The increase of iron and magnesium content in the studies by Naumova et al. was similar to our results despite the much higher amount of hemp flour used , which again proves that the hemp flour differs between the producers. It was assumed that hemp protein or hemp flour due to their high protein content could improve the products’ water holding capacity similar to soy proteins. However, the cooking losses were comparable with the other hemp ingredients tested. A possible reason may be the presence of edestin, which is an abundant protein in hemp. The typical pH of meat is 5.6–6.0 and it was proved that edestin aggregates in pH lower than 7.0 , therefore its water holding capacity or fat absorption capacity may be low in meat batters. The poor functional properties of hem protein isolate resulting from protein aggregation are probably caused by the presence of covalent disulphide bonds between proteins and high free sulfhydryl content . The slightly lower cooking losses in the meat loaves containing hemp ingredients may be still a promising result from a technological point of view. The hardness of the meat loaves increased in all of the samples containing the hemp ingredient, except for the DHS product which was comparable with the control. As this was the only variant in which the hemp shell is almost fully removed it may be assumed that any constituents increasing the water holding capacity are located in the hemp shell. No other TPA parameters were affected by the hemp ingredients . The texture parameters changes depend on the type and amount of ingredient used and the interactions between the additive and the meat batter. Walnut green husk addition increased the hardness of the meat samples, but at the level of 3 g per 100 g of meat the chewiness decreased . Sausages with lower chickpea protein concentrate addition were significantly harder and more chewy compared to those with higher amount of the same isolate . In another experiment, trim tray pollen the hardness and shear force decreased in sausages in which the fat was replaced by two types of tragacanth gum .
The colour parameters changed depending on the hemp ingredient used . All of the additives are dark in colour. Hemp flour and hemp protein are green, hemp seeds are brownish, even the de-hulled seeds contain small shell particles. That is why, the control product was lighter and its redness was higher compared to the other products. Hemp flour and hemp protein decreased the a* value the most significantly compared to the other products, because of their green colour. Parameter b* increased significantly only in the product with hemp flour. Green colour in meat products may be associated with the spices used during the production process, but generally it is not acceptable if the origin of such a colour is unknown for a consumer. As it is shown on Fig. 1, the addition of hemp flour and protein created lumps in the middle of the meat and fat particles giving unusual, odd cross section image.It is clear, that some modififications in grinding should be made in order to get a more even cross-section image of a product.The fatty acids profile changed significantly depending on the hemp ingredient used. PUFA amount doubled after the addition of hemp seed or de-hulled hemp seed. ALA was almost 5 times higher in these products compared to the control. The LA content also doubled in HS and DHS. The presence of both ALA and LA, which are essential fatty acids, in such amounts is important from a physiological point of view. Without a source of linoleic and α-linolenic many normal metabolic processes in the human organism may be affected. The lack of essential fatty acids may cause skin scaling or poor wound healing. It was proved that n3 fatty acids positively affect mental health parameters, insulin metabolism, total testosterone, hirsutism, few inflammatory markers and oxidative stress. CLA is a term describing various isomers of linoleic acid, which have two double bonds. These isomers are considered to be biologically active. The CLA content in non-ruminant meat is usually lower than 1 mg/g of lipid . The percentage of CLA in the analysed pork loaves was generally low and even slightly lower in the samples with the hemp additives. This might be due to heating of the samples since thermal treatment affects CLA oxidation resulting in creation of some significant volatile compounds which depends on the temperature and time of heating . PUFA protect from the development of cardiovascular diseases and they help to keep a proper composition of sperm, retina or brain lipids .
Very low levels of n3 acids are found in Western diets together with higher n6 acids intake, and meat products contain very low amounts of essential fatty acids . Therefore, any improvement of a product in this aspect should be beneficial. The content of both n6 and n3 fatty acids increased significantly in meat loaves with hemp seed and de-hulled hemp seed. As the hemp flour and hemp protein are defatted products , the increase of the unsaturated fatty acids was not significant. The specific values of the n6 to n3 ratio in the human diet are mentioned in literature, but it has been emphasised that this ratio may be associated with very low or very high overall PUFA intake. The absolute values of these fatty acids should be considered rather in a healthy diet composition . Nutritional indexes based on the fatty acid composition: AI, PI, TI and HH were calculated for the meat loaves. Oxidation has negative nutritional and organoleptic effects caused by changing the chemical structure of various substances and creation of toxic compounds . Products with high PI number are more susceptible for oxidation. Both HS and DHS had significantly higher PI indexes compared to the other products. Ulbricht and Southgate proposed two indexes: AI and TI which could characterise artrogenic and trombogenic fat properties. These indexes should be kept at low level to decrease the risk of cardiovascular diseases. Again, both HS and DHS had significantly lower AI and TI indexes than the other meat loaves. The HH index show the fatty acids influence on cholesterol metabolism. Higher HH values indicate better products from the nutritional point of view . HH values obtained in this study ranged from 1.64 in HF to 2.38 in DHS. All the calculated values prove that both HS and DHS are the additives which improve the nutritional value of the tested products.Fat stability and rancidity problems occur in products containing unsaturated fatty acids . One of the products of lipid degradation is malondialdehyde described as a very toxic substance. The products created in its reactions with nucleic acids bases induce mutations in bacterial and mammalian cells .
That is why it is important to control the level of malondialdehyde not only from the sensory or technological perspective, but most importantly because of the consumers’ health. The TBARS changes in the analysed samples during storage are presented in Fig. 2. There were no statistical differences between the samples on the first or the 8th day after production. A surprisingly high increase of fat oxidation products occurred after 15 days of storage in the control and the sample with de-hulled hemp seed. TBARS in the other samples were comparable and stable throughout the whole storage period. This effect could be caused by the substances present in the hemp shell. Both hemp protein and flour are by-products of fat extraction in which the hull is present. Comparing the studies by Vonapartis et al. , who analysed ten hemp cultivars and some additional studies on hemp oil , it is clear that the phenolics are mainly located in the hull. The average value obtained by Vonapartis et al. was 2224 mg/100 g, while the oils contained from 44 to 188 mg/100 g. That relation was confirmed by Chen et al. , who indicated two specific antioxidants: trans-caffeoyltyramine and cannabis in B. Both of them exhibited strong radical scavenging activity and were found in high amounts in the hemp seed hull.Various food additives – especially of plant origin – may increase the microbial load because of their high contamination. One of the sources of microbiological contamination of meat products, may be the addition of dried herbs and spices . In all of the analysed products the storage time had a significant effect on the multiplication of mesophilic aerobic microorganisms . None of the preparations inhibited or increased the multiplication of the total number of microorganisms in relation to the control; there were also no differences between the variants. The results helped to confirm that the hemp additives used in this study do not introduce any additional microbial contamination. Moreover, those ingredients do not stimulate the microbial growth in any way over the 15 d refrigerated storage.The consumer tests results are presented in Fig. 4. The texture of all the products was comparable for the consumers.
Despite the fact, that there were visible differences between the products in appearance , they were statistically comparable in the consumers’ rating. It is possible that in a product containing minced meat, non-meat ingredients may be associated with spices which are usually used and do not decrease consumers’ evaluation. Juiciness and taste of the control sample were graded significantly higher than the same attributes of most of the samples with hemp ingredients. However, the difference between the control and the meat loaf with de-hulled hemp seed was not significant. The overall acceptability results clearly show that the products with hemp ingredients are not acceptable with some tendency to grade the product with de-hulled hemp seed higher. Quite the opposite results were obtained by Naumova et al. who used 5, 10 and 15% of hemp flour in beef cutlets. The products with 10% of this ingredient were acceptable to the panellists while in our study the 5% addition decreased the products’ quality significantly. It is possible that the products’ sensory perception strongly depends on their other constituents. Verbeke stated that the functional product is acceptable if it is tasty, although the willingness to compromise on the taste for health decreased. In this study, the consumers’ willingness to buy the products with hemp seed additives increased after providing the information about the healthy ingredient . The question “would you buy?” was asked of each product twice. The second time it was developed into: “would you buy if you knew that the product contains omega 3 acids?”, trim bin tray giving a signal to a consumer that probably this tested product actually contains that healthy ingredient. Omega 3 acids are among the ingredients that are recognised by consumers as health promoting . For the control sample, the amount of positive answers did not change after asking the second question. However, for the products with hemp ingredients there was a substantial increase.
The meat loaf with de-hulled hemp seed was generally graded higher and the consumers declared their willingness to buy such a product, so the positive answers to the second question changed by only 12%. The most significant increase was noted for the product with hemp flour from 34 to 64 positive answers – which is over an 88% increase. For hemp seed and hemp protein products the change was comparable: 57 and 54% respectively. These results clearly show that functional meat products which are not fully acceptable in terms of sensory attributes have a chance to be implemented on the market only if the information about their health properties is provided. As was confirmed by Oliveira et al. , the consumers pay attention to the label, but the graphics seem to be its key component. In terms of increasing the role of the functional foods in influencing society’s healt hand well-being, a proper marketing strategy, including the label design, would be crucial.Fats and oils are major lipid components of human diet, generally obtained from plant seeds. In the last decades the interest in using non-drug hemp seeds for oil and flour production is growing , increasing its cultivating all over the world. In fact, in addition to the traditional uses , other innovative industrial applications are developing together with the interest to the hemp seeds as source of bio-active compounds for production of value-added products and supplemented food, as well as cosmeceuticals and nutraceuticals .