Effect of spray drying on the sensory and physical properties of hydrolysed casein using gum arabic as the carrier.

This study was aimed at spray drying hydrolysed casein using gum Arabic as the carrier agent, in order to decrease the bitter taste. Three formulations with differing proportions of hydrolysed casein: gum Arabic (10:90, 20:80 and 30:70) were prepared and characterized. They were evaluated for their moisture content, water activity, hygroscopicity, dispersibility in water and in oil, particle size and distribution, particle morphology, thermal behaviour (DSC) and bitter taste by a trained sensory panel using a paired-comparison test (free samples vs. spray dried samples). The proportion of hydrolysed casein did not affect the morphology of the microspheres. The spray drying process increased product stability and modified the dissolution time, but had no effect on the ability of the material to dissolve in either water or oil. The sensory tests showed that the spray drying process using gum Arabic as the carrier was efficient in attenuating or masking the bitter taste of the hydrolysed casein.

Antioxidant capacity of flaxseed products: the effect of in vitro digestion.

This study evaluated the effect of in vitro digestion of flaxseed products on Folin-Ciocalteu reagent reducing substances (FCRRS), its antioxidant capacity and prevention of oxidative DNA damage in human monocyte cell line U937. Flaxseed protein isolate was obtained from defatted flaxseed meal and the protein hydrolysate with high antioxidant capacity was obtained from hydrolysis of the protein isolate with Alcalase in a two factor central composite rotatable design (pH 8.5 and enzyme: substrate 1:90, w/w). The FCRRS content and antioxidant capacity measured by FRAP and ORAC in aqueous and 70 % methanol extracts were the highest in protein hydrolysate, followed by protein isolate, while the defatted meal showed the lowest values. After in vitro gastrointestinal digestion, the FCRRS content of protein isolate and hydrolysate reached similar values, however the hydrolysate had the highest antioxidant capacity, measured by FRAP while the isolate had the highest ORAC values. The defatted meal showed the lowest capacity in all assays (p < 0.05). The hydrolysate did not protect against DNA damage induced by H2O2 in U937 cells under the conditions of the present study. The results suggest that flaxseed protein isolate and hydrolysate are potential functional food ingredients with antioxidant capacity.

Effect of addition of CO2 to raw milk on quality of UHT-treated milk.

The objective of this study was to evaluate the effect of addition of CO(2) to raw milk on UHT milk quality during storage. Control milk (without CO(2) addition) and treated milk (with CO(2) addition up to pH 6.2) were stored in bulk tanks at 4°C for 6d. After storage, both samples were UHT processed using indirect heating (140°C for 5s). Samples were aseptically packed in low-density polyethylene pouches and stored in the dark at room temperature. Raw milk was evaluated upon receipt for physicochemical composition, proteolysis, lipolysis, standard plate count, psychrotrophic bacteria, and Pseudomonas spp. counts, and after 6d of storage for proteolysis, lipolysis, and microbial counts. After processing, UHT milk samples were evaluated for physicochemical composition, proteolysis, and lipolysis. Samples were evaluated for proteolysis and lipolysis twice a month until 120d. Peptides from pH 4.6-soluble N filtrates were performed by reversed-phase HPLC after 1 and 120d of storage. A split-plot design was used and the complete experiment was carried out in triplicate. The results were evaluated by ANOVA and Tukey's test. After 6d of storage, CO(2)-treated raw milk kept its physicochemical and microbiological quality, whereas the untreated milk showed significant quality losses. A significant increase in proteolysis occurred during 120d of storage in both treatments, but the increase occurred 1.4 times faster in untreated UHT milk than in CO(2)-treated UHT milk. In both UHT milks, the proteolysis was a consequence of the action of plasmin and microbial proteases. However, the untreated UHT milk showed higher microbial protease activity than the treated UHT milk. The addition of CO(2) to the raw milk maintained the quality during storage, resulting in UHT milk with less proteolysis and possibly longer shelf life, which is usually limited by age gelation of UHT milk.

Characterization and ACE-inhibitory activity of amaranth proteins.

Amaranth seeds have been considered as an excellent alternative or complementary source of food protein due to their balanced amino acid composition. However, their potential as a source of bioactive peptides has not been explored. The present study is aimed at characterizing and evaluating the activity of the angiotensin converting enzyme inhibitor of the amaranth protein concentrate and of hydrolysates produced with Alcalase. The protein concentrate, after simulated gastrointestinal digestion, showed lower angiotensin converting enzyme-inhibitory activity (IC(50) of 0.439 +/- 0.018 mg protein/mL and 0.475 +/- 0.021 mg protein/mL, for untreated and heat treated protein concentrate, respectively) than the hydrolysates produced with Alcalase, before and after simulated gastrointestinal digestion (IC(50) 0.118 +/- 0.009, 0.123 +/- 0.007, 0.137 +/- 0.002, and 0.176 +/- 0.014 mg protein/mL, respectively). The simulated gastrointestinal digestion (pepsin-pancreatin) did not significantly alter the angiotensin-converting enzyme inhibiting activity of the Alcalase hydrolysates, suggesting that the peptides of the hydrolysates were resistant to gastrointestinal hydrolysis. These results highlight the angiotensin converting enzyme-inhibitory potential of amaranth proteins, which is an indication of their health-promoting potential.

Effect of intraperitoneally administered hydrolyzed whey protein on blood pressure and renal sodium handling in awake spontaneously hypertensive rats

The present study evaluated the acute effect of the intraperitoneal (ip) administration of a whey protein hydrolysate (WPH) on systolic arterial blood pressure (SBP) and renal sodium handling by conscious spontaneously hypertensive rats (SHR). The ip administration of WPH in a volume of 1 ml dose-dependently lowered the SBP in SHR 2 h after administration at doses of 0.5 g/kg (0.15 M NaCl: 188.5 ± 9.3 mmHg vs WPH: 176.6 ± 4.9 mmHg, N = 8, P = 0.001) and 1.0 g/kg (0.15 M NaCl: 188.5 ± 9.3 mmHg vs WPH: 163.8 ± 5.9 mmHg, N = 8, P = 0.0018). Creatinine clearance decreased significantly (P = 0.0084) in the WPH-treated group (326 ± 67 æL min-1 100 g body weight-1) compared to 0.15 M NaCl-treated (890 ± 26 æL min-1 100 g body weight-1) and captopril-treated (903 ± 72 æL min-1 100 g body weight-1) rats. The ip administration of 1.0 g WPH/kg also decreased fractional sodium excretion to 0.021 ± 0.019 percent compared to 0.126 ± 0.041 and 0.66 ± 0.015 percent in 0.15 M NaCl and captopril-treated rats, respectively (P = 0.033). Similarly, the fractional potassium excretion in WPH-treated rats (0.25 ± 0.05 percent) was significantly lower (P = 0.0063) than in control (0.91 ± 0.15 percent) and captopril-treated rats (1.24 ± 0.30 percent), respectively. The present study shows a decreased SBP in SHR after the administration of WPH associated with a rise in tubule sodium reabsorption despite an angiotensin I-converting enzyme (ACE)-inhibiting in vitro activity (IC50 = 0.68 mg/mL). The present findings suggest a pathway involving ACE inhibition but measurements of plasma ACE activity and angiotensin II levels are needed to support this suggestion.

Effect of intraperitoneally administered hydrolyzed whey protein on blood pressure and renal sodium handling in awake spontaneously hypertensive rats.

The present study evaluated the acute effect of the intraperitoneal (ip) administration of a whey protein hydrolysate (WPH) on systolic arterial blood pressure (SBP) and renal sodium handling by conscious spontaneously hypertensive rats (SHR). The ip administration of WPH in a volume of 1 ml dose-dependently lowered the SBP in SHR 2 h after administration at doses of 0.5 g/kg (0.15 M NaCl: 188.5 +/- 9.3 mmHg vs WPH: 176.6 +/- 4.9 mmHg, N = 8, P = 0.001) and 1.0 g/kg (0.15 M NaCl: 188.5 +/- 9.3 mmHg vs WPH: 163.8 +/- 5.9 mmHg, N = 8, P = 0.0018). Creatinine clearance decreased significantly (P = 0.0084) in the WPH-treated group (326 +/- 67 microL min-1 100 g body weight-1) compared to 0.15 M NaCl-treated (890 +/- 26 microL min-1 100 g body weight-1) and captopril-treated (903 +/- 72 microL min-1 100 g body weight-1) rats. The ip administration of 1.0 g WPH/kg also decreased fractional sodium excretion to 0.021 +/- 0.019% compared to 0.126 +/- 0.041 and 0.66 +/- 0.015% in 0.15 M NaCl and captopril-treated rats, respectively (P = 0.033). Similarly, the fractional potassium excretion in WPH-treated rats (0.25 +/- 0.05%) was significantly lower (P = 0.0063) than in control (0.91 +/- 0.15%) and captopril-treated rats (1.24 +/- 0.30%), respectively. The present study shows a decreased SBP in SHR after the administration of WPH associated with a rise in tubule sodium reabsorption despite an angiotensin I-converting enzyme (ACE)-inhibiting in vitro activity (IC50 = 0.68 mg/mL). The present findings suggest a pathway involving ACE inhibition but measurements of plasma ACE activity and angiotensin II levels are needed to support this suggestion.

Preservation of beta-carotene from carrots.

Beta-carotene acts as a pro-vitamin A or anti-cancer compound. Carrots contain the highest amount of beta-carotene of common fruits and vegetables, but each year 25% of carrot production is lost in the U.S. during processing and storage, while, at the same time, the market demand increases. This article is a review of the most recent studies concerning beta-carotene retention in carrots during processing and storage. Reducing the water activity by adding some aw lowering ingredients results in poor shelf-life. Drying or freezing gives better retention during storage than reducing the water activity, if the process is well controlled. Canning or freeze-drying were shown to be more effective. The trans form of beta-carotene in carrots is replaced by the cis form during processing. Beta-Carotene can be extracted from carrots, but the half-life of free beta-carotene is reduced to 2 d in the juice extract at room temperature. By encapsulation methods,the half-life can be increased by 6 months.