Improvement in Texture of Pressure-Assisted Thermally Processed Carrots by Combined Pretreatment using Response Surface Methodology

Application of high-pressure assisted thermal processing (PATP) at pilot scale for replacing conventional maturation and thermal cooking in whiteleg shrimp (Litopenaeus vannamei)

BACKGROUND

The aim of this work was to examine for the first time the use of high-pressure assisted thermal processing (PATP) (100, 350, 600 MPa; 100 °C; 3 min) at pilot scale for replacing shrimp (Litopenaeus vannamei) maturation and cooking, analyzing its impact on peeling yield, color, texture and sensory properties. Shrimps subjected to conventional maturation (ice; 2 days) and thermal cooking (100 °C; boiling water, 3 min) were used as controls.

RESULTS

PATP treatments at 100-350 MPa improved manual peelability over the control (P ≤ 0.05), maintaining similar peeling yield, color (L*, a*, b*), texture (shear force, shear work) and sensory properties (appearance before and after peeling, flavor, firmness; P < 0.05). However, increasing pressure to 600 MPa clearly overprocessed the samples, making it impossible to remove all the meat from the shell and resulting in a softer texture, 4.1% lower peeling yield and worse sensory quality (P ≤ 0.05).

CONCLUSION

PATP (< 350 MPa; 100 °C) could be an alternative to replace conventional maturation and thermal cooking in the production of cooked shrimps, reducing processing time from days to minutes by performing both processes in a single step. © 2022 Society of Chemical Industry.

Effects of Elevated Hydrostatic Pressure against Mesophilic Background Microflora and Habituated Salmonella Serovars in Orange Juice

With recent improvements in the commercial feasibility of high pressure pasteurization units, the technology is gaining rapid acceptability across various sectors of food manufacturing, thus requiring extensive validation studies for effective adoption. Various times (1 min to 10 min) and intensity levels (0 MPa to 380 MPa) of elevated hydrostatic pressure were investigated for decontamination of mesophilic background microflora and inoculated Salmonella in orange juice. Results were analyzed by GLM procedure of SAS using Tukey- and Dunnett-adjusted ANOVA, additionally the K_max and D-values were calculated using best-fitted (maximum R²) model obtained by GInaFit software. At 380 MPa, for treatments of 1 min to 10 min, D-value of 1.35, and inactivation K_max of 3.34 were observed for Salmonella serovars. D-values were 5.90 and 14.68 for treatments of 241 MPa and 103 MPa, respectively. Up to 1.01 and >7.22 log CFU/mL reductions (p < 0.05) of habituated Salmonella serovars at planktonic stages were achieved using application of pressure at 380 MPa for 1 min and 10 min, respectively. Mesophilic background microflora counts were reduced (p < 0.05) by 1.68 to 5.29 log CFU/mL after treatment at 380 MPa for 1 min and 10 min, respectively. Treatments below two minutes were less efficacious (p ≥ 0.05) against the pathogen and background microflora, in vast majority of time and pressure combinations.

Emerging technique for healthier frying for production of reduced-fat beetroot (Beta vulgaris) chips

In the present work, the processing variables were optimized to retain betalain compound and their effect on quality attributes (oil content, breaking force and color) of fried beetroot chips. The beetroot slices were fried in lab scale vacuum fryer. Experimental design with temperature (86-153 °C), absolute pressure (1.3-9.7 kPa) and frying time (2.6-9.4 min) as independent variables which produced 20 different combinations, were studied using response surface methodology to study the effect of these variables on product responses. Multiple regression equations were obtained to describe the effects of each variable on product responses. Results predicted that optimum frying conditions namely temperature ranging from 101 to 110 °C, pressure ranging from 2.9 to 4.4 kPa and time 6.0 min required for preparing beetroot chips with oil content (Y₁) ≤ 15.7, breaking force (Y₂) ≤ 11.53, L* value (Y₃) ≥ 27.94, a* value (Y₄) ≤ 17.87, b* value (Y₅) ≥ 6.46, betalain content (Y₆) ≥ 13.05 (mg/l) and overall acceptability (Y₇) ≥ 7.5. Further results showed that traditionally fried beetroot chips contain 2.6 mg/l betalain, 19.68 N breaking force, 21.1 L*, 15.18 a*, 2.38 b*, overall acceptability 6.0 and 38.41 % oil content.

Optimization of process parameters for gelatin extraction from the skin of Blackspotted croaker using response surface methodology

Utilization of waste from fish processing industry for production of value added products has attracted substantial attention. Blackspotted croaker (Protonibea diacanthus) is a marine fish having the potential of abundant supply of raw skins for production of gelatin. This study was aimed to optimize the extraction conditions for gelatin production from skin of Blackspotted croaker. Response surface methodology (RSM) was adopted by following central composite design to determine the optimal conditions of four independent variables namely concentration of NaOH (X1), soaking time (X2), extraction temperature (X3) and extraction time (X4) for three response variables namely yield, gel strength and melting point. The models obtained by RSM produced a satisfactory fit to the data with respect to gelatin extraction (for gelatin yield, R (2)  = 0.867, P = 0.0003; for gel strength, R (2)  = 0.837, P = 0.007; for melting point, R (2)  = 0.765, P = 0.01). Based on these models, the optimum conditions to achieve the predicted maximum values were: yield of 17.21 % at X1 = 0.23 %, X2 = 46.19 min, X3 = 55.29 °C and X4 = 17.29 h; gel strength of 422.69 g at X1 = 0.22 %, X2 = 44.56 min, X3 = 59.02 °C and X4 = 15.35 h and melting point of 23.48 °C at X1 = 0.20 %, X2 = 46.68 min, X3 = 56.23 °C and X4 = 15.21 h. It can be concluded from the present study that Blackspotted croaker skin is a prospective source to produce gelatin in good yield with desirable quality attributes comparable to commercially available mammalian gelatins.

Optimization of media components for chitinase production by chickpea rhizosphere associated Lysinibacillus fusiformis B-CM18

Chitinase producing strain B-CM18 was isolated from chickpea rhizosphere and identified as Lysinibacillus fusiformis B-CM18. It showed in vitro antifungal activity against a wide range of fungal plant pathogens and was found to produce several PGPR activities. Further, a multivariate response surface methodology was used to evaluate the effects of different factors on chitinolytic activity and optimizing enzyme production. A central composite design was employed to achieve the highest chitinase production at optimum values of the process variables, viz., temperature (20-45 °C), sodium chloride (2-7%), starch (0.1-1%) and yeast extract (0.1-1%), added in the minimal medium supplemented with colloidal chitin (1-10%; w:w). The fit of the model (R(2)  = 0.5692) was found to be significant. The production medium to achieve the highest chitinase production (101 U ml(-1) ) was composed of the minimal medium composed of chitin (6.09%), NaCl (4.5%), starch (0.55%) and yeast extract (0.55%) with temperature (32.5 °C). The results show that the optimization strategy led to an increase in chitinase production by 56.1-fold. The molecular mass of the chitinase was estimated to be 20 kDa by anion exchange and gel filtration chromatography. Further, purified chitinase showed strong antifungal activity against test pathogens. Overall, these results may serve as a base line data for enhancing the chitinolytic potential of bacterial antagonists for bio-management of chickpea pathogens.

Combined effects of high-pressure and enzymatic treatments on the hydrolysis of chickpea protein isolates and antioxidant activity of the hydrolysates

A chickpea protein isolate (CPI) was pretreated before hydrolysis under a pressure that varied between 100 and 600MPa. The hydrolysis rate increased significantly with pressure above 300MPa. At 40min, the DH of the control was 15.3%, while the DH of the CPI treated at 300MPa was 18.5%, which reached 23.74% post treatment at 400MPa. The pretreatment of CPI above 300MPa enhanced the superoxide anion capturing rate of enzymatic hydrolysis. Pretreatment at 400MPa significantly reduced the hydrolysis time with the release of antioxidant peptides. While hydrolysis by Alcalase during treatment at high pressure (100-300MPa) significantly increased the degree of hydrolysis (DH), its maximum value peaked after hydrolysis at 200MPa for 30min. In addition, hydrolysates obtained at high pressure (100-300MPa) had a higher superoxide anion capturing rate. High-pressure treatment at 200MPa for 20min resulted in products with high antioxidative activity. The molecular-weight (MW) determination of the enzymatic hydrolysates indicated that hydrolysis at high pressure could significantly increase the amount of low-molecular-weight peptides.