Influence of ethanol/water ratio in ultrasound and high‐pressure/high‐temperature phenolic compound extraction from agri‐food waste

The valorisation and management of agri‐food waste are currently hot investigation topics which probe the recovery of valuable compounds, such as polyphenols. In this study, high‐pressure/high‐temperature extraction (HPTE) and ultrasound‐assisted extraction (UAE) have been used to study the recovery of phenolic compounds from grape marc and olive pomace in hydroalcoholic solutions. The main phenolic compounds in both extracts were identified by HPLC‐DAD. Besides extraction yield (total polyphenol and flavonoid content) and the antiradical power, polyphenol degradation under HPTE and UAE has also been studied. HPTE with ethanol 75% gave higher phenolic extraction yields: 73.8 ± 1.4 mg of gallic acid equivalents per gram of dried matter and 60.0 mg of caffeic acid equivalents per gram of dried matter for grape marc and olive pomace, respectively. In this study, the efficient combination of ethanol/water mixture with HPTE or UAE has been used to enhance the recovery of phenolic compounds from grape marc and olive pomace. HPLC‐DAD showed that UAE prevents phenolic species degradation damage because of its milder operative conditions.     

Bacterial diversity of Moutai‐flavour Daqu based on high‐throughput sequencing method

In this study, we investigated the bacterial diversity of Moutai Daqu, Zhongxing Daqu and Zhengjiu Daqu from Guizhou Province of China by high‐throughput sequencing method. Sequencing results showed that 35 bacterial families were detected in the three Daqu samples. More interestingly, Sporolactobacillaceae, Streptomycetaceae, Pseudomonadaceae, Actinopolysporaceae, Caulobacteraceae, Pseudonocardiaceae, Nocardiaceae and Methlobacteriaceae were reported foe the first time in Moutai‐flavour Daqu using high‐throughput sequencing method. In particular, Thermoactinomycetaceae and Bacillaceae were demonstrated to be the common dominant bacteria in the three samples. These new data offer a more complete view of comprehensive of high‐throughput sequencing method to understand bacteria diversity of Moutai‐flavour Daqu. Copyright © 2017 The Institute of Brewing & Distilling     

Oxidative stability of fish oil‐in‐water emulsions under high‐pressure treatment

Over the last decade, high‐pressure treatment has been of considerable interest as an alternative to thermal treatment for food preservation and processing. The impact of high‐pressure treatment on lipid oxidation in fish oil‐in‐water emulsions stabilised by 0.5 wt% whey protein isolate or sodium caseinate was investigated by determining thiobarbituric acid (TBA), propanal values and hydroperoxide values (PVs). The TBA value and the PV of all emulsions increased with increasing pressure at low temperature, indicating that lipid oxidation was promoted by high‐pressure treatment. The impact of high‐pressure treatment on the oxidative stability of lipids was increased when the temperature was increased as the TBA and propanal values were markedly enhanced by high pressure at high temperature. However, high‐pressure treatment did not affect the antioxidant properties of whey protein isolate and sodium caseinate in the fish oil‐in‐water emulsions, which may suggest that high‐pressure treatment does not alter the lipid oxidation pathway in emulsion systems. The promotion of lipid oxidation by high pressure is due mainly to increasing the pressure on a gas reaction shifts the position of equilibrium towards the side with fewer gas molecules.     

Relationship between growth of food‐spoilage yeast in high‐sugar environments and sensitivity to high‐intensity pulsed UV light irradiation

The relationship between prior growth of food‐spoilage yeast in high‐sugar environments and their subsequent survival postpulsed UV (PUV) irradiation was investigated. Test yeast were separately grown to early stationary phase in YPD broth containing increasing concentrations of glucose (1–50% w/v) and were flashed with ≤40 pulses of broad‐spectrum light at lamp discharge energy settings of 3.2, 7.2 and 12.8 J (equivalent to UV doses of 0.53, 1.09 and 3.36 μJ cm^?2, respectively) and their inactivation measured. Findings showed that prior growth in high‐sugar conditions (≥30% glucose w/v) enhanced the sensitivity of all nine representative strains of Zygosaccharomyces bailii, Z. rouxii and Saccharomyces cerevisiae yeast to PUV irradiation. Significant differences in inactivation amongst different yeast types also occurred depending on amount of UV dose applied, where the order of increasing sensitivity of osmotically stressed yeast to PUV irradiation was shown to be Z. rouxii, Z. bailii and >S. cerevisiae. For example, a 1.2‐log order difference in CFU mL^?1 reduction occurred between Z. bailii 11 486 and S. cerevisiae 834 when grown in 50% w/v sugar samples and treated with the uppermost test UV dosage of 3.36 μJ cm^?2, where these two yeast strains were reduced by 3.8 and 5.0 log orders, respectively, after this PUV treatment regime compared to untreated controls. The higher the UV dose applied the greater the reduction in yeast numbers. For example, a 1.0‐, 1.4‐ and 4.0‐log order differences in CFU mL^?1 numbers occurred for S. cerevisiae 834 grown in 15% w/v sugar samples and then treated with PUV dose of 0.53, 1.09 and 3.36 μJ cm^?2, respectively. These findings support the development of PUV for the treatment of high‐sugar foods that are prone to spoilage by osmotolerant yeast.     

Effects of high‐pressure processing and enzymatic dephosphorylation on phosvitin properties

BACKGROUND: Egg phosvitin could be a good source of functional peptides. Enzymatic dephosphorylation and high‐pressure processing combined with thermal treatment applied before proteolysis could produce phosvitin hydrolysates with different properties compared to its native form. RESULTS: Phosvitin structure was maintained overall during high‐pressure treatment of 600 MPa applied at an initial temperature of 65 °C regardless of the pH and duration of treatment, confirming the high structural stability of this phosphoprotein. Treatment of phosvitin with phosphatase increased the degree of dephosphorylation from 24% to 63%, after 2 and 18 h, respectively. Moderate dephosphorylation of phosvitin prior to proteolytic digestion improved its hydrolysis, allowing formation of peptides with a molecular weight lower than 17,000 kDa as determined by size exclusion chromatography. Angiotensin‐converting enzyme (ACE) inhibition and antioxidant activity of dephosphorylated and protease‐treated phosvitin was increased by 52% and 39%, respectively, as compared to protease‐digested native phosvitin. CONCLUSION: Enzymatic dephosphorylation before proteolysis mimicking in vivo gut conditions improved ACE inhibition and antioxidant activity of phosvitin hydrolysates. Copyright © 2012 Society of Chemical Industry     

Anti‐obesity effect of Liupao tea extract by modulating lipid metabolism and oxidative stress in high‐fat‐diet‐induced obese mice

Liupao tea (LPT) is traditional dark Chinese tea. The effect of LPT extract on high‐fat‐diet‐induced obese mice was investigated systematically. The results showed that LPT extract could reduce body weight and significantly alleviate liver damage and fat accumulation. LPT could also decrease the levels of alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (AKP), total cholesterol (TC), triglycerides (TG), and low‐density lipoprotein cholesterol (LDL‐C) and increase the level of high‐density lipoprotein cholesterol (HDL‐C) in the liver. It also decreased the serum levels of inflammatory cytokines, including tumor necrosis factor alpha (TNF‐α), interferon gamma (IFN‐γ), interleukin (IL)‐1β, and IL‐6 and increased the serum levels of anti‐inflammatory cytokines, including IL‐10 and IL‐4. Moreover, LPT improved the levels of total superoxide dismutase (T‐SOD), glutathione peroxidase (GSH‐Px), and catalase (CAT) and reduced the level of malondialdehyde (MDA) in the liver. Moreover, LPT could upregulate the mRNA and protein expressions of peroxisome proliferator‐activated receptor alpha (PPAR‐α), lipoprotein lipase (LPL), carnitine palmitoyltransferase 1(CPT1), and cholesterol 7 alpha‐hydroxylase (CYP7A1) and downregulate those of PPAR‐γ and CCAAT/enhancer‐binding protein alpha (C/EBP‐α) in the liver. It also increased the mRNA expression of copper/zinc superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), CAT, gamma‐glutamylcysteine synthetase 1 (GSH1), and GSH‐Px. The components of LPT extract include catechin, rutin, taxifolin, and astragalin, which possibly have a wide range of biological activities. In conclusion, our work verified that LPT extract possessed an anti‐obesity effect and alleviated obesity‐related symptoms, including lipid metabolism disorder, chronic low‐grade inflammation, and liver damage, by modulating lipid metabolism and oxidative stress.     

Effects of high‐pressure homogenisation on physicochemical characteristics of partially skimmed milk

The changes in partially skimmed milk (0.5% fat) physicochemical properties and proteins after high‐pressure homogenisation (HPH) at 100, 200 and 300 MPa were investigated. Processing parameters and changes in pH, ethanol precipitation stability, lightness, whey protein denaturation, hydrophobicity and viscosity were evaluated. No significant differences were found between milk pH and nonprotein nitrogen content before and after HPH. Ethanol stability, lightness and hydrophobicity increased when pressure was increased from 100 MPa to 300 MPa. Whey protein denaturation, evaluated through noncasein nitrogen, occurred only at 200 to 300 MPa, and viscosity increased just at 300 MPa. Therefore, HPH changed some milk physicochemical characteristics, mainly those related to protein content. These results highlight that HPH processing is a promising technology to improve partially skimmed milk mouth feel being suitable for dairy products manufacturing.     

Impact of formulation on high‐protein bar rheological and wear behaviors

Due to the popularity of high‐protein bars, many new formulations are being generated to meet consumer preferences. New formulations may have different mechanical behaviors that can negatively impact processing ability, which makes determining the effect of ingredients on processing ability important. Thus, the objective of this study was to determine the effects of major ingredients in high‐protein bars on their rheological and tribological behaviors. Two response surface designs of model high‐protein bars comprising whey protein isolate (WPI), high‐fructose corn syrup (HFCS), and either canola oil (first design) or vegetable shortening (second design) were evaluated. Rheological tests, including adhesion, strain and frequency sweeps, large amplitude oscillatory shear, and wear testing, were conducted to determine the impact of individual ingredients on high‐protein bar mechanical behaviors. Oil‐based formulations had greater adhesion at higher levels of HFCS, while shortening‐based formulations were affected by WPI more than HFCS, resulting in lower overall adhesive maximum forces. Formulas with higher levels of WPI had lower phase angles and greater extent of nonlinear viscoelastic and strain‐hardening behaviors, while formulas with higher lipid and HFCS levels had higher phase angles. Overall, ingredient ratios had a notable impact on both oil‐ and shortening‐based high‐protein bar rheological and wear behaviors, suggesting that rheological and tribological testing could be useful for indicating processing ability of high‐protein bars. The information gained in this study can be used by food manufacturers that produce cold‐extruded or laminated food products. The results can help predict the ability of various formulations to be successfully processed, decreasing product development, and reformulation time and expense.     

Effects of sodium tripolyphosphate on functional properties of low‐salt single‐step high‐pressure processed chicken breast sausage

Influences of sodium tripolyphosphate (STPP) contents (0.1, 0.2, 0.3 and 0.4%) on water holding capacity (WHC) and texture properties of low‐salt (1.2% NaCl) single‐step high‐pressure processed chicken breast sausages (LSSS‐HPP sausages) were evaluated. Results showed that WHC was improved (4–5%) by the addition of STPP. However, the STPP contents customarily used for cooked sausages (0.3–0.5%) were excessive for LSSS‐HPP sausages, causing a soft and tacky texture. Sausages containing 0.1% of STPP had the best taste according to the sensory evaluations. Chemical interactions plus Raman spectroscopic analysis revealed that STPP addition partly changed native structures of myofibrillar proteins. Furthermore, higher STPP contents in the meat batter prevented those proteins from high pressure denaturing and aggregating in the subsequent single‐step HPP procedure. Increased hydrogen bonds and decreased hydrophobic interactions explained the better WHC and softer texture. Therefore, 0.1% of STPP is the optimal content in the processing of new‐type LSSS‐HPP sausages.     

Increasing fermentable sugar yields by high‐pressure treatment during beer mashing

High‐pressure treatment, which is an effective means of enhancing enzymatic reactions, was implemented during beer mashing to increase the production yield of fermentable sugar (FS). The malt solution was heated (62, 67, and 72°C) under pressure [0.1 (1 atm), 2, 50 and 100 MPa], and the FS was measured. The amount of FS reached an equilibrium level, which was the highest at 67°C and at 2 MPa. The pressures were 2, 50, 100, and 0.1 MPa in decreasing order of FS amount at 67°C. The temperatures were 67, 72 and 62°C in decreasing order of FS amount at 2 MPa. With a mechanistic approach, only the effect of pressure on gelatinization was analysed. The gelatinization degrees were also higher at pressures higher than 0.1 MPa. This observation highlights the positive effect (increasing the FS yield) of high‐pressure treatment on beer mashing. Copyright © 2015 The Institute of Brewing & Distilling     

Overexpression of vacuolar H+‐ATPase‐related genes in bottom‐fermenting yeast enhances ethanol tolerance and fermentation rates during high‐gravity fermentation

Vacuolar H⁺‐ATPase (V‐ATPase) is thought to play a role in stress tolerance. In this study it was found that bottom‐fermenting yeast strains, in which the V‐ATPase‐related genes DBF2, VMA41/CYS4/NHS5 and RAV2 were overexpressed, exhibited stronger ethanol tolerance than the parent strain and showed increased fermentation rates in a high‐sugar medium simulating high‐gravity fermentation. Among the strains examined, the DBF2‐overexpressing bottom‐fermenting yeast strain exhibited the highest ethanol tolerance and fermentation rate in YPM20 medium. Using this strain, high‐gravity fermentation was performed by adding sugar to the wort, which led to increased fermentation rates and yeast viability compared with the parent strain. These findings indicate that V‐ATPase is a stress target in high‐gravity fermentation and suggests that enhancing the V‐ATPase activity increases the ethanol tolerance of bottom‐fermenting yeast, thereby improving the fermentation rate and cell viability under high‐gravity conditions. Copyright © 2012 The Institute of Brewing & Distilling     

Pickling brine treatment for possible recycling using high‐pressure homogenization

Pickling is a preservation method of vegetables by brine immersion. Residual pickling solutions cannot be reused owing to high yeast content and the presence of polygalacturonase, which may produce vegetable softening. It has been reported that high‐pressure homogenization can reduce enzyme activity and microbial population in liquid foods. An investigation was aimed at studying the effect of high‐pressure homogenization cycles on polygalacturonase activity and yeast survival of residual pickling solutions, from processing of six vegetables. Each pickling solution was pumped through a homogenizing valve at 69 MPa pressure and was recirculated up to 15 times. Yeast counts and polygalacturonase activity were determined in treated solutions after being subjected to 1, 2, 5, 10, and 15 pressure cycles. Untreated and thermally treated solutions were used for comparison. Up to 4 log reductions in yeast inactivation was observed after five high‐pressure cycles treatments, contrasted with only 2 log reductions in thermal treatment. No clear relationship between enzyme inactivation and the number of high pressure cycles, or a thermal parallel effect, were observed. Copyright © 2007 Society of Chemical Industry     

Possible nutritional and health‐related value promotion in orange juice preserved by high‐pressure treatment

Effects of high‐pressure treatment on the orange juice carotenoids (β‐carotene, α‐carotene, zeaxanthin, lutein and β‐cryptoxanthin) associated with nutritional (vitamin A) and health‐related (radical‐scavenging capacity) values were investigated. Various high‐pressure treatments (50–350 MPa) combined with different temperatures (30 and 60 °C) and times (2.5, 5 and 15 min) of treatment were assayed. The carotenoid content of the orange juice was analysed by HPLC‐UV, the vitamin A value was determined as retinol equivalents (RE) and the free radical‐scavenging capacity was evaluated using the DPPH (2,2‐diphenyl‐1,1‐picrylhydrazyl) radical model system. A storage study was carried out at refrigeration temperature (4 °C). High‐pressure treatments at 350 MPa produced significant increases of 20–43% in the carotenoid content of fresh orange juice (from 3.99 to 4.78–5.70 mg l^?1). A non‐uniform behaviour of high‐pressure treatments was detected. An increase in time (beyond 5 min) or temperature (above 30 °C) of treatment did not improve the amount of carotenoids extracted. Owing to better extraction of carotenoids, an increase in vitamin A value from 164 to 238 RE l^?1 (45%) was achieved with the 350 MPa/30 °C/5 min treatment. No correlation was found between the increase in carotenoid amount extracted and the free radical‐scavenging activity. © 2002 Society of Chemical Industry