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.     

Microbiological quality of fresh-cut sweet potatoes

Sweet potato roots were dipped in various concentrations of chlorine for 5 min at 1 or 20 °C before and after slicing, and then stored at 2 or 8 °C for 14 days to evaluate the effects of different chlorine treatments and storage temperatures on the microbiological quality of fresh‐cut sweet potato slices. The microflora of fresh‐cut sweet potato slices was dominated by mesophiles, followed by psychrotrophs and fungi initially and during storage. The 2 °C storage was necessary to keep the microbial load at a low level. No spoilage was observed in fresh‐cut sweet potatoes at both storage temperatures for 14 days. Chlorination of sweet potatoes before slicing was not effective in ensuring acceptable microbiological quality of fresh‐cut sweet potatoes. Dipping slices in 200 ppm chlorine at 1 °C reduced the population of all micro‐organisms during storage.     

鲜切甘薯酶促褐变调控的研究

采用不同浓度的D-异抗坏血酸钠和柠檬酸分别处理鲜切甘薯,研究其在10℃贮藏过程中的酶促褐变反应,揭示不同褐变抑制剂对鲜切甘薯酶促褐变的调控机制。结果表明,0.5%～1.5%D-异抗坏血酸钠和低浓度(0.01%～0.03%)柠檬酸均延缓了鲜切甘薯酶促褐变的发生,有效抑制了PPO和POD的活性,降低了总酚含量;但高浓度(≥0.05%)柠檬酸处理反而加速了酶促褐变反应的进行。比较两种褐变抑制剂,D-异抗坏血酸钠抑制效果更好,其最佳浓度为1.0%。     

延长鲜切面货架期的研究

研究了酒精,脱氢乙酸,二丁基羟基甲苯,对羟基苯甲酸丙酯,山梨酸钾,过氧化苯甲酰,叔丁基对苯二酚,鹿蹄草8种防腐剂在恒温冷藏下（4℃～8℃）对鲜切面保藏期的影响,得出了有效延长鲜切面保藏期的防腐剂组合：脱氢乙酸0．06％,山梨酸钾0．06％,酒精4％（均以面粉添加量计）,可延长鲜切面保存时间24～48h。     

Effect of in‐package gaseous ozone treatment on shelf life of blanched potato strips during refrigerated storage

The effect of in‐package gaseous ozone treatment on microbiological and colour quality of blanched potato strips was investigated. Potato strips were first blanched in 0.5% CaCl₂ solution at 60 °C for 10 min, second blanched in boiling water for 5 min, then exposed to room air for 30 min and packaged. Ozone gas (5%, wt/wt) was injected into each bag. Strips were subjected to a batch ozone treatment for 20 s or a continuous ozone treatment for 5, 15 or 30 min. Microbial growth was observed on day one for bags with no ozone treatment. Continuous ozone treatment was effective in extending the shelf life of potato strips compared to batch ozone treatment, and there was no microbial growth for 30‐ and 15‐min continuous ozone‐treated strips after 28 and 21 days of refrigerated storage, respectively. No significant difference was observed between the colour of blanched strips and ozone‐treated blanched strips. These results indicate that in‐package gaseous ozone treatment can be used for maintaining quality and improving shelf life of blanched potato strips.     

Recent advances in extending the shelf life of fresh Agaricus mushrooms: a review

Postharvest browning of Agaricus mushrooms is a severe problem that reduces the shelf life of harvested mushrooms because of their continued respiration and biochemical activity. There are no simple answers and no single treatment is known to limit overall quality deterioration. However, there are several strategies that are being implemented in order to reduce the rate of respiration for mushrooms. Packaging technology is the common denominator that allows us to implement these strategies and thus is key to quality preservation. In this review, first, the major factors involved in postharvest quality deterioration are discussed and then technological advances/methods used to counteract these hurdles are presented. Copyright © 2010 Society of Chemical Industry     

Effects of aqueous ozone treatments on microbial load reduction and shelf life extension of fresh‐cut apple

Aqueous ozone was first used to take the place of chlorine as fresh‐cut apples sanitiser. Aqueous ozone (1.4 mg L^?1) treatments were evaluated for their effectiveness on microbial growth, quality attributes and shelf life of fresh‐cut apples. The results indicated that aqueous ozone treatments for 5 and 10 min achieved accepted microbial quality and, respectively, reduced total bacteria counts by 1.83 and 2.13 log₁₀CFU g^?1 compared with the control samples on the 12th day. The ethylene production, polyphenol oxidase and peroxidase activities, and total phenol and malondialdehyde contents were reduced by aqueous ozone treatments. In addition, this sanitiser also delayed the quality deterioration of fresh‐cut apples and enhanced their antioxidant capacity. Therefore, it was recommended to sanitise fresh‐cut apples with aqueous ozone (1.4 mg L^?1) for 5 min, which applied to industrial production requirement for both efficiency and costs and could extend the shelf life up to 10 days.     

Use of images in shelf life assessment of fruit salad

Fruit salads stored for different lengths of time as well as their images were used to estimate sensory shelf life by survival analysis. Shelf life estimates obtained using fruit salad images were longer than those achieved by analyzing the real product. This was attributed to the fact that images are 2-dimensional representations of real food, probably not comprehensive of all the visual information needed by the panelists to produce an acceptability/unacceptability judgment. Images were also subjected to image analysis and the analysis of the overall visual quality by a trained panel. These indices proved to be highly correlated to consumer rejection of the fruit salad and could be exploited for routine shelf life assessment of analogous products. To this regard, a failure criterion of 25% consumer rejection could be equivalent to a score 3 in a 5-point overall visual quality scale. PRACTICAL APPLICATION: Food images can be used to assess product shelf life. In the case of fruit salads, the overall visual quality assessed by a trained panel on product images and the percentage of brown pixels in digital images can be exploited to estimate shelf life corresponding to a selected consumer rejection.     

臭氧水清洗结合气调包装对鲜切杭白菜保鲜效果的研究

以1.8mg/L臭氧水清洗的鲜切杭白菜为试验材料,研究不同气体组分的气调包装(CK为空气;A为5%O_2+5%CO_2+90%N_2;B为5%O_2+10%CO_2+85%N_2;C为10%O_2+5%CO_2+85%N_2;D为10%O_2+10%CO_2+80%N_2)对鲜切杭白菜保鲜效果的影响。结果表明:B组低氧高二氧化碳的包装能有效地抑制鲜切杭白菜上微生物的生长,保持其较好的感官品质,同时延缓VC、叶绿素及可溶性固形物含量的降低,防止杭白菜过快失水,有效地保证鲜切杭白菜的货架期在15d以上。     

Effect of ozone and calcium lactate treatments on browning and texture properties of fresh‐cut lettuce

The effects of three treatments, 1 mg L^?1 ozone at 18–20 °C, 15 g L^?1 calcium lactate (CLac) at 50 °C and a combination thereof, were compared on fresh‐cut lettuce over 10 days of refrigerated storage. Respiration rate, browning and texture were examined as main quality indicators. The use of ozone produced a significantly (P < 0.05) higher oxygen decline than the use of CLac (from day 3 to day 10). At the end of storage, CLac (alone or combined with ozone) samples had higher oxygen content (～9%) than ozone samples (～6%). Enzymatic activity decreased significantly (P < 0.05) in ozone samples. Polyphenol oxidase activity in fresh‐cut lettuce treated with ozone (alone or combined with CLac) showed lower values on day 1 (<2500 units g^?1) and at the end of storage (<3000 units g^?1) than CLac samples (4000–4800 units g^?1). Ozone also reduced peroxidase activity to ～300 units g^?1 after treatment. Finally, pectin methylesterase activity was also reduced with ozone, showing a negative effect on textural properties. Data suggested that CLac maintained quality markers better than treatments with ozone and ozone/CLac combination over 10 days of storage. Copyright © 2006 Society of Chemical Industry     

茉莉酸甲酯对鲜切甘薯伤害防御反应的研究

为了研究不同浓度茉莉酸甲酯(MeJA)处理对鲜切甘薯伤害防御反应的影响,将甘薯切割成1cm×1cm×1cm的块状,在低浓度(15μmol/L)MeJA和高浓度(150μmol/L)MeJA下贮藏,每隔1d测定自由基清除系统工具酶(POD、CAT、APX、SOD)的活性、膜质过氧化程度、H2O2含量和多酚氧化酶(PPO)活性。实验结果表明,高浓度MeJA处理的鲜切甘薯可以显著提高CAT、APX、POD和PPO酶活性,抑制H2O2含量增加;SOD活性没有显著变化。高浓度MeJA处理可有效诱导防御反应发生,同时,通过提高自由基清除系统工具酶活性,使膜脂过氧化程度减轻;低浓度MeJA处理效果不显著。综合分析认为,150μmol/LMeJA是诱导鲜切甘薯防御反应产生的适宜处理浓度,作为一种新型诱变剂可以应用于鲜切果蔬的生产实践。     

臭氧在鲜切果蔬保鲜中的应用

对臭氧在鲜切果蔬保鲜中的应用进行了综述。详细介绍了臭氧保鲜的机理、臭氧保鲜的影响因素、臭氧与其他保鲜技术在鲜切果蔬保鲜中的协同作用,并分析了臭氧在鲜切果蔬保鲜应用中存在的问题及今后的发展方向。     

Surface treatments and coatings to maintain fresh‐cut mango quality in storage

BACKGROUND: Edible coatings may extend fresh‐cut fruit storage by preventing moisture loss and decreasing gas exchange. This study evaluated the effect of an antibrowning dip (calcium ascorbate, citric acid and N‐acetyl‐L ‐cysteine), followed or not with carboxymethylcellulose (CMC) or carrageenan coatings on quality of fresh‐cut mangoes stored at 5 °C for up to 20 days. A fourth treatment, only used in one of four experiments, consisted of chitosan. Treatments were applied on ‘Tommy Atkins’, ‘Kent’ and ‘Keitt’ mangoes harvested from Homestead (FL), and on imported store‐bought mangoes. RESULTS: The antibrowning dips maintained the best visual quality during storage for all cultivars, as indicated by higher b*, hue and L*. The CMC coating maintained similar visual quality, but carrageenan or chitosan decreased L* and b*. The antibrowning dip containing calcium ascorbate reduced firmness loss on cut pieces of ‘Keitt’, ‘Kent’ and store‐bought mangoes. The antibrowning treatment maintained higher titratable acidity for ‘Kent’ and ‘Keitt’, resulting in lower sensory sweetness. CONCLUSION: This study with repeated experiments showed that calcium ascorbate with citric acid and N‐acetyl‐L ‐cysteine maintained cut mango slices attractiveness in storage by keeping light color in both varieties. The addition of a polysaccharide coating did not consistently improve quality. Published in 2010 by John Wiley & Sons, Ltd.     

The use of ozone to extend the shelf‐life and maintain quality of fresh produce

Fresh produce has been recognised as a healthy food, thus there is increasing consumer demand for fresh fruit and vegetables. The shelf‐life of fresh produce, however, is relatively short and is limited by microbial contamination or visual, textural and nutritional quality loss. There are many methods to reduce/eliminate microorganisms present in food and ozone treatment is one of them. The use of ozone by the fresh produce industry is a good alternative to chemical treatments, e.g. the use of chlorine. The effectiveness of ozone as an antimicrobial agent has previously been reviewed and has been updated here, with the latest findings. The main focus of this review is on the effects of ozone on the fresh produce quality, defined by maintenance of texture, visual quality, taste and aroma, and nutritional content. Furthermore, ozone has been found to be efficient in reducing pesticide residues from the produce. The treatments that have the ability to reduce microbial contamination of the product without having an adverse effect on its visual, textural and nutritional quality can be recommended and subsequently incorporated into the supply chain. A good understanding of all the benefits and limitations related to the use of ozone is needed, and relevant information has been reviewed in this paper. © 2014 Society of Chemical Industry