Effect of high‐pressure homogenisation on the retention of selected aroma compounds in model dairy emulsions

The aim of this work was to investigate the effects of high‐pressure homogenisation on the aroma retention of mixed sodium caseinate–whey protein (2% + 2% w/v) emulsions. For this purpose, raw and pasteurised emulsions, with different fat contents (5%, 8% and 15% w/v) and subjected to different homogenisation pressures (0, 18, 100 and 150 MPa), were produced. The retention of seven aroma compounds (hexanal, benzaldehyde, diacetyl, ethyl butyrate, isoamyl acetate, ethyl hexanoate and ethyl octanoate) was evaluated by static headspace gas chromatography. Results showed that aroma release was affected by the presence and the quantity of the lipid phase. As regards homogenisation, an increase in the retention of hexanal with homogenisation pressure was observed and interactions between hexanal and caseinate were suggested. Benzaldehyde showed significant changes in headspace partition with increasing pressure only in the 5% fat content emulsions, whereas no homogenisation effect on aroma retention was observed for diacetyl or esters.     

Protective role of Punica granatum (pomegranate) peel and seed oil extracts on diethylnitrosamine and phenobarbital-induced hepatic injury in male rats

The present study is an attempt to reveal the protective role of Punica granatum peel and seed oil extracts against diethylnitrosamine (DEN) and phenobarbital (PB) induced hepatic injury in rats. DEN administration increased the levels of malondialdehyde (MDA), DNA fragmentation, caspase-3 and glutathione reductase (GSR) activities, while the level of reduced glutathione (GSH) and the activities of superoxide dismutase (SOD), glutathione S-transferase (GST) and total glutathione peroxidase (t-GPx) were decreased compared with the control. Treatment with peel and seed oil extracts pre, during and post DEN administration improved liver functions, decreased the levels of MDA, DNA fragmentation, caspase-3 and GSR activities with an elevation in levels of GSH, SOD, GST and t-GPx activities. This indicates that these extracts reduced the oxidative stress and apoptosis induced by DEN. Also the effect of administration of PE and SOE separately for a long time (23 weeks) on healthy rats was studied.     

Physicochemical Properties,Minerals, Trace Elements,and Heavy Metals in Honey of Different Origins: A Comprehensive Review

Honey is a popular natural food product with a very complex composition mainly consisting of both organic and inorganic constituents. The composition of honey is strongly influenced by both natural and anthropogenic factors, which vary based on its botanical and geographical origins. Although minerals and heavy metals are minor constituents of honey, they play vital role in determining its quality. There are several different analytical methods used to determine the chemical elements in honey. These methods are typically based on spectroscopy or spectrometry techniques (including atomic absorption spectrometry, atomic emission spectrometry, inductively coupled plasma mass spectrometry, and inductively coupled plasma optical emission spectrometry). This review compiles available scientific information on minerals and heavy metals in honey reported from all over the world. To date, 54 chemical elements in various types of honey have been identified and can be divided into 3 groups: major or macroelements (Na, K, Ca, Mg, P, S, Cl), minor or trace elements (Al, Cu, Pb, Zn, Mn, Cd, Tl, Co, Ni, Rb, Ba, Be, Bi, U, V, Fe, Pt, Pd, Te, Hf, Mo, Sn, Sb, La, I, Sm, Tb, Dy, Sd, Th, Pr, Nd, Tm, Yb, Lu, Gd, Ho, Er, Ce, Cr, As, B, Br, Cd, Hg, Se, Sr), and heavy metals (trace elements that have a specific gravity at least 5 times higher than that of water and inorganic sources). Chemical elements in honey samples throughout the world vary in terms of concentrations and are also influenced by environmental pollution.     

Smoking and polyphenols’ addition to improve freshwater mullet (Mugil cephalus) fillets’ quality attributes during refrigerated storage

The combined effects of hot smoking and added quince polyphenol (0.8% and 1.6% v/w) on the quality attributes of mullet (Mugil cephalus) fillets were evaluated. Biochemical parameters that were monitored in the fillets during 75 days of storage (4 ± 1 °C) included trimethylamine (TMA‐N), volatile basic nitrogen (TVB‐N), fatty acids and amino acids. Data were submitted to principal component analysis (PCA) which revealed that the smoking process combined with polyphenols’ treatment was negatively correlated with TVB‐N, TMA‐N, lipids, indices of lipid quality (index of atherogenicity (IA); index of thrombogenicity (IT)) and storage time. Health concern related to the flesh content of polycyclic aromatic hydrocarbons (PAHs) following hot smoking was also evaluated, and analysis showed that the sum of 4 of the PAHs (chrysene, benzo(b)fluoranthene, benz(a)anthracene and BaP) remained far below the maximum limit set by the European Commission. Sensory analysis revealed that the smoked mullet fillet treated with a low dose of polyphenols was a very acceptable new product.     

Effects of Processing on the Compositions and Physicochemical Properties of Fibre Concentrate from Cooked Fruit Pomaces

This study examined the influence of applied technologies namely desugaring, grinding, and bleaching on the compositions (cellulose, hemicelluloses, lignins, and pectins), physicochemical properties (water-holding capacity (WHC), swelling capacity (SWC), oil-holding capacity (OHC)) and the colour of dietary fibre (DF) during the production of fibre concentrates from unusual cooked apple and pear pomaces. Thermogravimetric analysis (TGA) and optical microscopy were also performed to monitor process-induced modification. All the processing conditions affected the compositions and physicochemical properties of DF. The bleaching treatment induced the greatest changes on DF producing yellow cellulose-rich fibre concentrates with improved WHC from 3.2 to 10.0 g/g and improved SWC from 4.0 to 8.8 ml/g. Otherwise, reduction of the particle size influenced hydration properties and colours of DF. WHC and SWC tended to increase with the particle size whereas smaller granulometric size increased the lightness of fibres. Desugaring increased the DF content in both pomaces by 1.2-fold with slight modification of apple insoluble dietary fibre ratio. Fibre concentrates had improved WHC and SWC up to 1.4-fold. All processes had no significant effect (p?<?0.05) on OHC of DF except with ultrafine apple fibre concentrates. Results showed that processing had overall positive effects on DF contents and hydration properties of pomaces from cooked fruits. Bleached fibre concentrates from apple pomace had the highest WHC (10.0 g/g) whereas that of pear had the highest fibre content (89.9 %). Fibres from cooked fruit pomaces may therefore be used as textural ingredients or functional foods.     

Invited review: Characterization of new probiotics from dairy and nondairy products—Insights into acid tolerance,bile metabolism and tolerance,and adhesion capability

The selection of potential probiotic strains that possess the physiological capacity of performing successfully in the gastrointestinal tract (GIT) is a critical challenge. Probiotic microorganisms must tolerate the deleterious effects of various stresses to survive passage and function in the human GIT. Adhesion to the intestinal mucosa is also an important aspect. Recently, numerous studies have been performed concerning the selection and evaluation of novel probiotic microorganisms, mainly probiotic bacteria isolated from dairy and nondairy products. Therefore, it would be crucial to critically review the assessment methods employed to select the potential probiotics. This article aims to review and discuss the recent approaches, methods used for the selection, and outcomes of the evaluation of novel probiotic strains with the main purpose of supporting future probiotic microbial assessment studies. The findings and approaches used for assessing acid tolerance, bile metabolism and tolerance, and adhesion capability are the focus of this review. In addition, probiotic bile deconjugation and bile salt hydrolysis are explored. The selection of a new probiotic strain has mainly been based on the in vitro tolerance of physiologically related stresses including low pH and bile, to ensure that the potential probiotic microorganism can survive the harsh conditions of the GIT. However, the varied experimental conditions used in these studies (different types of media, bile, pH, and incubation time) hamper the comparison of the results of these investigations. Therefore, standardization of experimental conditions for characterizing and selecting probiotics is warranted.     

Production,properties, and some new applications of chitin and its derivatives

Chitin is a polysaccharide composed from N-acetyl-D-glucosamine units. It is the second most abundant biopolymer on Earth and found mainly in invertebrates, insects, marine diatoms, algae, fungi, and yeasts. Recent investigations confirm the suitability of chitin and its derivatives in chemistry, biotechnology, medicine, veterinary, dentistry, agriculture, food processing, environmental protection, and textile production. The development of technologies based on the utilization of chitin derivatives is caused by their polyelectrolite properties, the presence of reactive functional groups, gel-forming ability, high adsorption capacity, biodegradability and bacteriostatic, and fungistatic and antitumour influence. Resources of chitin for industrial processing are crustacean shells and fungal mycelia. Fungi contain also chitosan, the product of N-deacetylation of chitin. Traditionally, chitin is isolated from crustacean shells by demineralization with diluted acid and deproteinization in a hot base solution. Furthermore, chitin is converted to chitosan by deacetylation in concentrated NaOH solution. It causes changes in molecular weight and a degree of deacetylation of the product and degradation of nutritionally valuable proteins. Thus, enzymatic procedures for deproteinization of the shells or mold mycelia and for chitin deacetylation were investigated. These studies show that chitin is resistant to enzymatic deacetylation. However, chitin deacetylated partially by chemical treatment can be processed further by deacetylase. Efficiency of enzymatic deproteinization depends on the source of crustacean offal and the process conditions. Mild enzymatic treatment removes about 90% of the protein and carotenoids from shrimp-processing waste, and the carotenoprotein produced is useful for feed supplementation. In contrast, deproteinization of shrimp shells by Alcalase led to the isolation of chitin containing about 4.5% of protein impurities and recovery of protein hydrolysate.     

Volatile compounds in uninoculated and inoculated table olives with Lactobacillus plantarum (Olea europaea L., cv. Moresca and Kalamata)

Table olives' flavour plays an important role in consumer's acceptability and it depends on various factors such as varieties, intrinsic characteristics, ripening of fruit and processing technologies. Flavour biogenesis is also influenced by addition in brine medium of lactic acid bacteria as inoculants, which reduce spoilage risks and improve sensory characteristics. In this work, flavour profiles of uninoculated and inoculated table olives with Lactobacillus plantarum (cv. Moresca and Kalamata) have been analytically characterised and compared. Twenty-one volatile compounds comprise alcohols, aldehydes, ketones, esters as well as acids formed during Greek-style olive fermentation (3 months brining after) have been characterised by gas chromatography and GC/mass spectrometry. Very high contents of ethanol and appreciable amounts of ethyl acetate, isobutanol, 2-butanone, 1-propanol and 1-hexanol were revealed in all samples with a significant increase in inoculated samples with respect to uninoculated ones. Also 1-butanol, 3-pentanol, 3-hydroxy-2-butanone, cis-3-hexen-1-ol and 2-butanol which were present in lower amounts, disclosed a meaningful increase in inoculated samples of both varieties, especially in Moresca inoculated sample. Acetic acid, isopentanol, 2-pentanol, propyl acetate, ethyl propanoate and 4-penten-1-ol showed a significant increase in inoculated Kalamata sample. These results showed that inoculation of brine medium with lactic acid bacteria starters significantly influenced aroma profiles of both varieties, in particular an increase in concentration of various flavour compounds has been revealed in inoculated table olives.