increase in phenolic and flavonoids content of composite biscuits. On the other side, the Aleppo pine seed flour was significantly richer in phenolic and flavonoid compounds than composite biscuits (B15%; B30%; and B45%) and this could be due to the sensitivity of phenolic components to heat. Mahloko et al. [
1] indicated that the decrease in phenolic compounds is attributed to the fact that baked products drastically reduce levels of phenolic compounds because of the depolymerization of polyphenols and decarboxylation of phenolic acids that occur during thermal treatment. Moreover, Che Sulaiman et al. [
40] indicated that the most phenolic compounds are heat sensitive and easily oxidized, hence an upper limit temperature must be observed to preserve its useful components.
The energy value of the biscuits ranges from 538.03 to 568.11 kcal, the biscuit B15% presents the lowest value; however, the biscuit B45% registers the highest calorie content. This increase in energy value can be interpreted by the richness of the Aleppo pine seed flour in lipids (37.26%) and protein (28.34%).
The present findings indicate that the incorporation of Aleppo pine seed flour in biscuits has the potential to increase the nutritional value of these products through an augmentation in protein, fat, and ash content, while concomitantly leading to a reduction in carbohydrate content.
The principal component analysis (PCA) outcomes offer lucid insights into the relationships between physicochemical parameters and the distinctions among the composite biscuit formulations. The PCA captured 87.20% and 9.31% of the variability through PC1 and PC2, respectively (
Figure 2). By scrutinizing the correlation matrix, it becomes apparent that a correlation exists between polyphenols, flavonoids, fat, protein, and ash parameters in the physicochemical profile of composite biscuits. Conversely, a discernible separation emerges between the energy value and moisture content of the composite biscuits. According to the first axis, B45% contains the higher energy, fat, protein, ash, polyphenols, and flavonoids levels, while displaying lower carbohydrate and moisture contents. On the contrary, the control biscuit (CB) exhibits elevated carbohydrate content as well as reduced protein, fat, ash, polyphenols, and flavonoids. However, B15% and B30% demonstrate intermediary outcomes. In essence, the current findings underscore that the introduction of Aleppo pine seed flour into biscuits has the potential to enhance the nutritional value of these products through an increase in protein, fat, ash, polyphenols, and flavonoids content, associated with a concurrent reduction in carbohydrate content.
3.4. Sensory Properties of Biscuits
The biscuits, prepared from a mixture of Aleppo pine seed flour and wheat flour, were subject to an evaluation based on their color, taste, crispness, appearance, and overall acceptability, utilizing a 9-point hedonic scale (
Table 6).
Color represents an essential quality attribute in the field of food industries as it has an immense influence on consumers choice and preferences [
41]. The color evaluation scores of composite biscuits decreased from 6.55 to 4.19. The control biscuit (CB) showed the highest score, while the lowest score was given to B 45%. On the one hand, the incorporation of Aleppo pine seed flour changes remarkably the color of the biscuits and makes it darker, which reduces the color preference of consumers, but on the other hand, the increasing of the Aleppo pine seed flour rate significantly improved the protein, lipid, ash, polyphenols, and flavonoids content of the composite biscuits. The color of the biscuits not only indicates the suitability of the raw materials used for preparation, but also provides a cue about the formulation as well as the quality of the end product. These findings are consistent with study by Elkatry et al. [
42] and Aksoylu et al. [
43], that documented changes in biscuit color brought about by the addition of byproducts such as seeds. On other hand, baking alters also the color of the biscuit surface, this darker appearance in biscuits was attributed to the Maillard reaction between the amino acids and sugars of the biscuits, which is often desired in baked goods [
42,
44]. These brown pigments are also produced due to the sugar caramelization during the baking process [
45].
In terms of taste, the subjects felt a more pronounced bitterness in the biscuit containing the highest quantity of flour (B45%), whereas the sweetness was discerned in all other biscuit samples.
Crispness is a force required to break biscuit structure rather than deform it when it is chewed with the human teeth [
46]. The crispness scores ranged from 7.12 to 8.31, the B45% showed the highest score, while the lowest score was presented by the control biscuit. The results obtained show a significant increase in the score of crispness as the composite flour supplementation increased, this observation can be attributed to the granular and slightly heterogeneous nature of Aleppo pine seed flour.
The appearance of the product makes the first impression in the consumer’s mind. The average appearance score for our biscuits ranged from 5.27 to 8.51; the highest score was found in the control biscuit (CB), while the lowest score was obtained with B45%. This corresponds to the findings of Khouja et al. [
31], who stated that, the most preferred sample is the one which has the smallest quantity of defatted dough of Aleppo pine seeds, unlike the one containing the largest quantity.
The sensory scores for the overall acceptability of the developed biscuits, as well as the control sample, ranged from 5.33 to 7.91. The control biscuit and sample B15% have the best scores than other biscuits samples. The overall acceptability score for the entire biscuit was above five. Meilgaard et al., [
47] showed that an overall acceptability score higher than 5 is considered as an acceptable standard score. The evaluation of the sensory quality of the prepared biscuits shows that the control biscuit and sample B15% demonstrated the most preferred choices.