Antioxidant Activity of Aqueous Extracts Obtained from By-Products of Grape, Olive, Tomato, Lemon, Red Pepper and Pomegranate.

The aim of this work was to study the antioxidant potential of aqueous extracts obtained from different by-products. The effectiveness of these extracts was compared with that of rosemary extract. Total phenol carotenoid and vitamin C contents, as well as in vitro antioxidant activity, were assessed. Phenol content was positively correlated with in vitro antioxidant activity in extracts, while carotenoids showed a less clear relationship. Vitamin C was associated with antioxidant activity in lemon and pepper pomace extracts. Extracts from olive, grape, and lemon by-products displayed the highest antioxidant activity (radical scavenging activity), this being similar to the activity of rosemary extracts. Moreover, the phenolic profile of the extracts was analyzed, revealing diverse phenolic compounds. Rosemary extracts contained the highest variety and quantity of phenolic compounds, while olive pomace extracts were rich in hydroxytyrosol and 4-hydroxybenzoic acid. Lemon and pepper extracts contained high amounts of tyrosol, and tomato extracts had abundant epicatechin. The PCA analysis distinguished extracts based on in vitro antioxidant activity, phenol, carotenoid, and vitamin C content, along with their phenolic compound profiles. This study emphasizes the capacity of aqueous extract by-products as valuable sources of antioxidants and highlights the importance of understanding their bioactive components.

Effect of Phenolic Compounds from Almond Skins Obtained by Water Extraction on Pork Patty Shelf Life.

The extraction of phenols from almond skin using water has not been applied before. The purpose of this study was to obtain aqueous extracts from almond skin to be added to pork patties to prolong their shelf life. Four different varieties of almonds were studied and aqueous extracts were obtained. The antioxidant capacity and composition of phenol compounds of the extracts were determined. Results showed that the use of water produces extracts with phenol compounds and antioxidant capacity, with the Antoñeta variety presenting the best performance in terms of antioxidant behavior. The most abundant phenolic compounds identified were isorhamentin-3-O-rutinoside, catechin and protocatechuic acid, all of them had a hydrophilic character due to the -OH groups in their molecules. The effect of almond skin extracts (ALMOND) on the shelf life of pork patties was compared with the effects of a control without extract (CONTROL NEG) and a control with sodium ascorbate (CONTROL POS). Throughout storage, values of pH, weight loss, headspace composition, color, TBARs and psychrotrophic aerobic bacteria were studied. CONTROL POS samples showed the lowest lipid oxidation values in comparison to CONTROL NEG or ALMOND extract samples.

Different dry hopping and fermentation methods: influence on beer nutritional quality.

BACKGROUND: Nowadays, the craft beer market is booming and the consumer trend for trying something new is increasing. Here, nine different treatments of a craft beer were realized in a pilot plant, studying fermentation and dry-hopping types. Quality parameters of the beer such as polyphenols, antioxidants, bitterness, colour and alcohol were analysed. In addition, an electronic nose was used to distinguish beer types. RESULTS: Results showed that dry hopping in maturation with warm temperature increased the bitterness from 33 to 40 IBUs. The treatment using two yeasts and two fermentation temperatures resulted in the highest antioxidant capacity of the beer (around 92%). Antioxidant activity was increased by late dry hopping using ale yeasts for fermenting. Principal component analysis performed with electronic nose data explained up to 97% of the total variability of the compounds in the study. CONCLUSIONS: Combined use of ale and lager yeasts seems to increase the antioxidant capacity and total polyphenol content of beer. Antioxidant activity is increased by late dry hopping. An electronic nose is a suitable device for discriminating the volatile profile complexity in beer. © 2020 Society of Chemical Industry.

Quality Traits of Dry-Cured Loins from Iberian Pigs Reared in Montanera System as Affected by Pre-Freezing Cure.

Iberian dry-cured loins from pigs fattened in Montanera are usually subjected to seasonal production, which could be overcome through freezing the loin before the curing process. Hence, three homogeneous batches (n = 15 per batch) were established to evaluate the effect of different pre-freezing cure (-20 ± 2 °C) times (three and six months) of raw material on main quality characteristics of dry-cured loins in comparison to those elaborated from unfrozen meat. All samples were subjected to similar seasoning and same curing length to obtain dry-cured loins. Results showed a decrease in lightness, redness, chrome and hue values, polyunsaturated fatty acids (PUFA), higher oxidative phenomena, and changes in rheological properties in fresh loins on account on freezing (p ≤ 0.05). Some quality parameters of dry-cured loins were affected by freezing, weight loss, and hardness being higher as well as salt content being lower. PUFA and Warner-Braztler Shear Force (p ≤ 0.05) also showed higher values in dry-cured loins from frozen meat than those elaborated from unfrozen counterparts.

Optimization of Extraction Conditions to Improve Phenolic Content and In Vitro Antioxidant Activity in Craft Brewers' Spent Grain Using Response Surface Methodology (RSM).

Extraction temperature, extraction time and liquid (water) to solid ratio were optimized in order to extract antioxidant phenolic compounds from brewers' spent grain (BSG). The extracts were analysed for their total phenol content (TPC) and antioxidant activity was measured using three different methods: 2,2-diphenyl-2-picrylhydrazyl (DPPH) free radical, 2,2'-azino-bis(3-ethylbenothiazoline-6-sulphonic acid) (ABTS), and reducing power (RP) assays. All the parameters except extraction time promoted different efficiencies for the extraction of antioxidant phenolic compounds. TPC extraction was higher at lower temperatures and lower liquid/solid ratios up to a certain point. In this sense, a decrease in TPC with increasing liquid/solid ratios took place until a 16:1 ratio and a plateau was reached beyond that ratio. The highest DPPH activity was reported for 30-35 °C and 60-90 min extraction and 60-90 min extraction with a 25 mL/g ratio. ABTS values increased as the liquid to solid ratio decreased, being positively correlated with TPC (R = 0.788; p < 0.01). The highest RP was achieved at 30-33 °C extraction temperature and 10-14 mg/mL v/w ratio and at 116-120 min extraction and 16-17 mg/mL ratio. Gallic acid accounted for the majority of the phenolic compounds found, followed by hydroxyphenylacetic acid, epicatechin, and protocatechuic acid. Sinapic, 4-hydroxy benzoic, and syringic acids were also found in lower quantities. Coumaric, vanillic, ferulic, and caffeic acids were present in very small amounts. All the extracts contained phenolics and showed in vitro antioxidant activity, but the extracts obtained by using 30 °C, 121.9 min, and 10 mL/g liquid/solid ratio exhibited the highest content in TPC and antioxidant potential. The aqueous extraction of a potentially bioactive extract from BSG was demonstrated to be an efficient and simple method to recover these value-added compounds.

Inhibition of cholesterol oxidation products (COPs) formation in emulsified porcine patties by phenolic-rich avocado (Persea americana Mill.) extracts.

The effect of phenolic-rich extracts from avocado peel on the formation of cholesterol oxidation products (COPs) in porcine patties subjected to cooking and chill storage was studied. Eight COPs (7α-hydroxycholesterol, 7ß-hydroxycholesterol, 7-ketocholesterol, 20α-hydroxycholesterol, 25-hydroxycholesterol, cholestanetriol, 5,6ß-epoxycholesterol, and 5,6α-epoxycholesterol) were identified and quantified by GC-MS. The addition of avocado extracts (∼600 GAE/kg patty) to patties significantly inhibited the formation of COPs during cooking. Cooked control (C) patties contained a larger variety and greater amounts of COPs than the avocado-treated (T) counterparts. COPs sharply increased in cooked patties during the subsequent chilled storage. This increase was significantly higher in C patties than in the T patties. Interestingly, the amount of COPs in cooked and chilled T patties was similar to those found in cooked C patties. The mechanisms implicated in cholesterol oxidation in a processed meat product, the protective effect of avocado phenolics, and the potential implication of lipid and protein oxidation are thoroughly described in the present paper.