A comparative study on oxidative and hydrolytic stability of monovarietal extra virgin olive oil in bakery products

Effect of Refining Degree on the Quality Changes and Lipid Oxidation of Camellia (Camellia oleifera) Oil during Heating

Refining degree has an important influence on the quality of camellia (Camellia oleifera) oil. The deterioration behaviors and lipid oxidation of three kinds of camellia oils, including camellia crude oil (CO), moderate refined oil (MRO), and refined oil (RO), during heating were investigated in this study. The results of deterioration behavior analysis showed that the oxidation degree was RO > CO > MRO. Tocopherol and polyphenolic substances in the oil might help delay oil oxidation. The lipid oxidation results indicated that the heating process had greater effects on CO and MRO than RO; it upregulated neutral lipid content and downregulated phospholipid content in terms of lipid changes and the multiplicity of differences. Glycerophospholipid metabolism was the most remarkable pathway and was important to study the heating process of refined oil. Moderate refining is good for retaining the beneficial lipids in camellia oil. The results of this study would provide a theoretical basis for camellia oil processing.

Nutritional Improvement of Gluten-Free Breadsticks by Olive Cake Addition and Sourdough Fermentation: How Texture, Sensory, and Aromatic Profile Were Affected?

There is a growing need for gluten-free bakery products with an improved nutritional profile. Currently, gluten-free baked goods deliver low protein, fiber, and mineral content and elevated predicted glycaemic index (pGI). Olive cake (OC), a by-product from virgin olive oil extraction, is an excellent natural source of unsaturated fatty acids, dietary fiber and bioactive molecules, including polyphenols and tocopherols. In this framework, this study aimed at using two selected lactic acid bacteria and a yeast for increasing the antioxidant features and the phenol profile of the gluten-free breadsticks fortified with OC with the perspective of producing a functional food. Control (CTR) samples were prepared and compared with fermented ones (fCTR). Samples were added with either non-fermented OC (nfOC) or fermented for 12 and 20 h (fOC-12 and fOC-20). Our results showed that the predicted glycemic index (pGI) was influenced by both OC addition and sourdough fermentation. In fact, the lowest value of pGI was found in fOC-12, and hydrolysis index and pGI values of samples with OC (fOC-12 and nfOC) were statistically lower than fCTR. Both OC addition and fermentation improved the total phenol content and antioxidant activity of breadsticks. The most pronounced increase in hardness values was observed in the samples subjected to sourdough fermentation as evidenced both from texture profile analysis and sensory evaluation. Moreover, in most cases, the concentration of the detected volatile compounds was reduced by fermentation. Our work highlights the potential of OC to be upcycled in combination with fermentation to produce gluten-free breadsticks with improved nutritional profile, although additional trials are required to enhance textural and sensory profile.

Red grape skin extract and oat β-glucan in shortbread cookies: technological and nutritional evaluation

Consumers are increasingly interested in innovative products enriched with nutrients that counteract the development of civilisation-associated diseases. Thus, the development of new functional nutrient-enriched food products that meet consumer needs is therefore necessary. The aims of this study were to develop a novel shortbread cookie product by addition of red grape skin extract and oat β-glucan and to evaluate the influence of these modifications on physico‐chemical properties and consumer’s acceptance. The red grape skin extract used in this product is a source of polyphenols which are beneficial for human health and extend product shelf life. β-glucan is a soluble fraction of dietary fibre that helps to lower reduce blood cholesterol and glycemic levels. The influence of grape skin extract, β-glucan and a combination of both on the β-glucan content, colour and texture parameters, thermal properties, total antioxidant activity, total phenolic content, volatile compounds profile and sensory properties of shortbread cookies was analysed. Product with modified formulations had higher total antioxidant activity, total phenolic content and were was more thermally stable than control samples. The obtained innovative functional products were characterized by an increased content of oat β-glucan, which is desirable from a nutritional point of view. The DSC measurements showed higher oxidative stability of cookies enriched with β-glucan and red grape skin extract. The additives caused significant changes in the colour and profile of volatile compounds of the finished final product but did not affect the sensory acceptance among consumers. The use of these additives represents a development in food technology that may be valuable in the food industry to increase the nutritional value and extend the shelf shelf-life of bakery products.

Oxidative Stability and Antioxidant Activity in Canned Eels: Effect of Processing and Filling Medium

The effect of canning and the use of different filling media (sunflower oil, olive oil, and spiced olive oil) on oxidation parameters (acidity, peroxide value (PV), and thiobarbituric acid reactive substances (TBARS) index), antioxidant capacity, and total phenol and vitamin E contents in eels was studied. A preliminary frying treatment caused a decrease in titratable acidity and an increase in TBARS, antioxidant capacity, and vitamin E in the eel muscle. During sterilization, TBARS also increased significantly. The magnitude of the changes depended on the filling medium. Storage also had a significant effect on oxidation parameters in eel muscle and in filling media. After one year of storage, the sunflower oil and canned eels packed in this oil presented higher antioxidant capacity and vitamin E content than olive oil, spiced olive oil, or canned eels packed in these oils. However, the total phenol contents were higher when olive oil or spiced olive oil were used as filling media. Despite the losses, the results show that the canning process and subsequent storage preserved a great part of the antioxidant capacity and vitamin E content of the filling medium, which is of interest to the consumer. Both sunflower oil and olive oil as filling media are of great nutritional interest.

Effects of an Extract from Olive Fruits on the Physicochemical Properties, Lipid Oxidation and Volatile Compounds of Beef Patties

The aim of this work was to evaluate the effect of an olive extract (OE) on the physicochemical and microbiological characteristics, lipid oxidation and volatile compounds of beef patties stored both aerobically and under modified atmosphere packaging for 15 days at 4 °C. The antioxidant and antimicrobial effects of the OE were compared to those of sulfite. Four formulations were elaborated according to the antioxidant and dose used: without antioxidant, C; 300 mg potassium metabisulfite/kg product, S; 150 mg OE/kg product, OE1; and 250 mg of OE/kg product, OE2. The parameters analyzed were pH, water activity, color, lipid oxidation (TBARS and volatile organic compounds: hexanal, 2-pentyl-furan, 1-pentanol, 2,3-octanedione and nonanal, 1-octen-2-ol) and total viable counts. The OE delayed the loss of the bright red color of the patties and reduced the lipid oxidation in both types of packaging compared to the control patty. Sulfite was the most effective antioxidant for inhibition of the total viable counts. An OE could be used as a natural antioxidant to delay the lipid oxidation of meat without negatively affecting its physicochemical properties.

Teff Type-I Sourdough to Produce Gluten-Free Muffin

The increasing number of persons following a gluten-free (GF) diet and the need for healthy and natural products are forcing researchers and industries to provide gluten-free products with high nutritional value. Here, a biotechnological approach combining the use of teff flour and type-I sourdough has been proposed to produce GF muffins with nutritional benefits. Teff-sourdough was prepared and propagated following the traditional daily refreshment procedure until the biochemical stability was achieved. The sourdough, dominated by Lactiplantibacillus plantarum, Limosilactobacillus fermentum and Saccharomyces cerevisiae strains, was used to produce muffins at three different levels (up to 15%, wt/wt) of fortification, achieving several positive effects on the nutritional properties of the products. The use of teff flour led to high content of fiber (>3 g/100 g) and proteins (>6 g/100 g) in muffins achieving the nutritional requirements for the healthy claims "source of fiber" and "rich in protein". Thanks to their metabolic traits, sourdough lactic acid bacteria caused the increase of the total free amino acids (TFAA, up to 1000 mg/kg, final concentration) and phytic acid decrease (50% lower than control), which positively affect the nutritional properties of the products. Besides, high in vitro protein digestibility (IVPD, 79%) and low starch hydrolysis rate (HI, 52%) characterized the fortified muffins. Muffins also presented high in vitro antioxidant (56%) and mold-inhibitory activities, potentially contributing to an extended shelf-life of the products.

Bioactive Compounds and Stability of a Typical Italian Bakery Products "Taralli" Enriched with Fermented Olive Paste

Olive paste (OP) is a novel by-product of olive mill industry composed of water, olive pulp, and skin. Due to its richness in bioactive compounds, OP exploitation for human consumption has recently been proposed. Starter driven fermented OP is characterized by a well-balanced lipid profile, rich in mono and polyunsaturated fatty acids, and a very good oxidative stability due to the high concentration of fat-soluble antioxidants. These characteristics make OP particularly suitable as a functional ingredient for food/feed industry, as well as for the formulation of nutraceutical products. New types of taralli were produced by adding 20% of fermented OP from black olives (cv Cellina di Nardò and Leccino) to the dough. The levels of bioactive compounds (polyphenols, triterpenic acids, tocochromanols, and carotenoids), as well as the fatty acid profile, were monitored during 180 days of storage and compared with control taralli produced with the same flour without OP supplementation. Taralli enriched with fermented OP showed significantly higher levels of bioactive compounds than conventional ones. Furthermore, enriched taralli maintained a low amount of saturated fatty acids and high levels of polyphenols, triterpenic acids, tocochromanols, and carotenoids, compared to the initial value, up to about 90 days in the usual conditions of retailer shelves.

Study of the Effect of Tyrosyl Oleate on Lipid Oxidation in a Typical Italian Bakery Product

Tyrosyl oleate (TO), synthesized using oleic acid and tyrosol, was added to the original receipt of tarallini, to evaluate its antioxidant effectiveness. Lipid oxidation in control sample and samples with 1%, 4%, and 7% of TO at different storage times (0, 15, 30, 37, and 45 days) was evaluated. Accelerated oxidation analysis showed that the control sample took more than four times to complete the oxidation compared tarallini with TO. The control sample and tarallini with 1% of TO exceeded the peroxide value limit after 30 days of storage and the other two final products after 45 days. The control sample registered a oxidized fatty acid concentration higher than all the samples formulated with TO. The concentration of volatile compounds from lipid oxidation in tarallini with TO showed a lower concentration than the control sample. All the determinations carried out confirm, for the first time, that TO can counteract lipid oxidation in a real lipid system.

Use of olive leaf extract to reduce lipid oxidation of baked snacks

Olive leaves are a waste of the olive oil processing industry and represent a good source of phenolic compounds. The aim of this work was to assess the influence of olive leaf extract (OLE) on lipid oxidation of baked snacks, like breadsticks, made with wheat flour, extra virgin olive oil (EVO), white wine, and salt. Two EVOs having different peroxide value and antioxidant profile (total phenol content, tocopherols, carotenoids, and antioxidant activity) were considered. The snacks were subjected to oven test or stored in the usual conditions of retailer shelves. The obtained data highlighted that EVO plays a key role both for the quality and for the shelf-life of baked snacks and the use of OLE is recommended especially when baked snacks are produced with low quality EVO which therefore does not have a good content of natural antioxidants. The OLE addition significantly reduced the forced oxidative degradation during oven test, as evidenced by a decrease of 27% in oxidation-related volatile compounds and of 42% in triacylglycerol oligopolymers compared to control snacks (CTR) without OLE. Moreover, OLE effectively acted also in normal storage conditions, improving sensory data, induction times, antioxidant activity, and volatile compounds compared to CTR (i.e. hexanal 165.49 vs 38.31 μg g^-1 in OLE-added). The amount of oxidation-related volatile compounds showed an opposite trend with the quality level of oil used.