4. Results and Discussion
4.3. Label compliance
Energy values were estimated (in kJ and kcal) and the seeds’ labels were compared with the results obtained, according to the tolerance ranges displayed in the guidance document for competent authorities for the control of compliance with EU legislation on: Regulation (EU) N.º 1169/2011 of the European Parliament and of the Council of 25 October 2011 on the provision of food information to consumers, amending Regulations (EC) No 1924/2006 and (EC) No 1925/2006 of the European Parliament and of the Council, and repealing Commission Directive 87/250/EEC, Council Directive 90/496/EEC, Commission Directive 1999/10/EC, Directive 2000/13/EC of the European Parliament and of the Council, Commission Directives 2002/67/EC and 2008/5/EC and Commission Regulation (EC) No 608/2004 and Council Directive 90/496/EEC of 24 September 1990 on nutrition labelling of foodstuffs And Directive 2002/46/EC of the European Parliament and of the Council of 10 June 2002 on the approximation of the laws of the Member States relating to food supplements with regard to the setting of tolerances for nutrient values declared on a label.
For the energy value, fibre represents 2 kcal/g and 8 kJ/g, carbohydrate and protein represent 4 kcal/g and 17 kJ/g, whereas fat represents 9 kcal/g and 37 kJ/g. The tolerances for the nutrition declaration on foods are for carbohydrate, protein and fibre (<10 g/100 g: ± 2 g; 10-40 g/100 g: ± 20% and >40 g/100 g: ± 8 g) and for fat (<10 g/100 g: ± 1.5 g; 10-40 g/100 g: ± 20% and >40 g/100 g: ± 8 g).
Regarding the results (Table 10, Table 11, Table 12 and Table 13), only flax, poppy and sesame’s fat and protein contents were within the tolerance ranges. All the other results were outside the tolerance ranges, allowing to conclude over- and underestimations of these values by the manufacturer.
62
Table 10 - Nutritional information from chia seeds’ label in comparison to the obtained results.
/100 g dw Label Tolerance Lower tolerance
Upper tolerance
Obtained
result Comparison
Energy value (kJ) 1825 - - - 1955 -
Energy value (kcal) 435 - - - 475 -
Fat (g) 25.8 ± 20% 20.6 31.0 35.2 Outside the
tolerance range
Carbohydrates (g) 23.0 ± 20% 18.4 27.6 0.2 Outside the
tolerance range
Dietary fibre (g) 26.8 ± 20% 21.4 32.2 40.4 Outside the tolerance range
Protein (g) 15.6 ± 20% 12.5 18.7 19.3 Outside the
tolerance range
Table 11 - Nutritional information from flaxseeds’ label in comparison to the obtained results.
/100 g dw Label Tolerance Lower tolerance
Upper tolerance
Obtained
result Comparison
Energy value (kJ) 2232 - - - 2132 -
Energy value (kcal) 534 - - - 518 -
Fat (g) 42.0 ± 8 g 34.0 50.0 41.6 Within the
tolerance range
Carbohydrates (g) 29.0 ± 20% 23.2 34.8 0.32 Outside the tolerance range
Dietary fibre (g) 27.0 ± 20% 21.6 32.4 36.8 Outside the tolerance range
Protein (g) 18.0 ± 20% 14.4 21.6 17.2 Within the
tolerance range
63
Table 12 - Nutritional information from poppy seeds’ label in comparison to the obtained results.
/100 g dw Label Tolerance Lower
Table 13 - Nutritional information from sesame seeds’ label in comparison to the obtained results.
/100 g dw
According to the previously mentioned regulation, the actual amount of a nutrient in a product may vary in comparison to the declared label value due to several factors: the
64 source of values (from literature and calculated by recipe instead of analysis), the accuracy of analysis, the variation in the raw materials, the effect of processing, nutrient stability, storage conditions and time.
The following aspects should also be taken in consideration to explain why a value is outside the tolerance range: the nutrient in question, the extent and nature of the deviation (over- or underestimation), natural high variation of the nutrient, including seasonality, particular high degradation rates of nutrients in some food matrices, particular high analytical variability of nutrients in a specific food matrix, particular low homogeneity of a product leading to particular high variation of nutrient content in a product that is not offset by the sampling procedure, compliance of the majority of samples from the lot with the tolerance range, validity of the manufacturer's process for establishing the declared nutrient value and how the self-monitoring of the company functions.
65 4.4. Compilation of all obtained results
All the results obtained for chia, flax, poppy and sesame’s samples are reported on Table 14, Table 15, Table 16 and Table 17, respectively.
4.4.1. Chia
Table 14 - All results of chia’s oil, cake and whole seed.
Parameter Oil Cake Whole seed Results of FA are presented in relative percentage (%). C16:0 - palmitic, C16:1 - palmitoleic, C18:0 - stearic, C18:1 - oleic, C18:2 - linoleic, C18:3 - linolenic, C24:0 - lignoceric acids, SFA - Saturated, MUFA - Monounsaturated, PUFA - Polyunsaturated fatty acids, TPC – total phenolic compounds, GAE – gallic acid equivalents, TFC – total flavonoids content, ECE – epicatechin equivalents, FRAP – ferric reduction antioxidant power, FSE – ferrous sulphate equivalents, DPPH• – 2,2-diphenyl-1-picrylhydrazyl, TE – trolox equivalents, TDF – total dietary fibre, dw – dry weight, ND - not detected. *mmol FSE/100 g.
66 4.4.2. Flax
Table 15 - All results of flax’s oil, cake and whole seed.
Parameter Oil Cake Whole seed Results of FA are presented in relative percentage (%). C16:0 - palmitic, C16:1 - palmitoleic, C18:0 - stearic, C18:1 - oleic, C18:2 - linoleic, C18:3 – linolenic acids, SFA - Saturated, MUFA - Monounsaturated, PUFA - Polyunsaturated fatty acids, TPC – total phenolic compounds, GAE – gallic acid equivalents, TFC – total flavonoids content, ECE – epicatechin equivalents, FRAP – ferric reduction antioxidant power, FSE – ferrous sulphate equivalents, DPPH• – 2,2-diphenyl-1-picrylhydrazyl, TE – trolox equivalents, TDF – total dietary fibre, dw – dry weight, ND - not detected. *mmol FSE/100 g.
67 4.4.3. Poppy
Table 16 - All results of poppy’s oil, cake and whole seed.
Parameter Oil Cake Whole seed Results of FA are presented in relative percentage (%). C16:0 - palmitic, C16:1 - palmitoleic, C18:0 - stearic, C18:1 - oleic, C18:2 - linoleic, C18:3 - linolenic, C20:0 – arachidic acids, SFA - Saturated, MUFA - Monounsaturated, PUFA - Polyunsaturated fatty acids, TPC – total phenolic compounds, GAE – gallic acid equivalents, TFC – total flavonoids content, ECE – epicatechin equivalents, FRAP – ferric reduction antioxidant power, FSE – ferrous sulphate equivalents, DPPH• – 2,2-diphenyl-1-picrylhydrazyl, TE – trolox equivalents, TDF – total dietary fibre, dw – dry weight, ND - not detected. *mmol FSE/100 g.
68 4.4.4. Sesame
Table 17 - All results for sesame’s oil, cake and whole seed.
Parameter Oil Cake Whole seed Results of FA are presented in relative percentage (%). C16:0 - palmitic, C16:1 - palmitoleic, C18:0 - stearic, C18:1 - oleic, C18:2 - linoleic, C18:3 - linolenic, C20:0 - arachidic, C20:1 - eicosenoic, acids, SFA - Saturated, MUFA - Monounsaturated, PUFA - Polyunsaturated fatty acids, TPC – total phenolic compounds, GAE – gallic acid equivalents, TFC – total flavonoids content, ECE – epicatechin equivalents, FRAP – ferric reduction antioxidant power, FSE – ferrous sulphate equivalents, DPPH• – 2,2-diphenyl-1-picrylhydrazyl, TE – trolox equivalents, TDF – total dietary fibre, dw – dry weight, ND - not detected. *mmol FSE/100 g.
69 4.5. Oil yield
Oil yield results are presented on Table 18. Regarding our samples, after the cold-pressing process, when comparing the oil content in the cakes and the whole seeds, the oil recovery yield was: in chia 78%, in flax 75%, in poppy 72% and in sesame 40%. Therefore, the highest oil yield was registered for chia. The lowest recovery of oil was found in sesame, even though this seed has the highest content of fat in its composition, allowing to conclude that the cold-pressing method is not as effective in this sample for oil removal in comparison to the others.
Table 18 - Oil content in whole seeds and cakes of chia, flax, poppy and sesame and respective oil yields.
Whole seed Oil content (% dw) Cake Oil content (% dw) Oil yield (%)
Chia 35.2 Chia 7.8 78
Flax 41.6 Flax 10.3 75
Poppy 41.4 Poppy 11.5 72
Sesame 54.6 Sesame 32.8 40
Coates and Ayerza (1996) reported chia seed oil yields which can vary from 32.2 to 38.6, this can be explained by different climatic conditions, agronomic, fertilization and irrigation practices to which the crops are subjected (21, 123).
The lowest oil yield registered for sesame seed could be enhanced if the seeds were roasted before the pressing process. Roasting provokes changes in the microstructure, chemical composition and physical state of oilseeds by promoting cell damage, oil accumulation and enzymatic inactivation. Furthermore, the Maillard reaction reduces sugars with free amino acids, what improves sesame oil flavour and its antioxidant activity during high-temperature roasting. However, inadequate roasting temperatures may permanently damage the protein and the application value of the cake would be loss (47).
5. Conclusion
To conclude, the oils can be consumed preferentially raw, for instance, as salad dressings, providing essential FA (ALA and LA) and vitamin E (α-tocopherol) contents to the organism. Due to their expensive price when commercialized, they may be restricted to
70 an exclusive market segment. Therefore, they can have other potential applications, for instance, therapeutic purposes through topical application and further uses in the cosmetic industry or even in the industry of paints and varnishes. Regarding the oil extraction process, chia had the highest oil yield after cold-pressing, whereas sesame had the lowest and the resulting cake was still very rich in oil.
The cakes evidenced great potential for formulation of functional foods, nutraceuticals and incorporation in various food products, for example, baked goods (bread, biscuits and cookies), energy/cereal bars, beverages, pastas or even yogurts, as they are a high source of protein and especially dietary fibre. The consumption of dietary fibre provides several health benefits and stimulates the gastrointestinal microbiota, increasing health and well-being. Moreover, the cakes are rich in phenolic compounds and flavonoids, presenting high antioxidant activities which can provide benefits for human health when these cakes are consumed. Thus, instead of discharging the cakes or giving them as fodder to animals after the oil extraction, they could be incorporated in the food industry chain and valorised for human consumption.
The whole seeds, besides protein and dietary fibre, also present high contents of fat, which can provide essential FA and vitamin E contents as well, and important contents of phenolic compounds and flavonoids with antioxidant activity. They are also suitable to be incorporated in foodstuffs, either in whole or milled form. In the current food market, the products which include seeds in its composition is increasing and this pattern is likely to rise in future years due to consumer’s search for natural products with minimal processing and addition of preservatives and stabilizers. Additionally, the absence of gluten in these seeds, allows its consumption by coeliac patients.
Nevertheless, the nutritional and healthy features conveyed by the consumption of these seeds/cakes/oils can be mainly noticeable when included in a healthy and varied food pattern and in an active lifestyle.
Regarding the label compliance, flax, poppy and sesame fat and protein contents were within the tolerance ranges. The other results were outside the tolerance ranges with under- and overestimated values by the manufacturer.
Lastly, further studies are needed using different extracting solvents and methods to analyse the efficiency of those in the compounds’ extraction. More research is also recommended to evaluate the shelf-life period and best storage conditions for these products, to assess the bioavailability of bioactive compounds after digestion, to validate
71 the biological effects on human body, in order to obtain conclusive interpretations of the outcomes of their intake and effects on human health.
6. Work presented and published during the Master's course:
Participation and oral communication “Trends in human diets: Seeds as a source of fibre”
in XX Euro Food Chem in FFUP (17 to 19/06/2019), co-authorsM. Antónia Nunes, Liliana E. Santo, Anabela Costa, Manuel Álvarez-Ortí, José Pardo, M. Beatriz Oliveira;
Oral communication “Incorporation of ancient seeds in modern human diets” in Fascination of plants Day Seminary in FFUP (16/05/2019);
Review article: Melo D, Machado TB, Oliveira M. Chia seeds: an ancient grain trending in modern human diets. Food Funct. 2019;10(6):3068-89 (doi: 10.1039/c9fo00239a).
Participation and oral communication “Emerging trends in oils consumption: the case of chia, flax and sesame” in IJUP'19 – 12th edition (13 to 15/02/2019), co-authorsM. Antónia Nunes, Sílvia Bessada, Manuel Álvarez-Ortí, José Pardo, M. Beatriz Oliveira;
Article “Health Benefits of Chia Seeds’ Dietary Consumption” in EC Nutrition Journal, published at 30/10/2018, co-author M. Beatriz Oliveira;
Participation and poster communication “Chia seed oil: a n-3 fatty acid source” in XXIV Encontro Luso Galego de Química (21 to 23/11/2018), co-author M. Beatriz Oliveira;
Participation and Poster communication “Chia seeds: A review of the current knowledge”
in IJUP'18 – 11th edition (7 to 9/02/2018), co-authors Francisca Rodrigues, M. Beatriz Oliveira.
72
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