Heat stress affects some physiological and productive variables and alters metabolism in dairy ewes

Heat stress (HS) has a significant economic impact on the global dairy industry. However, the mechanisms by which HS negatively affects metabolism and milk synthesis in dairy ewes are not well defined. This study evaluated the production and metabolic variables in dairy ewes under controlled HS conditions. Eight Lacaune ewes (75.5 ± 3.2 kg of body weight; 165 ± 4 d of lactation; 2.31 ± 0.04 kg of milk per day) were submitted to thermoneutral (TN) or HS conditions in a crossover design (2 periods, 21 d each, 6-d transition). Conditions (day-night, 12–12 h; relative humidity; temperature-humidity index, THI) were: TN (15–20°C; 50 ± 5%; THI = 59–65) and HS (28–35°C; 45 ± 5%; THI = 75–83). Ewes were fed ad libitum and milked twice daily. Rectal temperature, respiratory rate, feed intake, water consumption, and milk yield were recorded daily. Milk and blood samples were collected weekly. Additionally, TN and HS ewes were exposed to glucose tolerance test, insulin tolerance test, and epinephrine challenge. Heat stress reduced feed intake (?11%), and increased rectal temperature (+0.77°C), respiratory rate (+90 breaths/min), and water consumption (+28%). Despite the reduced feed intake, HS ewes produced similar milk to TN ewes, but their milk contained lower fat (?1.7 points) and protein (?0.86 points). Further, HS milk tended to contain more somatic cells (+0.23 log points). Blood creatinine was greater in HS compared with TN, but no differences in blood glucose, nonesterified fatty acids, or urea were detected. When glucose was infused, TN and HS had similar insulin response, but higher glucose response (+85%) was detected in HS ewes. Epinephrine infusion resulted in lower nonesterified fatty acids response (?215%) in HS than TN ewes. Overall, HS decreased feed intake, but milk production was not affected. Heat stress caused metabolic adaptations that included increased body muscle degradation and reduced adipose tissue mobilization. These adaptations allowed ewes to spare glucose and to avoid reductions in milk yield.     

Dielectric properties of Indian Basmati rice flour slurry

Dielectric properties of Indian Basmati rice samples (dry ground flour and wet aqueous slurry) were measured over the frequency range 500–2500 MHz. Temperature dependence of dielectric properties of rice flour slurries (20, 30 and 50 g flour per 100 g water yielding approximately 1:5, 1:3 and 1:2 flour to water ratio) were studied between 30 and 80 °C. Results indicated that dielectric constants (ε′) generally did not vary with frequency while the loss factor (ε″) showed an increasing trend. A sharp change in dielectric parameters were noted above 70 °C attributable to rice starch gelatinization, an observation confirmed later by differential scanning calorimetry. An increase in flour slurry concentration systematically reduced ε′ during the entire frequency range while variations in ε″ values were mixed. Addition of 1% salt markedly increased ε″ of slurries whereas butter resulted in significant reduction in ε′ values. Rice flour slurry containing both salt and butter exhibited intermediate values of dielectric properties. Both ε′ and ε″ data of rice slurries generally fitted a 2nd order polynomial relationship with temperature. These results suggest that dielectric measurements could be used to study frequency, concentration, ingredient and temperature dependent changes in starch–water systems during heating.     

Biochemical studies on proteins from cheese whey and blood plasma by-products

Efforts have been done to recover proteins from waste liquors rich in protein in a soluble form. Cheese whey and animal bloods are byproducts from the manufacture of cheese and meat. It contains a variety of proteins which can be reclaimed. The efficiency of protein precipitation from the sweet-cheese whey by the use of hydroxyethyl cellulose (HEC) was similar to that precipitated by the use of carboxymethyl cellulose (CMC). Both are greater than that precipitated by trichloro acetic acid. The same results of the efficiency of precipitation were attained when the plasma protein was precipitated. It was found that cheesewhey protein-HEC-complex and plasms protein-HEC-complex contain a large amount of essential amino acids. Electrophoretic separation of whey protein complex showed that β-Lactoglobulin forms the major fraction while in case of plasma protein complex albumin forms the major fraction. The fractionation patterns of different complexes with HEC, CMC or TCA gave the same components and about the same ratio. It appears from these results that HEC-protein complexes are preferable than CMC-protein complexes or proteins precipitated by TCA. Chemical analysis of whey protein complexes revealed that lactose content of whey protein-HEC-complex was higher than that of CMC-complex or protein precipitated by TCA. Elemental analysis of protein complexes showed that the level of sodium, phosphorus, and potassium was increased while that of copper or zinc decreased. Cellulose derivative protein complexes showed no significant effects on the liver or kindney function of albino rat and these results indicated that no toxic effect was observed from the uses of these protein complexes in feeding.     

Rheological characteristics of tamarind (Tamarindus indica L.) juice concentrates

The steady-shear and small-amplitude oscillatory rheological properties of tamarind (Tamarindus indica L.) juice concentrate (TJC) were studied in the temperature range of 10-90 °C using a controlled-stress rheometer. Under steady-shear deformation tests, shear stress-shear rate data were adequately fitted to the Herschel-Bulkley and Casson model at lower (10-30 °C) and higher (50−90 °C) temperature range, respectively. The Carreau model was applied to describe the shear-thinning behaviour of the concentrate, and the model parameters estimated empirically showed temperature dependence. Oscillatory shear data of TJC revealed predominating viscous behaviour (G″>G′) at lower frequency range while the elastic modulus predominating over the viscous one (G′>G″) at higher frequency range. The Cox-Merz rule that relates steady shear and dynamic material functions was tested and not followed by most of the temperatures. The specific heat of TJC increased with temperature and the glass transition temperature of the product was found to be −70.74 °C.     

Antioxidant abietane diterpenoids from Salvia barrelieri

The root extract of endemic Algerian Salvia species Salvia barrelieri Ettling and its diterpenoids were investigated for potential antioxidant activity. From its acetone extract, a new natural abietane diterpenoid 7-oxoroyleanone-12-methyl ether (1) and six known diterpenoids 7α-acetoxyroyleanone-12-methyl ether (2), royleanone (3), horminone (4), 7-acetylhorminone (5), cryptojaponol (6) and inuroyleanol (7) were isolated, and their structures were elucidated by spectroscopic means. Among the diterpenoids, the new diterpenoid 7-oxoroyleanone-12-methyl ether (1) showed highest superoxide anion scavenging activity while inuroyleanol (7) showed both the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity and inhibition of lipid peroxidation in β-carotene–linoleic acid system. These findings indicate that S. barrelieri extract as well as isolated abietane diterpenes, particularly inuroyleanol are promising antioxidants which can be used as food additives.     

Extraction,optimisation and characterisation of phenolics from Thymus vulgaris L.: phenolic content and profiles in relation to antioxidant,antidiabetic and antihypertensive properties

The objectives of this study were to examine varying extraction conditions of Thymus vulgaris L. as related to phenolic content and profiles of the extracts and their antioxidant, antihypertensive and antidiabetic properties. Phenolics were extracted under various conditions pertaining to free and bound phenolics, solvent type and combination of extraction time and temperature, and these extracts were evaluated in terms of their antioxidant activities and inhibitory activities of angiotensin‐converting enzyme (ACE), α‐glucosidase and α‐amylase. The acetone–water solvent mixture (1:1; v/v) produced the extract with the greatest phenolic content, antioxidant activity and inhibitory activities of ACE and α‐glucosidase. The optimal extraction temperature for maximum phenolic content and antioxidant activity associated with methanol extraction was 60 °C, whereas a lower temperature at 40 °C was required to maximise inhibitory activities for ACE, α‐glucosidase and α‐amylase. An inverse relationship was seen between antioxidant and glucosidase inhibitory activities vs. the ACE and α‐amylase inhibitory activities, which suggests the need for extractions to be directed to specific bioactivities of thyme extracts. Generally, the results indicate major differences in phenolic profiles among the tested extraction conditions with thymol as the predominant phenolic seen in most extractions, while gallic acid, rosmarinic acid or diosmin also predominated in other extracts. Extracts with the same predominant phenolic compound and similar phenolic content showed major disparities in their ACE, glucosidase and α‐amylase inhibitory activities, indicating that the major phenolic profiles of thyme extracts may not be necessarily related to the degree of inhibition of ACE, glucosidase and α‐amylase enzymes.     

Effects of radiation process on total protein and amino acids composition of raw and processed pearl millet flour during storage

The present work describes radiation‐induced effects during storage on total protein and amino acids composition of raw and processed flour of two pearl millet cultivars (Ashana and Dembi). The protein content of the whole raw flour was 14.46% and 13.38% for Ashana and Dembi cultivars, respectively. Dehulling of the grains reduced the protein content to 13.38% and 12.67% for the cultivars, respectively. Storage of the radiated whole and dehulled flour for 60 days slightly reduced the protein content even after cooking. The effect of radiation process in combination with the treatments applied to the grains and/or flour on amino acids contents was found to be varying between the cultivars. Most of the amino acids were stable against all treatments except leucine, glutamic acid and phenylalanine. Regardless of the storage period and processing method, amino acid contents of Ashana cultivar were increased after radiation process compared to that of Dembi cultivar.     

Dietary fibre components,antioxidant activities and hydration properties of ripe persimmon (Diospyros kaki L. cv. Daebong) peel powders as affected by different washing treatments

Dietary fibre components, hydration properties and antioxidant activities such as 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, reducing power, metal chelating and 2,2′‐azino‐bis,3‐ethyl‐benzo‐thiazoline‐6‐sulphonic acid (ABTS) radical scavenging activities of persimmon peel powders using different washing treatments (tap water at 20 °C and hot water) were investigated. Peel powder obtained from hot water‐washed peels (74.95 g per 100 g) had higher dietary fibre content than tap water‐washed (65.50 g per 100 g) and unwashed (60.99 g per 100 g) peels. The higher content of total phenolic and ascorbic acid were found in peel powder obtained from unwashed peels, whereas washed peels had more β‐carotene content. The EC₅₀ values of scavenging DPPH and ABTS radical for peel powders obtained from unwashed, tap water‐washed and hot water‐washed peels were 75.44, 142.18 and 110.17 μg mL^?1 respectively and 5.31, 5.34 and 5.39 μg mL^?1 respectively. Therefore, hot water washing is recommended to obtain better quality products from persimmon peel for use as a fibre supplement.     

Encapsulation by spray drying of bioactive components, physicochemical and morphological properties from purple sweet potato

Purple-fleshed sweet potato flour could be used to enhance the colour, flavour and nutrients in food products. Thus, the investigation was to produce encapsulated flours from purple-fleshed sweet potato by spray drying using combinations of various levels of ascorbic acid (5 g kg⁻¹ and 10 g kg⁻¹) and maltodextrin (30 g kg⁻¹ and 100 g kg⁻¹) and to evaluate their effects on bioactive components, physicochemical and morphological properties. Encapsulated flours had higher total phenolic content, antioxidant capacity and water solubility index than non-encapsulated flour. There were no significant differences in anthocyanin content between encapsulated and non-encapsulated flours. However, water absorption index and flavonoids content of encapsulated flours depended on concentrations of ascorbic acid and maltodextrin. In addition, the high concentrations of ascorbic acid and maltodextrin encapsulated flours had higher glass transition temperature as compared to that of lower concentrations. In respect to morphology, the particles of encapsulated flours with high concentration of ascorbic acid and maltodextrin were more aggregated than those encapsulated with lower concentrations. Therefore, flours encapsulated with 10 g kg⁻¹ ascorbic acid and 30 g kg⁻¹ maltodextrin could be used to enhance the antioxidant activities of functional food ingredients.     

Purification and identification of novel antioxidant peptides from enzymatic hydrolysates of sardinelle (Sardinellaaurita) by-products proteins

In order to utilise sardinelle (Sardinellaaurita) protein by-products, which is normally discarded as industrial waste in the process of fish manufacturing, heads and viscera proteins were hydrolysed by different proteases to obtain antioxidative peptides. All hydrolysates showed different degrees of hydrolysis and varying degrees of antioxidant activities. Hydrolysate generated with crude enzyme extract from sardine (Sardinapilchardus) displayed high antioxidant activity, and the higher DPPH radical-scavenging activity (87 ± 2.1% at 2 mg/ml) was obtained with a degree of hydrolysis of 6%. This hydrolysate was fractionated by size exclusion chromatography on a Sephadex G-25 into eight major fractions (P₁–P₈). Fraction P₄, which exhibited the highest DPPH scavenging activity, was then fractionated by reversed-phase high performance liquid chromatography (RP-HPLC). Seven antioxidant peptides were isolated. The molecular masses and amino acids sequences of the purified peptides were determined using ESI-MS and ESI-MS/MS, respectively. Their structures were identified as Leu-His-Tyr, Leu-Ala-Arg-Leu, Gly-Gly-Glu, Gly-Ala-His, Gly-Ala-Trp-Ala, Pro-His-Tyr-Leu and Gly-Ala-Leu-Ala-Ala-His. The first peptide displayed the highest DPPH radical-scavenging activity (63 ± 1.57%; at 150 μg/ml) among these peptides.