Sour Cherry By-products: Compositions,Functional Properties and Recovery Potentials – A Review

Abstract

Sour (tart) cherry is an industrial fruit where a considerable amount of by-products remain after processing. Sour cherry by-products consist of pomace (skin and flesh) and seeds (pit, stone) which remain after the fruit juice and IQF processes. Sour cherry pomace is characterized with a high content of phenolic compounds and the seed constitutes a high oil yield with beneficial effects on human health because of their antioxidant, antimicrobial, and anti-inflammatory properties. There has been a great interest in sour cherry by-products due to the increasing production rate of sour cherry worldwide and the increasing efforts on seeking bioactive compounds from natural sources as functional food. Thus, there have been a number of studies regarding the sour cherry pomace and sour cherry seed, especially in the last five years. The present review summarizes the chemical, biological, functional, and technological properties of the sour cherry pomace and sour cherry seed with their current and potential applications.     

Critical electric field strengths of onion tissues treated by pulsed electric fields

The impact of pulsed electric fields (PEF) on cellular integrity and texture of Ranchero and Sabroso onions (Allium cepa L.) was investigated. Electrical properties, ion leakage rate, texture, and amount of enzymatically formed pyruvate were measured before and after PEF treatment for a range of applied field strengths and number of pulses. Critical electric field strengths or thresholds (E(c)) necessary to initiate membrane rupture were different because dissimilar properties were measured. Measurement of electrical characteristics was the most sensitive method and was used to detect the early stage of plasma membrane breakdown, while pyruvate formation by the enzyme alliinase was used to identify tonoplast membrane breakdown. Our results for 100-μs pulses indicate that breakdown of the plasma membrane occurs above E(c)= 67 V/cm for 10 pulses, but breakdown of the tonoplast membrane is above either E(c)= 200 V/cm for 10 pulses or 133 V/cm for 100 pulses. This disparity in field strength suggests there may be 2 critical electrical field strengths: a lower field strength for plasma membrane breakdown and a higher field strength for tonoplast membrane breakdown. Both critical electric field strengths depended on the number of pulses applied. Application of a single pulse at an electric field up to 333 V/cm had no observable effect on any measured properties, while significant differences were observed for n≥10. The minimum electric field strength required to cause a measurable property change decreased with the number of pulses. The results also suggest that PEF treatment may be more efficient if a higher electric field strength is applied for a fewer pulses.     

Microbiological and physicochemical properties of farm bulk tank milk and antimicrobial resistance of its dominant bacteria

This study determined the antibiotic resistance of the dominant bacteria in the 85 farm BTMs according to the guidelines recommended by the epidemiological cutoff values in the EUCAST. In addition, some physicochemical and microbiological properties of farm BTMs were investigated. The milk samples were divided into two groups according to their SCC values. The milk samples with higher SCC than 400,000 cells mL⁻¹ were further examined bacteriologically, and the antibiotic resistance of isolates was determined. The average TAMB value was 6.34 log CFU/mL in farm BTM. It was found that high-SCC values did not affect other physicochemical properties of BTM samples, such as fat, protein and total solids, except for lactose content. Seventy-two strains were isolated from 45 bulk milk samples. The most prevalent bacteria were Enterococcus spp. (23.61%). The other isolates were Citrobacter spp. (12.5%), Staphylococcus spp. (12.51%), Serratia spp. (11.12%), Klebsiella spp. (9.72%), Bacillus spp. (9.72%), and Enterobacter spp. (8.33%). In antibiotic resistance analysis, 52.6% of Enterobacterales isolates showed cefoxitin resistance, and nine Enterobacterales isolates were determined as the presumptive ESBL producers. None of them was confirmed as ESBL producers. Moreover, MDR was detected in 83.3% of Enterobacter spp. isolates and all Bacillus spp. isolates. The over and inappropriate use of antibiotics in mastitis treatment may cause antibiotic-resistant microorganisms in milk. It was found that 52.7% of the isolated bacteria were MDR, which could pose a risk to public health and food safety, with the consumer's increasing interest in consuming raw milk.     

Monitoring food quality - effect of curcumin in the development of polyethylene/thermoplastic starch based smart packaging

Smart packaging relies on the one-to-one interaction of food with its packaging or its environment to monitor food quality and safety. Colorimetric pH indicators (synthetic, natural) working in a smart food packaging system are particularly striking when used with fresh foodstuffs such as fish and meat that perish quickly and require real-time freshness monitoring. In this study, curcumin (Cur) was used as a natural pH indicator to produce sustainable smart packaging material. Towards this objective, low-density polyethylene (LDPE) and thermoplastic starch (TPS) blend-based films containing Cur were prepared using a twin screw extrusion and hot-pressing processes. Besides, two different compositions of LDPE/TPS mixture (50/50 and 70/30) were used as the matrix. Thermal, mechanical, morphological properties, an affinity for water, and color change properties of LDPE/TPS/Cur films were investigated. They showed a significant color change from yellow to brown at pH: 10 at the end of the seventh day, especially in the 50 LDPE/50 TPS mixture. 50 LDPE/50 TPS mixture with 7% curcumin content gave the highest tensile strength of 8.03 Mpa. When the same mixture was used to monitor chicken meat spoilage at 25°C, meat samples have shown color changes from light yellow to light brown due to the increased content of total volatile basic amines. As a result, it has been suggested that 50 LDPE/50 TPS mixture containing 7% Cur can be used as a smart packaging material.