Validation of Pasteurisation Temperatures for a Tomato-Oil Homogenate (salmorejo) Processed by Radiofrequency or Conventional Continuous Heating.

Salmorejo is a viscous homogenate based on tomato, olive oil and breadcrumbs commercialised as a "fresh-like" pasteurised-chilled purée. Due to its penetration, dielectric heating by radiofrequency (RF) might improve pasteurisation results of conventional heating (CH). The objective was to validate the pasteurisation temperature (70-100 °C, at 5 °C intervals) for salmorejo processed by RF (operating at 27.12 MHz for 9.08 s) or conventional (for 10.9 s) continuous heating. The main heat-induced changes include: orangeness, flavour homogenisation, loss of freshness, thickening, loss of vitamin C and lipid oxidation. Both CH and RF equivalent treatments allowed a strong reduction of total and sporulated mesophilic microorganisms and an adequate inhibition of the pectin methylesterase, peroxidase and, to a lesser extent, polyphenol oxidase but did not inhibit the polygalacturonase enzyme. Pasteurisation at 80 °C provided a good equilibrium in levels of microbiological and enzymatic inhibition and thermal damage to the product. Increasing this temperature does not improve enzyme inactivation levels and salmorejo may become overheated. A "fresh-like" good-quality salmorejo can be obtained using either conventional or radiofrequency pasteurisers.

Polyphenol Extracts from Sage (Salvia lavandulifolia Vahl) By-Products as Natural Antioxidants for Pasteurised Chilled Yoghurt Sauce.

Sage by-product extracts (SE) are a valuable source of phenolic acids and flavonoids for food applications. The objective was to test two SE as antioxidants in pasteurised chilled yoghurt sauces against oxidation. Two SE of different polyphenol total content and profile were selected: SE38 (37.6 mg/g) and SE70 (69.8 mg/g), with salvianic and rosmarinic acid as the main polyphenols, respectively. Four experimental low-fat yoghurt sauces were formulated: untreated; SE70/2 (0.16 g/kg); SE38 (0.3 g/kg); and SE70 (0.3 g/kg). The stability of phenolic acids, microbiological quality (mesophilic bacteria, moulds and yeasts, and L. monocytogenes), and oxidative stability (lipids, colour, and pH) were studied in the sauces after pasteurisation at 70 °C for 30 min (day 0) and stored by refrigeration (day 42). Pasteurisation and further chilling ensured the microbiological quality and inhibition of microbial growth could not be evidenced, although SE70 showed some antimicrobial potential. Both SE showed good properties as antioxidants for yoghurt sauces. This finding was based on two results: (i) their main polyphenols, salvianic and rosmarinic acids, resisted to mild pasteurisation and remained quite stable during shelf life; and (ii) SE improved radical scavenging capacity, delayed primary and secondary lipid oxidation, and increased colour stability, contributing to sauce stabilisation. SE38 had a better antioxidant profile than SE70; therefore, the selection criteria for SE should be based on both quantity and type of polyphenols. Due to their stability and antioxidant properties, sage polyphenols can be used as natural antioxidants for clean-label yoghurt sauces.

Revalorisation of Sage (Salvia lavandulifolia Vahl) By-Product Extracts as a Source of Polyphenol Antioxidants for Novel Jelly Candies.

Sage (Salvia lavandulifolia Vahl) aqueous extracts (SE) obtained from distillation by-products were assessed as antioxidants for nutritionally enhanced jelly candies. Two experimental SEs with a different content of phenolic acids and flavonoids were tested: (i) SE38 (37.6 mg/g) and (ii) SE70 (69.8 mg/g), with salvianic and rosmarinic acids as main polyphenols, respectively. Flavour alteration, stability of sage polyphenols, physical quality traits and antioxidant capacity (AC) were studied in strawberry candies formulated without sugars and enriched with SEs at 0.25, 0.50 and 0.75 g/kg. Despite their different quantitative composition, SE38 and SE70 provided similar antioxidant properties, which were dose dependent. Salvianic and rosmarinic acids were stable without degrading to candy processing (up to 80 °C), keeping their antioxidant potential. There were no relevant differences in flavour or physical traits (pH, °Brix and CIELab colour) between untreated and SE-enriched strawberry candies. The addition of 0.75 g SE/kg resulted in relevant increases of candy AC: (i) from 30 to 38 mg GAE/100 g (total phenolics); (ii) from 10 to 17 mg TE/100 g (DPPH• radical scavenging assay); (iii) from 5 to 13 mg TE/100 g (ABTS·+ radical scavenging assay); (iv) from 84 to 163 µmol Fe2+/100 g (FRAP capacity) and (v) from to 75 to 83% (inhibition of deoxyribose damage). Sage distillation by-products can be revalorised as a source of natural antioxidants to produce healthier candies.

Assessment of a Diterpene-Rich Rosemary (Rosmarinus officinalis L.) Extract as a Natural Antioxidant for Salmon Pâté Formulated with Linseed.

The use of natural plant extracts with standardised antioxidant properties is a growing strategy to stabilise food products. The use of a rosemary lipophilic extract (RLE), obtained from the by-product of high-yield selected plants and rich in polyphenols (334 mg/g, with diterpenes such as carnosic acid and carnosol as main compounds), is here proposed. Four RLE doses (0, 0.21, 0.42 and 0.63 g/kg) were tested in a salmon pâté formulated with sunflower oil and linseed, which was pasteurised (70 °C for 30 min) and subjected to storage at 4 °C and 600 lux for 42 days. Rosemary diterpenes resisted pasteurisation without degrading and showed antioxidant activities during the shelf-life of pasteurised pâté. RLE addition led to increased peroxide value (from 3.9 to 5.4 meq O2/kg), but inhibited formation of secondary oxidised lipids such as malondialdehyde (from 1.55 to 0.89 mg/g) and cholesterol oxidation products (from 286 to 102 µg/100 g) and avoided discolouration (slight brownness) in the refrigerated pâté. However, this did not entail relevant changes in fatty acid content or in the abundance of volatile organic compounds from oxidised lipids. Increasing the RLE dose only improved its antioxidant efficacy for some oxidation indexes. Thus, the oxidative deterioration of these types of fish emulsion can be naturally controlled with rosemary extracts rich in diterpenes.

Rosemary Extracts Improved the Antioxidant Status of Low-Fat Yoghurt Sauces Enriched with Inulin.

Yoghurt sauces are considered fatty products which are quite susceptible to oxidation and must be stabilised using antioxidants. Novel formulations for yoghurt sauces often involve replacement of fat with dietary fibres and use of natural preservatives. The aim of the present research was to design healthier formulations for yoghurt sauces based on the replacement of sunflower oil (SO) with chicory inulin (IN) and the use of rosemary extracts (RE) as natural antioxidants. Different sauces were developed by adding IN at 2 and 5% w: w and/or 300 mg/kg lipo- and/or water-soluble rosemary extracts (RLE and/or RWE) containing 120 and 146 mg polyphenols per g extract, respectively. Nutritional value (proximate composition and caloric contribution), some physical properties (pH and CIELab colour) and antioxidant status (deoxyribose, DPPH radical scavenging, Rancimat, lipid peroxidation and linoleic acid assays) were assessed in the sauces. Replacement of SO with IN (5%) reduced fat content by 30%, roughly 15% low calories, thereby obtaining healthier sauces. As expected, the RLE was more effective than the RWE in improving antioxidant activity in lipidic environment. Using RLE enhanced the antioxidant capacity of lipid peroxidation by 44%. In the Rancimat test, this increased the oxidative protection of the sauce made with and without IN (5%) by around 20% or 45%, respectively. Similarly, using RLE doubled protection against linoleic acid oxidation. Application of IN in yoghurt sauce has nutritional (replacement of lipids with dietary fibre) and technological interest (foaming agent) and can be combined with RE of high polyphenol content as a potential functional ingredient capable of stabilising the sauces against oxidation.

Contribution of Green Propolis to the Antioxidant, Physical, and Sensory Properties of Fruity Jelly Candies Made with Sugars or Fructans.

Enrichment with phenolic compounds is proposed as a strategy to obtain more stable and healthier candy products. A green propolis ethanolic dry extract (PEE) from Braccharis dracunculifolia (Brazilian Alecrim-do Campo) was assessed as an antioxidant in jelly candies. Three levels (0, 0.01, and 0.02% w/w) of PEE were tested in jelly candies alternatively made with two carbohydrate bases (sugars or fructans) and three fruity dyes and flavours (menthe, orange, or strawberry). Propolis polyphenol content (identified by HPLC-MS and quantified by HPLC-DAD/UV-Vis), antioxidant capacity (total phenolics and radical scavenging activity), physical properties (moisture, pH, CIELab colour, and texture profile analysis), and flavour were studied in candies. PEE was rich in polyphenols (>8.7%), including several prenylated p-coumaric, caffeoylquinic and diterpenic acids, and flavonoids, with Artepillin-C (3.4%) as the main bioactive compound. The incorporation of PEE into the hot liquor at 80 °C for 5 min before moulding allowed a good retention of propolis polyphenols in the final product (recovery percentages of up to 97.4% for Artepillin-C). Jelly candies made with sugars or dietetic fructans have poor antioxidant properties, which depend on the dyes and flavours used. Using PEE (at 0.02%) strongly improved the antioxidant capacity (relative increases of up to 465%) of candies without altering the pH, colour, or texture, although off-flavour may appear. Propolis, due to its good antioxidant properties, has potential for use as a functional ingredient in jelly candies.

Assessment of Rosemary (Rosmarinus officinalis L.) Extract as Antioxidant in Jelly Candies Made with Fructan Fibres and Stevia.

Enrichment with rosemary antioxidants is proposed as a possible strategy to obtain healthier jelly candies. Two aqueous rosemary extracts (RE) containing 73.9 (RE74) and 145.6 (RE146) mg polyphenols per g fresh weight were assessed as antioxidants in jelly candies based on fructooligosaccharides, inulin and stevia. Up to 15 phenolic acids, flavonoids and diterpenes were determined in the extracts, with rosmarinic acid as the main active compound. Sensory tolerance, physical properties, rosmarinic acid recovery, polyphenol content, and antioxidant capacity were determined in jelly candies. The threshold of sensory detection was established at 0.26 g RE146/kg of raw candy, below which rosemary off-flavours were avoided without altering pH, brix, texture, CIELab colour, and consumer acceptance. Adding 0.26 g RE146 per kg increased (p < 0.001) polyphenol content from 197 to 411 µg GAE/g and the antioxidant capacity from 1.77 to 4.14 µmol Trolox/g. Rosemary polyphenols resulted in being resistant to cooking, acted as secondary antioxidants and showed good interaction with the other jelly ingredients. Aqueous extracts from rosemary distillation by-products can be incorporated at acceptable levels to jelly candy formulations leading to higher oxidative stability and an increased content of dietary polyphenols.