Food Science Commons^™

Gamma And X-Ray Irradiation Improve Postharvest Shelf-Life In 'Bartlett' Pears, Matthew Garcia

Food Science (MS) Theses

The objective of this study was to investigate the effects of gamma and x-ray treatment on ‘Bartlett’ pear physiology during postharvest storage. Freshly harvested ‘Bartlett’ pears were irradiated with gamma irradiation at 0.412 and 0.819 kGy and x-ray irradiation at 1.03 and 1.94 kGy, then stored at 0-1 ⁰C and 95% relative humidity. The pears were removed from cold storage at 45 and 75 days and allowed to ripen at room temperature for four and two days, respectively. Respiration rate and ethylene production were measured during fruit ripening. Color, firmness, titratable acidity, soluble solids contents, and occurrence of superficial scald …

Simulated Annealing-Based Hyperspectral Data Optimization For Fish Species Classification: Can The Number Of Measured Wavelengths Be Reduced?, John Chauvin, Ray Duran, Kouhyar Tavakolian, Alireza Akhbardeh, Nicholas Mackinnon, Jianwei Qin, Diane E. Chan, Chansong Hwang, Insuck Baek, Moon S. Kim, Rachel B. Isaacs, Ayse Gamze Yilmaz, Jiahleen Roungchun, Rosalee S. Hellberg, Fartash Vasefi

Food Science Faculty Articles and Research

Relative to standard red/green/blue (RGB) imaging systems, hyperspectral imaging systems offer superior capabilities but tend to be expensive and complex, requiring either a mechanically complex push-broom line scanning method, a tunable filter, or a large set of light emitting diodes (LEDs) to collect images in multiple wavelengths. This paper proposes a new methodology to support the design of a hypothesized system that uses three imaging modes—fluorescence, visible/near-infrared (VNIR) reflectance, and shortwave infrared (SWIR) reflectance—to capture narrow-band spectral data at only three to seven narrow wavelengths. Simulated annealing is applied to identify the optimal wavelengths for sparse spectral measurement with a …

Application Of A Dna Mini-Barcoding System Based On The Mitochondrial Control Region For The Identification Of Raw And Processed Tuna Products, Jiahleen Roungchun

Food Science (MS) Theses

Accurate species identification methods are needed to combat tuna fraud, improve tuna stock regulation, and mitigate health risks associated with mislabeled tuna products. The objective of this study was to conduct a market survey of raw and processed tuna products using a DNA mini-barcoding system based on the mitochondrial control region (CR). A total of 80 samples of raw, dried, and canned tuna products were collected at the retail level for CR mini-barcoding analysis. The samples underwent DNA extraction, polymerase chain reaction (PCR), and DNA sequencing of the 236-bp CR mini-barcode. The resulting sequences were searched against GenBank using the …

Assessing The Efficacy Of Bacteriological Analytical Manual (Bam) Enrichment Broths For Detection Of Salmonella Spp. In Meat Analogs, Georgia Sampson

Food Science (MS) Theses

Plant-based meat alternatives are gaining popularity as the number of market options increases. However, the recent appearance of these products on the market post-dates the validation of the current approach for isolating Salmonella from meat analogs. Therefore, the objective of this study was to compare the efficacy of the currently used Bacteriological Analytical Manual (BAM) pre-enrichment broth (lactose broth) with two additional broths (universal pre-enrichment broth and buffered peptone water) for the detection of Salmonella in five plant-based burger products. Each burger product was spiked with a Salmonella serotype (S. Enteritidis or S. Agona) that has previously been linked …

The Impact Of Processing On The Content And Composition Of Bovine Milk Extracellular Vesicles, Anna Colella

Food Science (MS) Theses

Bovine milk (BM)-based formula is an alternative for many newborns who do not consume human milk. BM contains extracellular vesicles (EVs), bioactive compounds involved in intercellular communication which regulate critical developmental processes in early life. It was hypothesized that the industrial processing of raw BM affected the content and composition of BM EVs. It is critical to understand how industrial processing affects EVs in BM since changes in the content and composition may attenuate the functions of these bioactive compounds in human health. EVs from raw BM were isolated and characterized in accordance with the Minimal Information for Studies of …

Irradiation Reduces Superficial Scald By Downregulating Ethylene And Α-Farnesene Biosynthetic Enzymes In ‘Granny Smith’ Apples, Anderson Adriano Martins Melo, Anderson Adriano Martins Melo, Paul Nifemi Olabode, Hagop Atamian, Brian Nyakundi, Criselda Toto Pacioles, Anuradha Prakash

Food Science Faculty Articles and Research

Superficial scald is a postharvest disorder of apples related to increased ethylene production in stored fruit which leads to α-farnesene accumulation and oxidation. Ionizing irradiation inhibits ethylene production and has been shown to reduce superficial scald, but this phenomenon has not been explored at the molecular level. The goal of this study was to determine the effect of irradiation on gene expression of enzymes related to ethylene and α-farnesene in ‘Granny Smith’ apples. Irradiation at 310 Gy controlled scald severity and incidence and inhibited the rise in AFS1 expression up to 90 d of cold storage followed by 7 d …

Color And Structural Modifications Of Alkaline Extracted Sunflower Protein Concentrates And Isolates Using L-Cysteine And Glutathione, Akira Ishii

Food Science (MS) Theses

Sunflower protein can be extracted at alkaline pH with sulfites or organic solvent de-phenolization of sunflower seed meals if greening is unwanted. This greening is promoted at alkaline pH when chlorogenic acid (CGA) oxidizes and reacts with free amine groups from amino acids, such as lysine. Thiol-containing dough conditioners: L-cysteine hydrochloride and reduced glutathione (GSH) were investigated as an alternative de-greening strategy to de-phenolization. Varying pH from 7 to 11 and concentration of 0.82 to 5.6 mM were randomly assigned by Response Surface Methodology (RSM) to evaluate the combined and additive greening inhibition effect of thiol and extraction pH. The …

An Investigation Into Country Of Origin Labeling, Species Authentication And Short Weighting Of Commercially Sold Frozen Fish Fillets, April M. Peterson, Gabrielle E. Mcbride, Seeret K. Jhita, Rosalee S. Hellberg

Food Science Faculty Articles and Research

Proper labeling of seafood is important to prevent economic deception and protect public health. The goal of this research was to investigate prepackaged frozen fish for Country of Origin Labeling (COOL) compliance, species labeling, net weights/short weighting, and percent glaze. A total of 111 frozen prepackaged fish fillets were purchased from grocery stores in Southern California (USA). Samples were designated as COOL compliant if they displayed both procurement method and country of origin in accordance with COOL requirements. Species labeling was examined by comparing the species identified with DNA barcoding to the acceptable market names provided in the FDA Seafood …

Bovine Liver Supplement Labeling Practices And Compliance With U.S. Regulations, Anthony J. Silva, Olive J. Dahm, Rosalee S. Hellberg

Food Science Faculty Articles and Research

Bovine liver supplements are sought after by consumers due to their nutrient-dense profile and high protein content. However, there is a lack of information regarding bovine liver supplement labeling practices. The objective of this study was to assess labeling practices and compliance with U.S. regulatory standards among commercially sold bovine liver supplements. The product labels for 49 bovine liver supplements were examined for required information, including a statement of identity; net quantity of contents; “Supplement Facts” label; ingredient statement; and name and place of business of manufacturer, packer, or distributor with domestic address or telephone number. Any claims made on …

Elucidating The Relation Between Human Milk Fatty Acids, Extracellular Vesicles, And Infant Developmental Outcomes In The First Year Of Life, Diana Bickmore

Food Science (MS) Theses

For most infants, human milk is the recommended source of nutrition. Improved developmental outcomes have been reported in infants that consume human milk compared to infant formula. Essential fatty acids (EFAs) confer health benefits. However, EFAs cannot be synthesized by the body, and therefore must be consumed in diet. Extracellular vesicles (EVs) are nanoparticles containing a lipid bilayer membrane and are present in human milk. Methods of EV isolation such as ultracentrifugation (UC) may not be feasible for the study of EVs in human milk due to the need for large sample volume, which may not be available. The objectives …

Impact Of Gamma Irradiation On Post-Harvest Disorders In 'Bartlett' Pears, Michelle Tu

Food Science (MS) Theses

The goal of this research was to determine the effect of irradiation on post-harvest disorders and ripening quality of ‘Bartlett’ pears stored for 3 months in air. ‘Bartlett’ pears were treated at 470 and 940 Gy and held at -1 - 0 ˚C at 95 % humidity. At 0, 45, and 90 days following treatment, the pears were brought to room temperature and allowed to ripen. The pears were then monitored for changes in respiration rate and ethylene production. After reaching the climacteric peak, pears were evaluated for incidence of post-harvest disorders, ACS and ACO enzyme activities, and quality factors …

Authentication Of Red Snapper (Lutjanus Campechanus) Fillets Using A Combination Of Real-Time Pcr And Dna Barcoding, Rachel B. Isaacs, Rosalee S. Hellberg

Food Science Faculty Articles and Research

Red snapper (Lutjanus campechanus) is a historically overfished and highly valued species that is commonly substituted with other fish, such as tilapia, rockfish, and other snapper species. The objective of this study was to assess the ability of real-time PCR to be used as a screening tool to rapidly test commercial fillets for the presence of red snapper, followed by species identification of negative samples with DNA barcoding. A total of 24 frozen, fresh, or thawed (previously frozen) fillets labeled as “red snapper” were tested with real-time PCR, along with 54 fillets from fish that are common substitutes …

Effect Of Dried Mushroom Powder On Thiol Content In Lyophilized And Native Bovine Myofibrillar Protein, Allany Chayasing

Food Science (MS) Theses

Thiol oxidation can form disulfide bonds that modify protein conformations, resulting in lower free thiol content. The effect of dried (lyophilized and oven-dried) mushroom powder (Agaricus bisporus or Pleurotus ostreatus) added to bovine lyophilized and native myofibrillar proteins (MP) on thiol oxidation was investigated. Mixtures of 10mg/mL MP with 0.1% and 0.2% mushroom powder in 0.3M NaCl were stored at 2ºC and 80 ºC for 10 days. Oven-dried A. bisporus had higher Folin-Ciocalteu reducing capacity at 8.05±0.71 gallic acid equivalent (GAE) mg/g compared to 4.97±0.20 GAE mg/g oven-dried P. ostreatus. Lyophilized P. ostreatus contained 164% more ergothioneine than …

Effect Of Low Dose Irradiation On Expression Of Genes Involved In Ethylene Biosynthesis Of 'Granny Smith' Apples, Brian Nyakundi

Food Science (MS) Theses

Superficial scald is a physiological disorder characterized by skin browning that appears during or after storage of ‘Granny Smith’ apples. The mechanism for scald development is not fully understood, but it is hypothesized that scald formation is related to increased ethylene production. In apples, low dose irradiation induced ethylene reduction appears to be directly related to prevention of superficial scald. However, the molecular basis of such an irradiation induced effect is not known. In this study, effort was made to better understand the molecular basis of the decrease in ethylene production in apple fruit after treatment with x-ray irradiation. ‘Granny …

Authentication Of Species In Bison Products Using Molecular Methods, Zerika Scales

Food Science (MS) Theses

American bison (Bison bison) meat is vulnerable to species substitution due to its high value and similar appearance to less expensive meats, such as beef from domestic cattle (Bos taurus). DNA barcoding of the cytochrome c oxidase subunit 1 (CO1) gene is a commonly used method to test for meat species mislabeling. However, due to historical hybridization between the American bison and domestic cattle, additional testing is required to confirm species. The objective of this study was to perform a market survey of products sold as bison meat and verify the species of each product using …

Labeling Compliance, Species Authentication And Net Weight Identification Of Frozen Fish Fillets Sold In Grocery Stores In Southern California, April Peterson

Food Science (MS) Theses

Proper labeling of seafood is important to prevent economic deception, promote consumer awareness, and prevent exposure of at-risk groups to certain allergens and toxins. The objective of this study was to investigate prepackaged frozen fish sold in Southern California for Country of Origin Labeling (COOL) compliance, species authentication, use of acceptable market names, net weights, and percent glaze. A total of 111 frozen fish fillets from 13 different fish categories were purchased from grocery stores in Southern California. The fish categories targeted for this study were: catfish, cod, flounder, halibut, mahi-mahi orange rough, pollock, salmon, swai, swordfish, tilapia, tuna, and …

Inspecting Species And Freshness Of Fish Fillets Using Multimode Hyperspectral Imaging Techniques, Jianwei Qin, Fartash Vasefi, Rosalee S. Hellberg, Alireza Akhbardeh, Rachel B. Isaacs, Ayse Gamze Yilmaz, Chansong Hwang, Insuck Baek, Walter F. Schmidt, Moon S. Kim

Food Science Faculty Articles and Research

This study developed multimode hyperspectral imaging techniques to detect substitution and mislabeling of fish fillets. Line-scan hyperspectral images were collected from fish fillets in four modes, including reflectance in visible and nearinfrared (VNIR) region, fluorescence by 365 nm UV excitation, reflectance in short-wave infrared (SWIR) region, and Raman by 785 nm laser excitation. Fish fillets of six species (i.e., red snapper, vermilion snapper, Malabar snapper, summer flounder, white bass, and tilapia) were used for species differentiation and frozen-thawed red snapper fillets were used for freshness evaluation. A total of 24 machine learning classifiers were used for fish species and freshness …

De Novo Sequencing And Analysis Of Salvia Hispanica Tissue-Specific Transcriptome And Identification Of Genes Involved In Terpenoid Biosynthesis, James Wimberley, Joseph Cahill, Hagop S. Atamian

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Salvia hispanica (commonly known as chia) is gaining popularity worldwide as a healthy food supplement due to its low saturated fatty acid and high polyunsaturated fatty acid content, in addition to being rich in protein, fiber, and antioxidants. Chia leaves contain plethora of secondary metabolites with medicinal properties. In this study, we sequenced chia leaf and root transcriptomes using the Illumina platform. The short reads were assembled into contigs using the Trinity software and annotated against the Uniprot database. The reads were de novo assembled into 103,367 contigs, which represented 92.8% transcriptome completeness and a diverse set of Gene Ontology …

Detection Of Fish Fillet Substitution And Mislabeling Using Multimode Hyperspectral Imaging Techniques, Jianwei Qin, Fartash Vasefi, Rosalee S. Hellberg, Alireza Akhbardeh, Rachel B. Isaacs, Ayse Gamze Yilmaz, Chansong Hwang, Insuck Baek, Walter F. Schmidt, Moon S. Kim

Food Science Faculty Articles and Research

Substitution of high-priced fish species with inexpensive alternatives and mislabeling frozen-thawed fish fillets as fresh are two important fraudulent practices of concern in the seafood industry. This study aimed to develop multimode hyperspectral imaging techniques to detect substitution and mislabeling of fish fillets. Line-scan hyperspectral images were acquired from fish fillets in four modes, including reflectance in visible and near-infrared (VNIR) region, fluorescence by 365 nm UV excitation, reflectance in short-wave infrared (SWIR) region, and Raman by 785 nm laser excitation. Fish fillets of six species (i.e., red snapper, vermilion snapper, Malabar snapper, summer flounder, white bass, and tilapia) were …

Microplate Immunocapture Coupled With The 3m Molecular Detection System And Selective Plating For The Rapid Detection Of Salmonella Infantis In Dry Dog Food And Treats, Danielle K. Rosen, Miguel Gallardo, Mcclain Vail, Rosalee S. Hellberg

Food Science Faculty Articles and Research

The objective of this study was to use microplate immunocapture (IC) to reduce the enrichment time required for detection of Salmonella in pet food with the 3 M Molecular Detection System (MDS) or selective plating on XLD. Dog food and pig ear treats were inoculated with Salmonella Infantis at concentrations of 10⁰–10⁴ CFU/25 g, followed by a 3-h enrichment, then microplate IC and 3 M MDS or microplate IC and selective plating on XLD. Another set of samples underwent a traditional 24-h enrichment followed by 3 M MDS or selective plating. Based on the results of three …

Pcr Cloning Combined With Dna Barcoding Enables Partial Identification Of Fish Species In A Mixed-Species Product, Anthony J. Silva, Michael D. Kawalek, Donna M. Williams-Hill, Rosalee S. Hellberg

Food Science Faculty Articles and Research

DNA barcoding is a valuable tool for regulatory identification of fish species; however, it does not perform well when multiple species are present within the same food product. Therefore, the objective of this study was to examine the use of PCR cloning to identify fish in a mixed-species product that cannot be identified with standard DNA barcoding. A total of 15 fish ball mixtures were prepared with known amounts of Nile tilapia (Oreochromis niloticus), Pacific cod (Gadus macrocephalus), and walleye pollock (Gadus chalcogrammus). Three subsamples from each fish ball underwent DNA extraction, full DNA barcoding (655 bp), and mini-barcoding (226 …

Formation Of Maillard Reaction Products And Chlorogenic Acid-Quinone Induced Green Pigments In Gluten-Free Pretzels Made Using Sunflower Flour, Rashi Bhatnagar

Food Science (MS) Theses

The two color-developing reactions that occur when soft pretzels are baked using sunflower flour (SFF) in aqueous alkali environment are chlorogenic acid (CGA)-quinone induced greening and Maillard browning. This study aimed to determine how CGA content in two different SFFs containing 45% and 55% protein (Heliaflor^® 45 and 55, respectively) affected the formation of green trihydroxybenzacridine (TBA) and Maillard reaction products (MRPs) in soft baked pretzels. Pretzels were baked with five doughs prepared using a pre-blended gluten-free flour, consisting of sweet white rice flour, whole grain brown rice flour, potato starch, whole grain sweet white sorghum flour, tapioca flour, …

Oyster Mushroom (Pleurotus Ostreatus) Stipe Peptides As In-Vitro Radical Scavenging, Ferrous Iron Chelating, & Ferric Reducing Antioxidant Compounds, Suraj Meharwade

Food Science (MS) Theses

Ferrous iron chelating, ABTS radical scavenging, and ferric reducing antioxidant activity of mushroom stipe peptides obtained using Protamex® and V8 protease has not been investigated. Additionally, the effects of peptides on protein carbonyl formation during myofibrillar oxidation is unknown. Oxidation of lysine, arginine, and proline in myofibrillar protein from red meat results in reduced meat quality owing to changes in water composition. Therefore, the objective of this study was to compare the antioxidant performance of <1 kDa and 1-3 kDa mushroom peptides obtained by Protamex®-V8 hydrolysis against mushroom hydrolysate, mushroom protein, and mushroom stipe for radical scavenging, ferrous chelating, and ferric reducing activity, as well as their effects on protein carbonyl formation within a protein oxidation system. <1 kDa peptides exhibited significantly higher (p < 0.05) in-vitro ferrous iron chelating activity and ABTS radical scavenging activity as compared to mushroom stipe and 1-3 kDa peptides. Whereas, 1-3 kDa peptides demonstrated significantly …

Labeling Compliance And Species Authentication Of Fish Fillets Sold At Grocery Stores In Southern California, Priscila Liou, Angela Banda, Rachel B. Isaacs, Rosalee S. Hellberg

Food Science Faculty Articles and Research

Seafood mislabeling has numerous consequences, including economic deception and food safety risks. The focus of this study was to investigate fish species labeling, use of acceptable market names, and Country of Origin Labeling (COOL) compliance for fresh fish fillets sold at grocery store seafood counters in Southern California. A total of 120 fillets representing 16 different categories of fish were collected from 30 Perishable Agricultural Commodities Act (PACA)-listed grocery stores. Each sample underwent DNA barcoding to identify the species. Acceptable market names were confirmed using the FDA Seafood List. Samples were determined to be compliant with COOL if both …

Antiproliferative And Apoptotic Effects Of Proteins From Black Seeds (Nigella Sativa) On Human Breast Mcf-7 Cancer Cell Line, Yamna Khursid, Basir Syed, Shabana U. Simjee, Obaid Beg, Aftab Ahmed

Pharmacy Faculty Articles and Research

Background

Nigella sativa (NS), a member of family Ranunculaceae is commonly known as black seed or kalonji. It has been well studied for its therapeutic role in various diseases, particularly cancer. Literature is full of bioactive compounds from NS seed. However, fewer studies have been reported on the pharmacological activity of proteins. The current study was designed to evaluate the anticancer property of NS seed proteins on the MCF-7 cell line.

Methods

NS seed extract was prepared in phosphate-buffered saline (PBS), and proteins were precipitated using 80% ammonium sulfate. The crude seed proteins were partially purified using gel filtration …

Effects Of Poor Sanitation Procedures On Cross-Contamination Of Animal Species In Ground Meat Products, Sunjung Chung, Rosalee S. Hellberg

Food Science Faculty Articles and Research

The presence of <1% of an undeclared species in ground meat is generally thought to be indicative of cross-contamination as opposed to intentional mislabeling; however, this has not been experimentally tested. The objective of this study was to quantify the effects of poor sanitation on the cross-contamination of animal species in ground meat products, with the example of undeclared pork in ground beef. Cross-contamination was quantified using real-time polymerase chain reaction (PCR). Three different sanitation treatments were tested with a commercial grinder (“no cleaning”, “partial cleaning”, or “complete cleaning”) in between grinding of pork and beef samples (13.6 kg each). A 100-g sample was collected for each 0.91 kg (2 lb) of beef processed with the grinder and each sanitation treatment was tested twice. For the “no cleaning” treatment, the first 100-g sample of ground beef run through the grinder contained 24.42 ± 10.41% pork, while subsequent samples (n = 14) contained <0.2% pork. With “partial cleaning,” the first sample of ground beef contained 4.60 ± 0.3% pork and subsequent samples contained <0.2% pork. Pork was not detected in ground beef following “complete cleaning.” These results indicate that incomplete cleaning of grinding equipment leads to species cross-contamination at levels of <1% in most cases. Proper sanitation procedures must be followed when grinding multiple species in order to prevent cross-contamination and product mislabeling.

Development Of A Dna Mini-Barcoding Protocol Targeting Coi For The Identification Of Elasmobranch Species In Shark Cartilage Pills, Rowena J. Zahn, Anthony J. Silva, Rosalee S. Hellberg

Food Science Faculty Articles and Research

Many elasmobranch (shark and ray) species are considered threatened and their identification in processed products is important for conservation and authentication purposes. However, identification of elasmobranch species in shark cartilage pills has proven difficult using existing methodologies. The objective of this study was to develop a DNA mini-barcoding protocol using a ~130 bp region of the cytochrome c oxidase subunit I (COI) gene for species identification in shark cartilage pills. A total of 22 shark cartilage products underwent DNA extraction in duplicate using the DNeasy Blood and Tissue Kit (Qiagen). The effectiveness of a clean-up step following DNA extraction was …

Multi-Instrument Evaluation Of A Real-Time Pcr Assay For Identification Of Atlantic Salmon: A Case Study On The Use Of A Pre-Packaged Kit For Rapid Seafood Species Identification, Amanda A. Naaum, Rosalee S. Hellberg, Tara A. Okuma, Robert H. Hanner

Food Science Faculty Articles and Research

Protecting the seafood supply chain from species substitution is critical for economic, health, and conservation reasons. DNA-based methods represent an effective means to detect species substitution, but current methods can be time consuming or costly, and require specialized instruments and operators. Real-time PCR provides an alternative that can be performed quickly, and in some cases even on-site. The use of commercial kits reduces the expertise required by the operator and therefore increases accessibility to testing. This potentially increases the likelihood of adoption into the supply chain, but only if the kits are robust across multiple operators, instruments, and samples. In …

Real-Time Pcr Combined With Dna Barcoding For The Authentication Of Red Snapper (Lutjanus Campechanus) Fillets, Rachel Isaacs

Food Science (MS) Theses

Seafood substitution is a worldwide problem due to factors such as limited monitoring coupled with complex supply chains. Red snapper (Lutjanus campechanus) is a highly valued and overfished species that is commonly substituted with other fish, such as tilapia, rockfish, and other snapper species. DNA barcoding is typically used by regulatory agencies to detect seafood substitution; however, it is expensive and time-consuming. A rapid, real-time PCR assay targeting red snapper was developed previously for use in fisheries management; however, it has not been tested for its ability to detect red snapper species substitution. The objective of this study …

Physiological Response Of ‘Fuji’ Apples To Irradiation And The Effect On Quality, Nasim Kheshti, Anderson Adriano Martins Melo, Alan Baquero Cedeno, David Obenland, Anuradha Prakash

Food Science Faculty Articles and Research

The objective of this study was to determine the influence of irradiation-induced physiological responses on quality parameters in ‘Fuji’ apples. Apples were treated at 377 and 1148 Gy, stored for 7 days at 1 °C to mimic ground transportation to Mexico and another 7 days at ambient temperature to simulate retail and consumer storage conditions. Irradiation suppressed ethylene production, especially in the 1148 Gy treated apples, which was consistent with lower activities of 1-aminocyclopropane-1-carboxylate oxidase (ACO). A dose-dependent increase in respiration rate corresponded with decreases in titratable acidity (TA) and organic acids. Higher electrolyte leakage in apples irradiated at the …