The most interesting characteristic of the oil obtained from C. sativa seed is the high content of polyunsaturated fatty acids , represented especially by linoleic and α-linolenic acids. Moreover, it has been reported that unsaponifiable fraction provides health benefits , in fact minor lipid components are of great interest because they affect the nutritional value and quality of the oil . Moreover, these compounds might be used for oil authentication , in fact their amount varies depending on the variety, agronomic conditions, processing methods and storage conditions . On the other hand, high unsaturation feature makes HSO chemically unstable, so the presence of bio-active molecules with antioxidant power is important for its stability. The presence of tocopherols, and in particular the high content of γ-tocopherol, and a smaller amount of other three isomers and tocotrienols, are primarily responsible for the stability of HSO, but also for providing vitamin E . It should be taken into account that tocopherols themselves are vulnerable to oxidation processes if exposed to light and heat sources, during processing and storage, leading to the loss of the antioxidant properties of the oil. In addition, because of their free radical scavenging ability, tocopherols are also helpful in preventing degenerative diseases, such as cardiovascular and Alzheimer’s diseases . Furthermore, the health benefits of HSO are also due to the presence of phytosterols, bio-active components currently receiving much interest for treatment of hypercholesterolemia and prevention of cardiovascular diseases . In fact, several guidelines recommend the intake of 2–3 g/day of plant sterols and/or stanols in order to reduce low-density lipoprotein-cholesterol levels.
Moreover,phytosterols have excellent oxidative prevention functions.Other bio-active compounds in HSO are represented by carotenoids, pollen trim tray which in addition to the provitamin A activity, can act as antioxidants and reduce the risk of degenerative diseases.The intensive dark green color of HSO is associated with the high content of pigments, especially chlorophylls, whose presence may cause adverse effects because of their susceptibility to photo-oxidation, decreasing the oil stability, healthiness, and organoleptic properties.The presence of carotenoids in HSO can also protect chlorophylls from degradation and prevent any color change during storage.Many findings regard the fatty acid % composition of the main HSO lipid components but, to the best of our knowledge, only few information is reported about the minor lipid compounds. To deepen this aspect, the present research focuses on HSO minor lipid components, in fact the qualitative and quantitative profiles of phytosterols, aliphatic alcohols and tocopherols have been determined, together with chlorophyll and carotenoid contents. Furthermore,as a preliminary study, multivariate statistical approach was used to make a comparison between Italian and Extra-European HSO samples. However, its high percentage in saturated fatty acids which has been associated with a series of diseases like obesity, cardiovascular and chronic diseases,is being a real problem for nowadays consumers who are really worried about their health, requesting healthier foods. A way to please this demand is by reformulating meat products with healthier lipid sources , especially from vegetable oils. The type of fat and lipid composition are not only interesting from a nutritional point of view but also have a significant role in the structure, texture, sensorial and technological properties of the final product . For this reason, several strategies have been applied to replace animal fat with vegetable oils minimizing both, their effect on the physicochemical and sensorial properties of the final product, to ensure their acceptability by consumers, but also on their technological characteristics, to ensure their technological viability in the meat industry.
One way of doing this substitution, with minimal technological effects, could be the use of gelled emulsions. Several vegetable oils with healthy lipid profiles and emulsifier or gelling agents have been successfully used in the development of these GEs . Moreover, previous studies have shown the potential of these GEs as animal fat replacers in several meat products, mainly cooked meat products . Among the variety of meat products, burgers and patties seem to be a compelling choice for both fat reduction and lipid profile improvement since they are popular products sold as ready-to-eat and fast food consumption, easy to prepare at home, and so, with a high impact in our diet. Although GEs are been highly applied as animal fat replacers in meat products, to our knowledge, there are no published data using the combination of hemp oil or chia oil with amaranth flour to elaborate GEs for fat replacer in burgers production. Chia oil is composed of a well-balanced fatty acids profile, consisting of up in the unsaturated fatty acid fraction with 65% linolenic acid and 20% linoleic acid . Hemp oil is rich in polyunsaturated fatty acids, mainly linoleic acid and also contains gamma and alpha linolenic acids . On the other hand, amaranth is a highly nutritious pseudocereal known to be a dietary source of proteins, vitamins, minerals and dietary fiber . Additionally, amaranth proteins provide emulsifying and gelling properties, both highly useful for the development of gelled emulsions . Therefore, the aims of this work were to evaluate the technological viability of using GEs, elaborated with hemp or chia oil with amaranth flour, as partial animal fat replacer for beef burgers production and study the effect of these two partial fat substitutions on proximate composition, lipid profile, lipid oxidation, and physicochemical, cooking, and sensory properties of reformulated beef burgers. In raw burger, the effect of replacing animal fat with GEs did not cause any effect on ash and protein content. However, the moisture values increased while the fat values decreased in beef burgers containing GEs, compared to control ones. The increase in moisture content was due to the water added to prepare the GEs. The same finding has been reported by several authors when used GEs as animal fat replacers in meat products . The reduction in fat content when the animal fat was replaced by the GEs was not influenced by the type of GE used but occur in a concentration-dependent manner . When both GEs were used at 25% of fat substitution in burgers, the level of fat reduction achieved was 12%, while GEs were used at 50% of fat substitution, the level of reduction increased until 33% compared to control burgers, without differences between gelled emulsion elaborated with chia oil and gelled emulsion elaborated with hemp oil.
This behavior was also observed by several authors.Thus, Lucas-Gonz´ alez et al. who replaced animal fat with chia-chestnut gelled emulsion in pork burgers reported a reduction of the fat content when substitution level increased. Similarly,Regarding nutritional claims, only burgers with the highest GEs substitution level can be considered as “reduced fat content”. In cooked burger, again no statistical differences were found among the control sample and reformulated samples for protein and ash content while in the case of fat and moisture content the same behavior than raw burger was observed. Regarding raw burgers, as expected, significant differences were detected in the fatty acid profile of burgers depending on both, the type of fat used and the level of pork fat replacement . From the total of fatty acids identified in control burgers, oleic , palmitic , linoleic , stearic , and palmitoleic fatty acids make up 91% of total fatty acids. To reach this level, in the case of reformulated burgers, the contribution of the α-linolenic fatty acid must be considered. In general, it could say that the use of GE as partial animal fat replacer in burgers decreased the amount of palmitic ,stearic and oleic fatty acids and increased the amount of linolenic and α-linolenic fatty acids.The most evident difference between burgers due to the type of GE used was the amount of linolenic and α-linolenic fatty acids. Burgers with amaranth-chia GE showed the highest amount of α-linolenic fatty acid while burgers with amaranth-hemp GE showed the highest amount of linolenic fatty acid. This is in accordance with the fatty acid composition of the corresponding vegetable oils. According to European Association, raw and cooked BCh50 and cooked BCh25 could be labeled with the nutritional claim as “high n-3 fatty acids”, since they contained more than 0.6 g α-linolenic acid per 100 g of the product . For the cooked samples, the trend is very similar regarding the influence of the percentage of substitution and the gelled emulsion used. Some small variations in the values and so in the statistical significance in cooked sample respect to obtained in raw samples could be attributed to the loss of fat and water during cooking.
Among the saturated fatty acids , grow tent in all burgers, the largest proportions were palmitic , stearic ,and myristic fatty acids. The replacement of animal fat by GE in burgers decreased the SFA content depending on both, the substitution level and type of GE used.This fact has also been reported by other authors in the case of replacement of animal fat by vegetable or marine oils in several meat products.Control burgers showed the highest amount of SFA, , therefore BH50 showed the lowest, with a decrease of 17% and 12.5% respectively, with respect to control ones. In the case of monounsaturated fatty acid content, a reduction was also reported due to the use of GE, showing control samples the highest content . It is important to notice that MUFA was the predominant fraction in all burgers being oleic acid the predominant. On the contrary, polyunsaturated fatty acid fraction increased in reformulated burgers, compared to control ones, being this increase higher at higher GE replacement level and also when amaranth-hemp GE was used . Linoleic and α-linolenic fatty acids are responsible for this increase. 3.2.2. Health indices of burgers Table 4 shows the health indices of cooked beef burgers.In relation to the PUFA/SFA ratio, it is observed an increase when animal fat is replaced by GE, due to both, the decrease in SFA and the increase in PUFA contents. This increase depends on both, substitution level and type of GE. All reformulated burgers are in accordance with the recommendations of the PUFA/SFA ratio that should be above than 0.4 . Regarding the n-6/n-3 index, all reformulated burgers, except BH25 are in accordance with the recommended value which must be less than 4 . As can be seen in Table 4, this index was widely improved by the use of GE with respect to control burgers.
The indices TI, AI and h/H have been proposed as good indicators of healthy food products and have been widely calculated and discussed to address the healthy characteristics of fats in meat products . Regarding that, TI and AI should be as low as possible and h/H ratio the other way around, as higher as possible. In view of that, the influence of pork back fat replacement by GE in burgers was positive considering that TI and AI indices decreased and h/H ratio increased.All these changes observed are directly related to the percentage of pork backfat replace: the most positive values in the three indices were shown in burgers with 50% substitution.Several authors have used these indices to highlight the healthy properties of using vegetable oils in substitution of animal fats in meat products.The physicochemical properties of raw and cooked beef burgers formulated with amaranth flour and chia or hemp oil gelled emulsions as partial pork backfat replacers were shown in Table 5. Regarding raw burgers, the main values of pH and Aw were not affected by addition of GEs in burgers as partial substitute of pork backfat. Similarly, Lucas-Gonz´ alez et al. found no differences on pH and Aw values in burgers when emulsion gels formulated with chestnut flour and chia oil were used as a substitute of pork backfat. Lightness , yellowness and hue of burgers were not influenced by the used of gelled emulsions. Quite the opposite, redness and chroma were significantly affected by this replacement although their variation was not quantitatively relevant. In fact, redness values ranged from 4.06 to 5.72 . Similarly, Barros et al. found no differences in the color parameters of the beef burgers added with oil emulsions. On the contrary, several authors reported that the addition of gelled emulsions, in different meat products, were able to affect all color parameters.