The effectiveness of ozone and acidulant treatments in extending the refrigerated shelf life of fresh-cut potatoes

Abstract: The objective of the study was to determine the effectiveness of acidulant dip treatments (with or without aqueous ozone) to reduce enzymatic browning and to extend the shelf life of fresh‐cut potato slices during refrigerated storage (4 °C) for 28 d. Potato slices subjected to aqueous ozone (2 ppm) had significantly (P≤ 0.05) higher L‐values and lower a‐values, but ozone did not appear to have any effect on aerobic plate counts (APCs) or polyphenol oxidase (PPO) activity. NatureSeal (NS) and sodium acid sulfate (SAS) were the most effective acidulant treatments in reducing browning (significantly [P≤ 0.05] higher L‐values, lower a‐values, and browning index values) regardless of ozone treatment. NS and SAS also had lower PPO activity compared to other treatments on days 0 and 28, and significantly (P≤ 0.05) lower APCs (≤2.00 log CFU/g) over refrigerated storage. Therefore, the SAS treatment was comparable to NS, a commercially available product, and showed promise as an effective antibrowning dip to reduce browning and spoilage in fresh‐cut potato products. Practical Application: A 1% SAS dip treatment which included 1% citric and 1% ascorbic acid was found to be an effective antibrowning dip for fresh‐cut potatoes along with NatureSeal®'s PS‐10, compared to other treatments. They were both effective in maintaining low microbial counts over refrigerated storage. Additionally, aqueous ozone washes (2 ppm) showed significant benefits to reduce browning; however, ozone did not affect microbial counts or PPO enzyme activity. Therefore, the SAS treatment could have potential use in the fruit and vegetable industry to reduce browning and spoilage in fresh‐cut potato products.     

The Effectiveness of Antibrowning Dip Treatments to Reduce After‐Cooking Darkening in Potatoes

Abstract: After‐cooking darkening (ACD) is an inherent and undesirable trait that develops in cooked potatoes. The objective of this study was to evaluate the effectiveness of sodium acid sulfate (SAS) dip treatments compared to other antigraying treatments and a control to reduce ACD in boiled, Katahdin potatoes. Dip treatments were applied for 3 min prior to boiling and included: 3% SAS, 3% citric acid (CA), 3% sodium acid pyrophosphate (SAPP), along with a distilled water control. SAS‐ and CA‐treated potatoes had slightly, but significantly (P ≤ 0.05) higher b* and chroma values, which indicates a more intense yellow potato color, with less graying, compared to the control. SAS‐ and CA‐treated potatoes also had significantly (P≤ 0.001) lower pH values for inner and outer potato surfaces than the control. No significant (P > 0.05) differences were detected for total phenolic or mineral contents among treatments. CA and SAPP samples had slightly, but significantly (P≤ 0.05) higher moisture contents than the control. Sensory test results showed no significant differences for color, aftertaste, or overall acceptability. However, CA‐treated samples were rated significantly (P≤ 0.05) lower for flavor than all other treatments and panelists commented on sour notes. CA‐ and SAS‐treated potatoes were scored slightly, but significantly lower for texture than other treatments due to a waxy outer layer. However, SAS was the most acidic dip treatment, but did not significantly affect flavor. Overall, results suggest that SAS was similarly accepted by consumers in comparison to CA and SAPP, which is the industry standard to reduce ACD. Practical Application: After‐cooking darkening (ACD) is an undesirable potato trait that occurs after potatoes have been processed. Sodium acid pyrophosphate (SAPP) has been used as the industry standard to reduce ACD. Sodium acid sulfate (SAS) treatments prior to boiling appeared to be comparable to SAPP and citric acid in effectiveness to reduce ACD. SAS did not negatively affect the flavor of boiled potato samples according to sensory results. The SAS treatment may be more beneficial for potatoes intended for potato salad products.     

Effect of the homogenization process on the sensory and rheological properties in model system

High pressure homogenization has been used for preparation and stabilization of emulsions and suspensions, promoting physical changes in products, such as viscosity change. However, its use in model systems for fruit nectar is innovative. This study aimed to evaluate the effect of the processing in high pressure homogenizer on the rheological behavior and the sensory attributes in model system of gellan gum. Gellan gum (0.05%), organic acids (0.3%), and sucrose (10%) were used to prepare the solutions, which were subsequently homogenized (0—control, 25 and 50 MPa) at 25°C. Rheological and sensory analyses were performed. The samples presented pseudoplastic behavior without residual stress and were characterized by the Ostwald-de-Waele model. The homogenization pressure (P_H) altered the viscosity of the model systems, reduced the consistency index and apparent viscosity, and increased the flow behavior index. The stimuli sour taste and viscosity differed among the parameters evaluated in the time-intensity analysis. No differences were observed for the maximum intensity of viscosity between the treated samples (25 and 50 MPa), which exhibited a similar temporal profile. Therefore, studies on the rheological and sensory behavior are fundamental to product development and process optimization. The present study shows new trends on the use of the high pressure homogenizer and the sensory profile in model systems that can be used for fruit nectar. This study evaluated the sensory attributes through the time-intensity analysis. The sensory data indicate that the homogenization pressure altered the viscosity perception, but did not alter the perception of the acid taste for the same organic acid used. Sensory as well as rheological data present new alternatives for product development. These findings are interesting for future research, equipment design, and process optimization.     

The influence of acidulants and oils on autosterilization of home-made mayonnaise

The rate of autosterilization of mayonnaise inoculated deliberately with salmonellas is influenced by factors other than pH per se. The type of oil or vinegar chosen in the preparation of home-made mayonnaise influenced the rate of autosterilization of the product. A total of seven vinegars and eight commercial oil types were compared with an acetic acid/sunflower oil control in the study of the fate of Salmonella enteritidis in home-made mayonnaise. With the vinegars, it was noted that the pH of the mayonnaise was not the sole determinant of the rate of death of salmonellas. With storage at 20 °C there was a general association between death rate and the acetic acid content of a mayonnaise. The rate of death of the salmonellas differed with the various oils: olive oil with garlic or basil showed the fastest rate of death, followed by soya, grapeseed, rapeseed, groundnut, sunflower, hazelnut and a blended olive oil.     

Influence of food acidulants on bioaccessibility of zinc and iron from selected food grains

Four common acidulants in Indian dietary, i. e., citric acid, tamarind (Tamarindus indica), amchur (Mangifera indica), and kokum (Garcinia indica) were examined for a possible influence on the bioaccessibility of zinc from selected food grains. Among the four acidulants examined, amchur and citric acid generally enhanced the bioaccessibility of zinc and iron from all the food grains studied. The increase in zinc bioaccessibility produced by citric acid was around 40% in rice and chickpea, while amchur produced around 60% increase from decorticated green gram. This positive influence of acidulants on zinc bioaccessibility from food grains was seen both in the raw and cooked form. Tamarind and kokum, the other two acidulants tested, generally did not have a favourable influence on zinc and iron bioaccessibility. This lack of positive influence of these two acidulants on mineral availability could be attributable to the presence of significant amounts of tannin in them. Citric acid and amchur also generally enhanced the bioaccessibility of iron from these food grains.     

β-Lactoglobulin Gelation and Modification: Effect of Selected Acidulants and Heating Conditions

ABSTRACT: The effect of acidulant selection, heating temperature, and heating rate on the properties of low-pH β-lactoglobulin (β-Lg) gels and powders derived from these gels was investigated by rheological and microscopic techniques. As isothermal gelation temperature was increased from 75 to 85 °C, gels made with hydrochloric and lactic acid showed more rapid gel formation and increased stress at gel fracture. Thickening and water-holding properties of powders derived from these gels also increased with temperature. Increases in gel strength and derivatized powder functionality appeared to plateau above 85 °C. Gels and derivatized powders prepared with phosphoric acid exhibited attributes similar to samples prepared with HCl and lactic acid at lower temperatures. The ion-specific ability of phosphate to increase denaturation temperature was responsible for the shift in properties of gels made with phosphoric acid. Microscopy revealed temperature effects on network building block size, but variations in rheological properties could not be linked to changes in gel micrographs. Alteration of heating rates from 2.0 to 0.2 °C/min during gelation affected the observed gelation temperature, but had little effect on final gel mechanical properties. Acid selection and gelation temperature offer alternatives to control β-Lg gel strength and the functional properties of instant thickening protein ingredients.     

Comparison of sodium acid sulfate to citric acid to inhibit browning of fresh-cut potatoes

Abstract: Sodium acid sulfate (SAS) dip treatments were evaluated against a distilled water control and citric acid (CA) to compare its effectiveness in reducing enzymatic browning of raw, French‐fry cut potatoes. Two separate studies were conducted with dip concentrations ranging from 0%, 1%, and 3% in experiment 1 to 0%, 2%, and 2.5% in experiment 2 to determine optimal dip concentrations. Russet Burbank potatoes were peeled, sliced, and dipped for 1 min and stored at 3 °C. Color, texture, fry surface pH, and microbiological analyses were conducted on days 0, 7, and 14. The 3% SAS‐ and CA‐treated samples had significantly (p < 0.0001) lower pH levels on fry surfaces than all other treatments. Both acidulants had significantly (p ≤ 0.05) lower aerobic plate counts compared to controls in both studies by day 7. However, SAS appeared to be the most effective at the 3% level in maintaining a light fry color up to day 14 and had the highest L‐values than all other treatments. The 3% SAS‐treated fry slices appeared to have the least change in textural properties over storage time, having a significantly (p = 0.0002) higher force value (kg force [kgf]) than the other treatments during experiment 1, without any signs of case‐hardening that appeared in the control and CA‐treated samples. SAS was just as comparable to CA in reducing surface fry pH and also lowering microbial counts over storage time. According to the results, SAS may be another viable acidulant to be utilized in the fresh‐cut fruit and vegetable industry.