Optimization of antifungal edible pregelatinized potato starch-based coating formulations by response surface methodology to extend postharvest life of ‘Orri’ mandarins

Abstract

Antifungal composite edible coatings (ECs) formulated with pregelatinized potato starch (PPS, 1.0-2.0 % w/w) as biopolymer, glyceryl monostearate (GMS, 0.5-1.5 %, w/w) as hydrophobe, glycerol (Gly, 0.5-1.5 %, w/w) as plasticizer, and sodium benzoate (SB, 2 % w/w) as antifungal agent were optimized using the Box-Behnken response surface methodology to extend the postharvest life of "Orri" mandarins. The second order polynomial models satisfactorily fitted the experimental data, with high values of the coefficient of determination for the different variables (R2>0.91). The individual linear effect of GMS concentration was significant in all the responses evaluated, whereas PPS only affected emulsion viscosity, fruit tacking, and weight loss of coated mandarins. Gly only affected acetaldehyde content in the juice of coated mandarins when interacted with PPS and in the quadratic effect. The optimum concentrations of PPS, GMS, and Gly for the starch-based EC based on maximum fruit quality and required emulsion properties were predicted to be 2.0, 0.5 and 1.0 % (w/w), respectively. The optimal EC reduced weight loss of mandarins and created a modified atmosphere within the fruit without negatively affecting the overall acceptability of the fruit. On the other hand, the optimized antifungal EC containing SB significantly reduced postharvest green and blue molds and sour rot on mandarins artificially inoculated with the pathogens Penicillium digitatum , Penicillium italicum and Geotrichum citri-aurantii , respectively. Therefore, the optimized antifungal EC showed potential to control the main postharvest diseases and maintain the overall quality of "Orri" mandarins and could be a suitable alternative to commercial citrus waxes formulated with conventional chemical fungicides.

Starch‐based antifungal edible coatings to control sour rot caused by Geotrichum citri‐aurantii and maintain postharvest quality of ‘Fino’ lemon

“…the hydrophilic–hydrophobic ratio of the emulsion components), but also by other factors, such as commodity and cultivar, fruit physiological stage at harvest and storage conditions 9 . In addition, several studies have confirmed that the addition of GRAS salts or food additives, as SB, to ECs greatly affects the moisture barrier properties of stand‐alone films or coatings on a variety of fresh fruits 12,14 . In this sense, using response surface methodology, our group optimized an antifungal EC formulated with 20 g L −1 SB as an antifungal ingredient and different ratios of PPS, GMS and glycerol to maintain the physicochemical and sensory quality of ‘Orri’ mandarins during storage, with F6/SB being the most effective coating to reduce weight loss, followed by F10/SB 14 .…”

“…Sodium benzoate (SB) (Sigma‐Aldrich Química S.A., Tres Cantos, Madrid, Spain) was incorporated as antifungal GRAS salt in the formulations at 20 g kg −1 . The PPS, GMS and glycerol were combined in different proportions, as detailed in Table 1, to prepare four different ECs named as F10, F6, F10/SB and F6/SB based on the optimized stable emulsions described by Soto‐Muñoz et al ., 14 where F10 and F6 were the ECs without the GRAS salt and F10/SB and F6/SB were the same ECs formulated with 20 g kg −1 SB. All formulations included sunflower lecithin and diacetyl tartaric acid esters of mono‐diglycerides (Lasenor S.A., Barcelona, Catalonia, Spain) as emulsifiers at a constant ratio of GMS:emulsifier of 2:1 (dry basis, d.b.).…”

“…9 In this regard, our group has recently developed and optimized antifungal ECs based on potato starch (PPS) and glyceryl monostearate formulated with the GRAS salt sodium benzoate as antifungal agent to maintain the physicochemical and sensory quality attributes of 'Orri' mandarins during storage at 20 °C. 14 The antifungal ability of the optimized PPS-based ECs containing sodium benzoate has been tested with good results with respect to controlling green and blue molds on different citrus species either incubated at 20 °C or stored at low temperatures. 15 However, to our knowledge, no information is available about the use of GRAS salts as ingredients of starch-based ECs for controlling sour rot caused by G. citri-aurantii on lemons and preserving fruit quality during cold storage.…”

Starch‐Based Coatings for Food Preservation: A Review

“…[ 21,24,26 ] Another disadvantage of this method is related to the possibility of the coating solution diluting other layers of the food surface and degrade its functionality. [ 31 ] This technique has been widely used, mainly for coating of fresh products as Andean blueberries, [ 25 ] eggplants, [ 32 ] cucumbers, [ 33 ] mangoes, [ 34 ] black mulberries, [ 35 ] pomegranate fruit, [ 36 ] mandarins, [ 37 ] and pumpkins, [ 38 ] and to recover and protect chestnuts [ 39 ] and almonds. [ 40 ]…”

“…In these studies was speculated that the SC containing SB could be a suitable alternative to substitute conventional chemical fungicides used to inhibit molds in fruits. [ 37,50 ] Although PSo and SB are GRAS additives, further studies must be addressed to investigate the migration of these antimicrobials into foods, as well as their effect on the rheological properties of starch solutions.…”