Optimization of protein recovery from bovine lung by pH shift process using response surface methodology.

BACKGROUND: Response surface methodology (RSM) was used in a sequential manner to optimize solubilization and precipitation conditions in the recovery of protein from bovine lung using pH shift. RESULTS: Separate D-optimal designs were employed for protein solubilization and precipitation. Independent variables investigated for protein solubilization were time (10-120 min), temperature (4-20 °C), pH (8.0-11.0) and solvent/sample ratio (2.5-10). Variables for protein precipitation were time (0-60 min) and pH (4.25-6.00). Soluble protein yields ranged from 323 to 649 g kg-1 and the quadratic model for protein solubilization revealed a coefficient of determination R2 of 0.9958. Optimal conditions for maximum protein solubility were extraction time 140 min, temperature 19 °C, pH 10.8 and solvent/sample ratio 13.02. Protein precipitation yields varied from 407 to 667 g kg-1 , giving a coefficient of determination R2 of 0.9335. Optimal conditions for maximum protein precipitation were pH 5.03 and 60 min. Based on the RSM model, solubilization conditions were manipulated to maximize protein solubilization under reduced water and alkaline usage. These conditions were also validated. CONCLUSION: Models for solubilization and precipitation using bovine and porcine lung were validated; predicted and actual yields were in good agreement, showing cross-species applicability of the results. © 2017 Society of Chemical Industry.

The effects of potato and rice starch as substitutes for phosphate in and degree of comminution on the technological, instrumental and sensory characteristics of restructured ham.

The effects of sodium tripolyphosphate (STPP), two sources of starch (potato starch: PS and rice starch: RS) and comminution degree (CD) on the technological, instrumental and sensory characteristics of reformed hams were studied using response surface methodology. Both starches reduced cook loss and decreased ham flavour intensity, but RS had stronger effects on instrumental measures of texture, while PS was associated with improved juiciness when low/no added STPP was included. Coarsely ground meat, processed 100% with the kidney plate was associated with slightly increased cook loss, reduced texture profile analysis parameters and a more intense ham flavour compared to the other treatment (80% ground with a kidney plate plus 20% with a 9mm plate). STPP was the sole factor affecting overall liking. If starch is included in the formulation, the standard level of STPP (0.3%) can be reduced by half with no increase in cook losses, but some decline in sensory quality cannot be avoided.

The effect of partial-fat substitutions with encapsulated and unencapsulated fish oils on the technological and eating quality of beef burgers over storage.

The effects of fat substitution (≤ 15%) with commercial encapsulated and unencapsulated fish oils on the technological and eating quality of beef burgers over storage [modified atmosphere packs (80% O2:20% CO2); constantly illuminated retail display at 4 °C; for 15 days] were studied using design of experiment (DOE). Burger formulations comprised beef shin (59.5%), salt (0.5%), vitamin E (0.015%) combined with varying levels of beef-fat/fish oils depending on the treatment. Increasing amounts of encapsulated and unencapsulated fish oils in burgers increased polyunsaturated fatty acid content (P < 0.001). Storage decreased (P < 0.001) a* values, which was in agreement with oxymyoglobin data. Vitamin E inclusion in burgers resulted in higher (P < 0.01) oxymyoglobin values. TBARS values increased (P < 0.001) over storage as expected. Fat substitution with unencapsulated oils increased cook loss (P < 0.001) and decreased hardness (P < 0.05) compared to other treatments. Optimisation predicted a burger formulation with 7.8% substitution in beef-fat with encapsulated fish oil. Panellists scored the optimised burger formulation (P < 0.05) lower than controls for overall acceptability.

Modelling the influence of inulin as a fat substitute in comminuted meat products on their physico-chemical characteristics and eating quality using a mixture design approach.

The effects of fat substitution using two commercial inulin products on the physico-chemical properties and eating quality of a comminuted meat product (breakfast sausage) were modelled using a specialised response surface experiment specially developed for mixtures. 17 treatments were assigned representing a different substitution level for fat with inulin. Sausages were formulated to contain pork shoulder, back fat/inulin, water, rusk and seasoning (44.3, 18.7, 27.5, 7 and 2.5% w/w). Composition, sensory, instrumental texture and colour characteristics were assessed. Fructan analysis showed that inulin was unaffected by heat or processing treatments. Models showed increasing inulin inclusions decreased cook loss (p<0.0017) and improved emulsion stability (p<0.0001) but also resulted in greater textural and eating quality modification of sausages. Hardness values increased (p<0.0001) with increasing inulin concentration, with panellists also scoring products containing inulin as less tender (p<0.0112). Optimisation predicted two acceptable sausage formulations with significantly lower fat levels than the control, which would contain sufficient inulin to deliver a prebiotic health effect.

Observations on the water distribution and extractable sugar content in carrot slices after pulsed electric field treatment.

The impact of pulsed electric field (PEF) processing conditions on the distribution of water in carrot tissue and extractability of soluble sugars from carrot slices was studied. Time domain NMR relaxometry was used to investigate the water proton mobility in PEF-treated carrot samples. Three distinct transverse relaxation peaks were observed in untreated carrots. After PEF treatment only two slightly-overlapping peaks were found; these were attributed to water present in the cytoplasm and vacuole of carrot xylem and phloem tissues. This post-treatment observation indicated an increase in water permeability of tissues and/or a loss of integrity in the tonoplast. In general, the stronger the electric field applied, the lower the area representing transverse relaxation (T2) values irrespective of treatment duration. Moreover an increase in sucrose, ß- and α-glucose and fructose concentrations of carrot slice extracts after PEF treatment suggested increases in both cell wall and vacuole permeability as a result of exposure to pulsed electric fields.

Effects of thermal and high hydrostatic pressure processing and storage on the content of polyphenols and some quality attributes of fruit smoothies.

The aim of the present study was the evaluation of high hydrostatic pressure (HHP) processing on the levels of polyphenolic compounds and selected quality attributes of fruit smoothies compared to fresh and mild conventional pasteurization processing. Fruit smoothie samples were thermally (P(70) > 10 min) or HHP processed (450 MPa/1, 3, or 5 min/20 °C) (HHP1, HHP3, and HHP5, respectively). The polyphenolic content, color difference (ΔE), sensory acceptability, and rheological (G'; G''; G*) properties of the smoothies were assessed over a storage period of 30 days at 4 °C. Processing had a significant effect (p < 0.001) on the levels of polyphenolic compounds in smoothies. However, this effect was not consistent for all compound types. HHP processed samples (HHP1 and HHP3) had higher (p < 0.001) levels of phenolic compounds, for example, procyanidin B1 and hesperidin, than HHP5 samples. Levels of flavanones and hydroxycinnamic acid compounds decreased (p < 0.001) after 30 days of storage at 2-4 °C). Decreases were particularly notable between days 10 and 20 (hesperidin) and days 20 and 30 (chlorogenic acid) (p < 0.001). There was a wide variation in ΔE values recorded over the 30 day storage period (p < 0.001), with fresh and thermally processed smoothies exhibiting lower color change than their HHP counterparts (p < 0.001). No effect was observed for the type of process on complex modulus (G*) data, but all smoothies became less rigid during the storage period (p < 0.001). Despite minor product deterioration during storage (p < 0.001), sensory acceptability scores showed no preference for either fresh or processed (thermal/HHP) smoothies, which were deemed acceptable (>3) by panelists.