No abstract

The effectiveness of edible coatings containing sour whey powder (SWP), compared with soy protein isolate (SPI) and calcium caseinate (CC), in reducing oxidative browning and moisture loss during storage (4C) of cut apples, potatoes, carrots, and onions was investigated. Oxidative discoloration, as determined by the Commission Internationale de I'Eclairage L*a*b* color scale, was significantly reduced (P < 0.05) by treatments over a storage time of 120 min. Loss of lightness was reduced by CC, SPI and SWP coatings. These respectively showed 2.7, 3.3 and 1.5% change of L* value in coated apples as compared with 7.4% in the control. Browning in cut potatoes was significantly reduced from a 145.1% increase in the a* value of the control to 45.9, 37.0 and 30.3% increase for CC, SPI and SWP treatments, respectively. The b* values also reflected the effectiveness of SWP. The moisture barrier effect, tested over a period of 5 days at 4C, was significantly better for the treatments than control. SWP was the best and significantly reduced moisture loss in potatoes and carrots by 40 and 59%, respectively, over control. Cut onions did not show any treatment effect both in terms of off-color development and moisture loss. The reasons for the excellent moisture barrier and antioxidative property of SWP were discussed. PRACTICAL APPLICATIONSOxidative degradation of fresh fruits and vegetables is a major problem faced by the industry today.

Soy protein isolate (SPI)‐based edible coating was used to reduce oxidative degradation of Han‐Woo (Korean cow) beef stored at 4C for 5 days in aerobic packaging. The SPI coating reduced (P < 0.05) thiobarbituric acid‐reactive substances and peroxide value (PV) formation compared with control beefs. At 5 days of storage, the percent inhibition of TBARS and PV for SPI‐coated beefs compared with the control was 28.5 and 32.2%, respectively. SPI coating prevented loss of Hunter L and a values of beef compared with the control after 2 days of storage. The ability of the SPI coating to provide a moisture barrier for the beefs was reduced (P < 0.05). In addition, a reduction of moisture loss by 31.4% compared with the control was achieved by SPI coating after 5 days of storage. However, SPI coating of beefs did not inhibit the growth of either total plate counts or Listeria monocytogenes during storage. Overall, SPI coating can effectively be used as a natural antioxidative coating to extend the shelf life of beef by reducing oxidation and moisture loss during refrigerated storage in aerobic packaging. PRACTICAL APPLICATIONS Oxidative and microbiological degradation are major problems faced by the food industry today. As the educated consumer is highly health conscious, any effort in extending the shelf life will have to be nonchemical, and preferably natural. Our research investigated the possibility of using soy protein as a final coating material to enhance the freshness of beef packed aerobically during refrigerated storage. Soy protein‐based edible coating used in this present study was capable of acting as a natural antioxidative and moisture barrier coating for meat products to maintain the quality and the shelf‐life during refrigerated storage.

Whey protein-based edible coating was used to reduce oxidative degradation and microbial growth of low-fat sausages (LFSs) stored at 4 degrees C for 8 wk, under aerobic package. Whey protein coating reduced (P<0.05) thiobarbituric acid-reactive substances (TBARS) and peroxide value (PV) formation compared to control sausages. The percent inhibition of TBARS and PV for whey protein-coated sausages, compared to the control, was 31.3% and 27.1%, respectively. The ability of the whey protein coating to provide a moisture barrier for the sausages was reduced (P<0.05). In addition, a reduction of moisture loss by 36.7% compared to the control was achieved by whey coating. However, whey protein coating of LFSs did not inhibit the growth of either the total number of aerobic bacteria or of Listeria monocytogenes. These results indicated that whey protein coating had an antioxidative activity in LFSs under aerobic package during refrigerated storage.

Antioxidative properties of sour (cottage) were evaluated with (thermized) and without (native) heat treatment (80°C for 30 min). A model system comprising a Tween 20 stabilized peanut oil in phosphate buffer (pH 7.0) emulsion containing lipid oxidation catalysts, FeCl 3, H2O2 and ascorbate was used. Native sour whey powder (SWP) was significantly better than thermized whey in terms of limiting the formation of thiobarbituric acid‐reactive substances and peroxide value. Antioxidative ability was best at pH 3.0 and decreased with increasing pH. SWP (20%, w/v) was significantly better than all commonly used antioxidants tested after 96 h of incubation at 40°C.